Knock Sensor
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Paul Bartz
Jun 18, 2010, 10:21:16 PM6/18/10
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Anyone have words of wisdom on choosing the subject (e. g. is there any relation
to the engine displacement vs. what sensor to use)??? If not, are there any
technical differences between the various ones???
to the engine displacement vs. what sensor to use)??? If not, are there any
technical differences between the various ones???
For those who are utilizing the sensor, what part number did you use???
Paul Bartz
Kalamazoo MI
78 Royale Rear Twins
Jim Kanomata
Jun 19, 2010, 12:04:37 AM6/19/10
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Paul,
from what I have experienced, the displacement is not the factor.
Jim Kanomata
Applied/GMC, Fremont,CA
ji...@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
George Beckman
Jun 19, 2010, 1:45:28 AM6/19/10
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Paul,
Jim is correct from what we know. A sensor for a 454 fits a number of engines. I am pasting a posting before that lists the same sensor as fitting 350s.
On Jun 18, 2010, at 9:04 PM, Jim Kanomata wrote:
from what I have experienced, the displacement is not the factor.
Here is the one I got and what it fits:There are 454's listed along side 350s and 262s. Randy has read that it is the cylinder size and the that V6 has about the same bore as the 454. I don't know about the 350s.
This part also fits:
Larry Davick
Jun 19, 2010, 3:10:31 AM6/19/10
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Isn't it the placement of the sensor in the exhaust pipe that is more critical than the particular sensor?
Narrow Band sensors are mounted close to the exhaust manifold and Wide Band sensors are mounted further downstream - no?
Larry Davick
(with more questions than answers)
Bruce Hislop, Perth Communications
Jun 19, 2010, 9:08:46 AM6/19/10
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Larry,
I think you are talking about the O2 sensor.
I just asked for a sensor for a 90's something 454 engine and installed it in the coolant plug hole on the lower passenger side of the block.
I think the knock module might be more important. I took the excellent Men's Mall EFI writeup and found the PN in a pile of them at the wreckers.
My EBL rarely reports any more Knocks after the 200 to 500 from the starter at startup.
I think you are talking about the O2 sensor.
I just asked for a sensor for a 90's something 454 engine and installed it in the coolant plug hole on the lower passenger side of the block.
I think the knock module might be more important. I took the excellent Men's Mall EFI writeup and found the PN in a pile of them at the wreckers.
My EBL rarely reports any more Knocks after the 200 to 500 from the starter at startup.
Bruce Hislop
Perth Communications
br...@perthcomm.com
Sent from my Blackberry Curve
From: Larry Davick <ljda...@comcast.net>
Date: Sat, 19 Jun 2010 00:10:31 -0700
To: <gmcm...@googlegroups.com>
Subject: Re: [GMCMH-EFI] Knock Sensor
Paul Bartz
Jun 19, 2010, 3:00:55 PM6/19/10
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Jim:
From www.eng-tips.com/viewthread.cfm?qid=54276, scroll down to time stamp 28 Jul 03 15:47 (on the right side of the page). He gives a SAE Technical Paper Series 900488, Combustion Knock Sensing: Sensor Selection and Application Issues, authored by Steven M. Dues, Joseph M. Adams, and George A. Shinkle: Delco Remy Div, General Motors Corp. A chart from the SAE paper shows that the fundamental frequency of a 75mm bore is about 7kHz, a 94mm bore is about 6.0 kHz, while that of a 110mm bore is about 5.2kHz. The chart shows a fairly linear relationship of frequency to bore diameter. However, in searching on that item, SAE wants money.
He goes on to say: In the mid '90's, a GM engineer sent me a list of GM sensors, showing part numbers, resonant frequencies, parallel load resistance, and mounting style. At the time, they were producing sensors in these frequencies: 5.2kHz, 6.0kHz, and 7.0kHz.
So would you conclude bore size is the criteria we should be concerned with in selecting the subject??? If using the above criteria, 110 mm divided by 25.4 mm/inch equals 4.33”. Standard bore for the Caddy 500 is 4.300”. If so, I still need to determine the proper sensor for a Cadillac 500 engine.
What is that part number or what other year, make, and model engine(s) are in that ballpark???
Paul Bartz
Kalamazoo MI
78 Royale Rear Twins
Emery Stora
Jun 19, 2010, 4:40:05 PM6/19/10
to gmcm...@googlegroups.com, Bartz Paul
On Jun 19, 2010, at 1:00 PM, Paul Bartz wrote:
Anyone have words of wisdom on choosing the subject (e. g. is there any relation
to the engine displacement vs. what sensor to use)??? If not, are there any
technical differences between the various ones???
For those who are utilizing the sensor, what part number did you use???
Paul
I have been using the AC/Delco 213234 is also sold as a KS7T or Airtex 5S2158. The last I knew Bob Drewes was also using it. Many GMC vehicles including the 5. L 350 engine in a 1993 Buick Roadmaster Estate to the 1989 GMC K3500- truck with a 7.4 L engine use it.
Emery Stora
77 Kingsley
Santa Fe, NM
Emery Stora
Jun 19, 2010, 8:18:31 PM6/19/10
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PLEASE NOTE THAT I PUT IN THE WRONG NUMBER FOR THE AC/DELCO
IT SHOULD BE #213-324
EMERY STORA
John Biwersi
Jun 21, 2010, 8:20:38 AM6/21/10
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Gentlemen,
Sometime ago I talked to John Pizzuto from J&S Safeguard about knock selection for 455 Olds and 500 Cad engines and he guided me to Dave at Precision Automotive Research in Chicago. Dave believes that the natural knock frequency of typical automotive gasoline engines is primarily related to bore and mildly related to stroke and combustion chamber height. I supplied him with dimensions for both the 455 Olds and the 500 Cad since my plan was to first use the sensor on my 455 for knock notification only and eventually use the same sensor to signal a 7730 ECM on a 500 Cadillac with MPI. Dave estimated the frequency on the 455 to be 6.5 Kilohertz. So he recommended a sensor which gets the best response for frequencies between 5.5-6.4 Kilohertz which is close to his estimate. The natural frequency of the Cadillac 500 will be less than 6.5 Kilohertz because of it's larger bore so this sensor would be good for both of my engines. One of his comments was that the knock sensor is looking for the "echo" across the bore. With that statement he recommended that the ideal location for the sensor was near the head surface of the block. That obviously is a challenge with exhaust manifolds so one must do the best you can with that in mind. The goal is to detect the knock sound and avoid noise from valve trains, timing chains etc. The GM number for the sensor that he supplied me for the 5.5-6.4 Kilohertz is 12591625. The bottom line is if one is attempting to get as much power and milage from fuel with a typical automotive gasoline engine it requires the maximum timing advance which may not be obtained if a knock sensor is incorrectly signaling a ECM. I think that it is a safe bet, that GM would not have gone through the effort of various knock sensors if they could have obtained milage goals with a one size fits all sensor.
John Biwersi
Maplewood MN
78 Royal Center Kitchen
Ken Henderson
Jun 21, 2010, 12:59:38 PM6/21/10
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Paul,
Ken H.
The bottom line question then: Where have you mounted your Cad500 knock sensor? Mine's on a 3/8" x 1" x 1-1/2" adapter bolted into a spare threaded hole above the right axle idler bearing mount. I haven't run it enough yet to have a feel for whether that's a good location.
Ken H.
On Mon, Jun 21, 2010 at 8:20 AM, John Biwersi <jbiw...@mac.com> wrote:
... One of his comments was that the knock sensor is looking for the "echo" across the bore. With that statement he recommended that the ideal location for the sensor was near the head surface of the block. That obviously is a challenge with exhaust manifolds so one must do the best you can with that in mind...John Biwersi
George Beckman
Jun 21, 2010, 11:47:41 PM6/21/10
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John,
I ran your numbers and was able to find both a GM and Delco cross reference. Unfortunately, I could not find a cross to the O'Reily's I put on, which was for a 454. Same cubes but different cylinder configuration. Seems to work as expected, but it makes one wonder if it is correct and if it is mated to the proper ESC unit. Of course, there never was a knock sensor for a 455 Olds.
On Jun 21, 2010, at 5:20 AM, John Biwersi wrote:
The goal is to detect the knock sound and avoid noise from valve trains, timing chains etc. The GM number for the sensor that he supplied me for the 5.5-6.4 Kilohertz is 12591625. The bottom line is if one is attempting to get as much power and milage from fuel with a typical automotive gasoline engine it requires the maximum timing advance which may not be obtained if a knock sensor is incorrectly signaling a ECM. I think that it is a safe bet, that GM would not have gone through the effort of various knock sensors if they could have obtained milage goals with a one size fits all sensor.
John Biwersi
Jun 22, 2010, 8:08:59 AM6/22/10
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Ken,
My 500 Cad block is in the basement buried in boxes of parts so I'm no help now for location for the knock sensor on that engine. On my 455, which is in the coach, I mounted the sensor in a large rectangular boss located at the top of the right front corner of the block forward of the right hand exhaust manifold. With the size of this boss I had no fears in drilling and tapping a horizontal hole for the sensor.
John Biwersi
Maplewood, MN
3.21 final drive dude
John Biwersi
Jun 22, 2010, 8:17:18 AM6/22/10
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George,
It sure would be interesting to learn if there was a difference with the GM 12591625 sensor. I just sent another post as to what I think is a good mounting location on the 455. What was the Delco number for this sensor?
John,
Ken Henderson
Jun 22, 2010, 8:17:33 AM6/22/10
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John,
Ken H.
Don't know why I was thinking you'd installed a Cad 500.
I'm having trouble visualizing where you drilled and tapped a hole in a 455 head that would be better than one of the existing 3/8"-16 holes already at each end of every one of them.
Ken H.
John Biwersi
Jun 22, 2010, 8:23:53 AM6/22/10
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Ken,
The boss is part of the block casting just below the head surface on the right hand side of the block, not on front surface.
John
George Beckman
Jun 22, 2010, 8:51:27 AM6/22/10
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John,
That is the trouble. I spent about an hour trying to cross reference the GM number with what I found at O'Reily's. Even the application list for the GM number would help. My sensor seems to be the one for 454, 350 and a 262. I have not looked up the bore on the 350 and 262 but am guessing that they are similar. The 262 is a V6 and the 350 I am guessing is a much shorter stroke.
On Jun 22, 2010, at 5:17 AM, John Biwersi wrote:
It sure would be interesting to learn if there was a difference with the GM 12591625 sensor. I just sent another post as to what I think is a good mounting location on the 455. What was the Delco number for this sensor?
Ken Henderson
Jun 22, 2010, 10:13:27 AM6/22/10
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I had trouble cross referencing that PN also. Here's the best I've found. I didn't take it any further, trying to cross the crosses or find other applications.
It's sort of a curious one though, because IIRC, the 3.8L engine has a bore of 3.8" -- not very close to the 455 or 500.
Randy Van Winkle
Jun 22, 2010, 10:37:40 AM6/22/10
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The 262 V6 (4.3 liter) is from an Astro Van, C10 pickup, and in several
other applications. It is essentially a 350 block with 2 cylinder
lopped off. The bore on these are 4.125 but there are some variations
in the 350 family. The 454 had a 4.251 in (108.0 mm) bore.
The 455 is 4.126 so I think this would be the appropriate sensor/esc
combination. Looking up the sensor on the OReilly's site, I find this
sensor crosses to 454, 350, and 262 engines. The Cad 500 with around
4.3 in bore will have a slightly less frequency characteristic but this
sensor may still work well. My 403 is 4.35 in bore, about the same as
the Cad 500 - I used the sensor/esc combination from an Astro Van (easy
to extract from a donor) and it seems to be working, however, if any of
you Cad guys find a better sensor tuned for the larger bore, then I
would like to get that information. As George mentioned earlier, I
mounted my sensor in the water jacket with the thought that sound
travels well in water. Besides, GM mounted many of their sensors in
the water jacket also.
Randy (looking for the perfect frequency - what?)
'77 Eleganza II "403"
Randy (looking for the perfect frequency - what?)
'77 Eleganza II "403"
Gordon
Jun 22, 2010, 11:00:43 AM6/22/10
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George;
The bores on the 262 V6 and 350 V8 are identical at 4.125. I don't remember the stroke but I can do the math if you need?
Gordon
The bores on the 262 V6 and 350 V8 are identical at 4.125. I don't remember the stroke but I can do the math if you need?
Gordon
-- "There is still time to enjoy your childhood while playing in a bigger sandbox!"
Gordon
Jun 22, 2010, 11:20:56 AM6/22/10
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Randy;
I am guessing that most of the 455's are 4.156 bore by now. I wonder how critical the match of a knock sensor is to the ultimate mpg?
Gordon
I am guessing that most of the 455's are 4.156 bore by now. I wonder how critical the match of a knock sensor is to the ultimate mpg?
Gordon
On 6/22/2010 7:37 AM, Randy Van Winkle wrote:
The 262 V6 (4.3 liter) is from an Astro Van, C10 pickup, and in several other applications. It is essentially a 350 block with 2 cylinder lopped off. The bore on these are 4.125 but there are some variations in the 350 family. The 454 had a 4.251 in (108.0 mm) bore. The 455 is 4.126 so I think this would be the appropriate sensor/esc combination. Looking up the sensor on the OReilly's site, I find this sensor crosses to 454, 350, and 262 engines. The Cad 500 with around 4.3 in bore will have a slightly less frequency characteristic but this sensor may still work well. My 403 is 4.35 in bore, about the same as the Cad 500 - I used the sensor/esc combination from an Astro Van (easy to extract from a donor) and it seems to be working, however, if any of you Cad guys find a better sensor tuned for the larger bore, then I would like to get that information. As George mentioned earlier, I mounted my sensor in the water jacket with the thought that sound travels well in water. Besides, GM mounted many of their sensors in the water jacket also.
Randy (looking for the perfect frequency - what?)
Surbo
Jun 22, 2010, 12:14:42 PM6/22/10
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Randy & others;
The GM # 12591625 KS is AC-Delco #213-3522, superseds AC-D # 213297.
The '90 1 ton Chev has AC-D #213-324, which I am using and also quoted
by Emery Stora in previous posts.
Go to this link to find what vehicles use the 213-324.
http://tinyurl.com/2ewhn7l
Here is the link for the info on the 213-3522
http://tinyurl.com/2ewhn7l
Bob Drewes w/GM TBI
> >http://www.pggp.com- Hide quoted text -
>
> - Show quoted text -
The GM # 12591625 KS is AC-Delco #213-3522, superseds AC-D # 213297.
The '90 1 ton Chev has AC-D #213-324, which I am using and also quoted
by Emery Stora in previous posts.
Go to this link to find what vehicles use the 213-324.
http://tinyurl.com/2ewhn7l
Here is the link for the info on the 213-3522
http://tinyurl.com/2ewhn7l
Bob Drewes w/GM TBI
>
> - Show quoted text -
Surbo
Jun 22, 2010, 12:24:21 PM6/22/10
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Correction from Surbo;
Make the link to the 213-324 this one;
http://tinyurl.com/29y4m77
Bob Drewes w/GM TBI
> > >http://www.pggp.com-Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
Make the link to the 213-324 this one;
http://tinyurl.com/29y4m77
Bob Drewes w/GM TBI
>
> > - Show quoted text -- Hide quoted text -
Randy Van Winkle
Jun 22, 2010, 1:23:34 PM6/22/10
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Looks like the AC-Deco #213-3522 is for a 3.8 V6 which is a 3.8 in
bore. The #213-324 is for the 262, 350, and 454 which would be close to
the same bore as the 455.
bore. The #213-324 is for the 262, 350, and 454 which would be close to
the same bore as the 455.
Randy (wondering if there was another part number for a larger bore (at
least 4.3) engine)
'77 Eleganza II "403"
Randy Van Winkle
Jun 22, 2010, 1:50:00 PM6/22/10
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Gordon,
Probably more critical to the life of the engine :-)
If the knock sensor is working well for the engine, then you can be a
tad more aggressive with spark with some confidence that the ECM will
"protect" the engine. However, I would not rely on the KS except for
the first time. I think that once you see some knocks in a particular
RPM/MAP cell, I would drop the SA in those cells a couple of degrees.
To me, that is one of the best things about the EBL - that you can tweak
the SA based on how your particular engine behaves. Each engine is
going to be different as to when they will knock and how much SA they
can tolerate. What we are really after is to have the peak pressure in
each cylinder to occur at 14 degrees ATDC. If we could achieve that at
all RPM/MAP conditions then we would always get the optimum performance
from the engine. So SA is related to how fast the flame front
proceeds. Unfortunately, the designs of the 60s and 70s had a fairly
slow flame front so we need quite a bit of SA to achieve Peak Pressure
at 14 * ATDC. Consequently, there is more time for detonation to take
place. Modern engines have a faster flame front thus can run less SA
and therefore, less time for detonation to take place.
Randy (wondering how we could tell when peak pressure occurs without a dyno)
'77 Eleganza II "403"
Terry Taylor
Jun 22, 2010, 1:58:58 PM6/22/10
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OK, Presuming that I get one of these knock sensors, is the knock sensor
module that
I ahve (part # 16022621) the right one to use with this sensor?
module that
I ahve (part # 16022621) the right one to use with this sensor?
On 6/22/2010 9:14 AM, Surbo wrote:
> Randy& others;
Paul Bartz
Jun 22, 2010, 2:16:58 PM6/22/10
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My 2009 Silv-O-Lite piston catalog gives the following bore sizes:
CID Inches
262 4.000
350 3.800 and 4.000 versions
403 4.351
454 4.250
455 4.125
500 4.300
As you’ll recall, a chart from the early 1990-01-01 published SAE Technical Paper 900488, Combustion Knock Sensing: Sensor Selection and Application Issues, authored by Steven M. Dues, Joseph M. Adams, and George A. Shinkle: Delco Remy Div, General Motors Corp, shows that the fundamental frequency of a 75mm (2.952”) bore is about 7kHz, a 94mm (3.700”) bore is about 6.0 kHz, while that of a 110mm (4.330”) bore is about 5.2kHz.
At the time, it was stated that GM was producing sensors in these frequencies: 5.2kHz, 6.0kHz, and 7.0kHz and I haven’t found any info so far on what variety of frequencies(s) today’s sensors are produced.
From the foregoing, it looks like we want a knock sensor that is tuned to the 5.2kHz resonant frequency, specified above for the bore size of 4.330”, of which the Chevy 454 cid engine in the above chart is closest.
In researching the type of knock sensor specified for the Chevrolet 454 cid pickup engine, by using Wells Mfg website, they show the following variety:
Year Wells P/N
1987-90 SU154
1991-95 SU169 (auto trans)
1996-00 SU1122
I contacted Wells to find out what the difference is among the above three sensors. Initially they could not verify if my suspicions of thread size and design resonant frequency differences were correct. However, the rep asked if I could e-mail him, which I agreed to do, the information I’ve researched and he would look for whatever they have available and may be able to e-mail drawings, etc. He went on to say that it’s entirely possible that the OEM’s may not have even provided them any engineering design data. I’ll share his response once received.
Paul Bartz
Kalamazoo MI
78 Royale Rear Twins
George Beckman
Jun 22, 2010, 4:36:27 PM6/22/10
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I don't know, either Gordon, but I guess time will tell. Right now Randy tells us he is running very advanced with out excessive knocks with the accompanying retardation. Our coach rarely gets a count, unless it is stressed on a major hill. When running at 60 mph and giving it gas when starting up a hill will quickly register knocks. Tomorrow's trip to the mountains when I can easily look at the EBL Knock table will tell us quite a bit.
But, it must be true that if you had a knock sensor that was overly sensitive it could cause you to run with the spark too retarded and mess with mpg. So far mine seems to count when we begin to hear pings. That's what I want... retard when it starts to ping. Of course we don't hear them all, that is for sure.
On Jun 22, 2010, at 8:20 AM, Gordon wrote:
I wonder how critical the match of a knock sensor is to the ultimate mpg?
Bruce Hislop, Perth Communications
Jun 22, 2010, 4:42:17 PM6/22/10
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I haven't upgraded yet, but I was wondering if the knock counter on the WUD rolls over now as expected.
My counter rarely registers any more knocks once the noise of the starter etc is done at startup.
My counter rarely registers any more knocks once the noise of the starter etc is done at startup.
Bruce Hislop
Perth Communications
br...@perthcomm.com
Sent from my Blackberry Curve
From: George Beckman <gbec...@pggp.com>
Sender: gmcm...@googlegroups.com
Date: Tue, 22 Jun 2010 13:36:27 -0700
To: <gmcm...@googlegroups.com>
ReplyTo: gmcm...@googlegroups.com
Subject: Re: [GMCMH-EFI] Knock Sensor
George Beckman
Jun 22, 2010, 4:45:17 PM6/22/10
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Good work, Paul. This is some major information. Makes me think that I am OK as I am. As you said, hard to know what is being produced today and how faithfully the frequency specs are built into new sensors. I suppose we could hope that technology has improved and that sensors have a wider range. Hmm.
Gordon
Jun 22, 2010, 9:05:55 PM6/22/10
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Randy;
The limiting factor on lean mixture is the slowing down of the flame
front and the need to advance the SA to compensate.
Gordon
The limiting factor on lean mixture is the slowing down of the flame
front and the need to advance the SA to compensate.
Gordon
Randy Van Winkle
Jun 23, 2010, 7:24:44 AM6/23/10
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Gordon,
That's why I have my total advance at 47 degrees when in lean cruise.
So far, that seems about right for my engine. The EBL has a table that
allows you to bump SA when in lean cruise. I'm bumping by about 4.5
degrees when at 17.2:1 AFR.
Randy (thinking I'm close but still experimenting)
'77 Eleganza II "403"
George Beckman
Jun 23, 2010, 10:09:13 AM6/23/10
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Randy sent me his tables a couple of weeks ago. Today is the first time the coach has been out. We will see what this kind of advance does on a 455 pulling 3.07 gears. I will not be towing, but will have plenty of hills to put it to the test. His table is 3+ degrees advanced from what I had been using. I am going to install it in slot 7 and be ready to go back to what I had if we start hearing pinging. I will watch the WUD spark table and perhaps try an area tune. I sort of hate to do that, as when you graph Randy's table it is a pretty graph. *smile*
Prediction: When I start to pull the hill we are going to see some major knock counts. It is not overly hot, probably about 88 when we hit the grade.
On Jun 23, 2010, at 4:24 AM, Randy Van Winkle wrote:
That's why I have my total advance at 47 degrees when in lean cruise. So far, that seems about right for my engine. The EBL has a table that allows you to bump SA when in lean cruise. I'm bumping by about 4.5 degrees when at 17.2:1 AFR.
Gordon
Jun 23, 2010, 11:07:11 AM6/23/10
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Randy;
What rpm are you able to run during lean cruise. It seems to me that it
is a big mistake to change to a higher numerical final drive so that
your engine turns at a higher rpm, because you then quickly run into the
limit of lean fuel mixture/slow flame front. At higher rpm, you can not
lean out as the flame front does not advance fast enough to burn the
fuel. The maximum hp, go fast idea, is counter to the economy of lean
cruise, slow rpm.
Some people don't seem to know why a 1200 rpm diesel will pull 50,000
pounds at 8 mpg? Complete combustion takes time and if you turn 3600
rpm you are pumping a lot of unburned fuel.
I don't remember all the numbers but I do remember that the most hp for
the least fuel we could pull in the lab was at 450 rpm, with either gas
or diesel. This was with either a single cylinder or a 4 cylinder Atlas
Engine.
Gordon
What rpm are you able to run during lean cruise. It seems to me that it
is a big mistake to change to a higher numerical final drive so that
your engine turns at a higher rpm, because you then quickly run into the
limit of lean fuel mixture/slow flame front. At higher rpm, you can not
lean out as the flame front does not advance fast enough to burn the
fuel. The maximum hp, go fast idea, is counter to the economy of lean
cruise, slow rpm.
Some people don't seem to know why a 1200 rpm diesel will pull 50,000
pounds at 8 mpg? Complete combustion takes time and if you turn 3600
rpm you are pumping a lot of unburned fuel.
I don't remember all the numbers but I do remember that the most hp for
the least fuel we could pull in the lab was at 450 rpm, with either gas
or diesel. This was with either a single cylinder or a 4 cylinder Atlas
Engine.
Gordon
Randy Van Winkle
Jun 23, 2010, 12:16:34 PM6/23/10
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Gordon,
I have 3.70 Final Drive. I always cruise between 60 - 65 mph which puts
me around 2800 - 2900 RPMs. Engine seems to run well. I don't notice
any missing or backfire and it seems to pull well. I'm almost always
pulling a Jeep which cost about 1 1/2 to 2 mpg the best I can tell. The
way I have my tables set, I gradually go richer as load increase until I
drop out of lean cruise then I'm back at 14.7 and stay there until I go
into Power Enrichment. Based on the WB, it appears that the commanded
AFR I see in the log is very close to what is being monitored. I don't
feel any difference in the engine as I transition through the above AFRs
except that I do notice when PE kicks in. PE is a bigger jump because
I'm going from 14.7 to 12.7 so I feel that change. Also, I have delayed
the engagement of PE some so that I'm not in PE mode with every little
bump in the road (overpasses, small hills, etc).
Randy (not sure 600 RPMs is making that much difference in engine
efficiency - sure pulls better but need an OD)
'77 Eleganza II "403"
Gordon
Jun 23, 2010, 12:30:02 PM6/23/10
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Randy;
Thank you very much for the details. Wouldn't it be nice to have 6 or 8
gears, an OD or 2spd final etc? Life is just a compromise and hopefully
one get close to what is best. Without OD you get to pull your weight
well with a 3.70, but on the flat, you want the 3.07 for a poor man's OD.
GORDON
Thank you very much for the details. Wouldn't it be nice to have 6 or 8
gears, an OD or 2spd final etc? Life is just a compromise and hopefully
one get close to what is best. Without OD you get to pull your weight
well with a 3.70, but on the flat, you want the 3.07 for a poor man's OD.
GORDON
George Beckman
Jun 23, 2010, 4:58:54 PM6/23/10
to gmcm...@googlegroups.com
The first leg of our trip is complete and we are camped in a nice spot. The rig ran beautifully. We ended up going to Shaver Lake, so we did the big hill. It is a two lane fairly straight run for about 5 miles. It is a road made to drive 65 on and so it is a good test of the GMC. Of course I cannot go 65 as this is second gear time. More like 45. Ran the air conditioning the whole climb. Fan clutch on and off and it pulls it down immediately. PE, with exhaust temps hitting 1225. Trans temp did fine. Oil gets hot in this engine and I feel it has poopy oil pressure. At 2900 RPMs once we were really grinding the pressure is about 22lbs. As soon as it cools, it runs more like 35-40. Engine sounds perfect, but it is a PO install and I know nothing about it.
I have a question for our LeanCr advance guard guy, Randy. I am including a diagnostics screen picture of one of my logs, in LeanCr and wonder if your WB jumps around as much when you look at your LeanCr. I wish it didn't do that.
On Jun 23, 2010, at 9:16 AM, Randy Van Winkle wrote:
I always cruise between 60 - 65 mph which puts me around 2800 - 2900 RPMs. Engine seems to run well. I don't notice any missing or backfire and it seems to pull well.
George Beckman
Jun 23, 2010, 5:16:30 PM6/23/10
to gmcm...@googlegroups.com
Randy,
I want to add to Gordon's line of thinking. First, Gordon, I agree about the slow running. I grew up in orange grove county in the LA basin before people and smog did away with orange trees. Most wells were run by single cylinder engines running at 200-400 RPMs. Many were 60's and the king of the valley was a 200. I loved to watch that engine... it ran on natural gas.
So, Randy, I just finished the trip up here with your spark tables, including the LeanCr advance tables. I have not waded through all the logs, but in LeanCr I only see one knock count in three cells. So, 455 does not detonate on wildly advanced tables. I am thinking, detonation is not the only issue here. Making sure we are not getting too much pressure on the upstroke before TDC is a second. Randy, we know that 45+ degrees of spark at 17.4:1 Air Fuel is good because?
I think I know Randy's answer. This is why we need a dyno. Would it not be great to have a rig on a dyno with several bins at the ready, and switch up and down watching what is actually happening. Randy, are you sure you don't want to get a dyno for the guys to play with... you could park your JD tractor out in the elements and put the dyno in the back of your shop handy to the rear roll up. You probably could park your tractor on the dyno, out of the elements, when we are not all there testing our GMCs. Or Bob Drewes, you want a dyno, don't you? Maybe your shop would work? (Of course, guys, I could get a couple of them so we could test two at a time, but I am on the West coast and it would be a hardship for some to drop by, where as middle America would be perfect.)
On Jun 23, 2010, at 8:07 AM, Gordon wrote:
The maximum hp, go fast idea, is counter to the economy of lean cruise, slow rpm.
Some people don't seem to know why a 1200 rpm diesel will pull 50,000 pounds at 8 mpg? Complete combustion takes time and if you turn 3600 rpm you are pumping a lot of unburned fuel.
George Beckman
Jun 23, 2010, 5:20:22 PM6/23/10
to gmcm...@googlegroups.com
Yes, Mobil 1 and I listened carefully to what Miguel said (in his shop) about it. He has called the engineers at Mobil and they say Mobil 1 was not created for our kind of heavy service. He uses the Chevron Delo 400. I would be interested in pros and cons. I think I need to quit fiddling around and the the oil cooler out of the box and onto the coach.
On Jun 23, 2010, at 2:05 PM, Gordon wrote:
George;
I'm just curious if you are running synthetic oil?
Thanks;
Gordon
Randy Van Winkle
Jun 23, 2010, 11:16:21 PM6/23/10
to gmcm...@googlegroups.com
George,
You get the dyno and I will provide the space for it in my barn 8-) Short of that, I think we need to set up a measured course and try different SAs. Checking mpg from the EBL over the measured course would give an idea of the engine efficiency. Need a consistent foot on the pedal. We could burn up a tank of gas pretty quickly running these tests. Would be good info and would answer some of the questions we have. Maybe when you are here this fall (before DeQuoine). Of course, my coach gets to stay in the barn out of the elements.
Why do I think 47 degrees of SA is right? Dunno, but SOP tells me everything is running good. Didn't have a good comparison because the trip the time before this last was without the Jeep. Was getting right at 11 mpg. This last trip was to Johnston's Shut-ins State Park in the Ozarks so lots of back roads and ups, downs, and those dreaded double curve road signs saying you should only go 35 or 45 mph around the curves. BTW, those are always slow for when I'm in the car, but about right for the GMC. Anyway, wasn't in lean cruise very much. Still getting about 8.4 mpg. So, maybe 45 degrees is better, or perhaps 50 degrees? Problem with 50 degrees is I would have to change the initial SA. Leaning the mixture will slow down the flame front so starting the spark earlier will hopefully get close to the peak pressure at the optimum 14 degrees ATDC. You are right, don't want pressure build up before TDC. I think doing our proposed measured course exercise would tell us if we are causing the engine to work against itself.
Randy (wishing I had time to play - where's that dyno?)
'77 Eleganza II "403"
You get the dyno and I will provide the space for it in my barn 8-) Short of that, I think we need to set up a measured course and try different SAs. Checking mpg from the EBL over the measured course would give an idea of the engine efficiency. Need a consistent foot on the pedal. We could burn up a tank of gas pretty quickly running these tests. Would be good info and would answer some of the questions we have. Maybe when you are here this fall (before DeQuoine). Of course, my coach gets to stay in the barn out of the elements.
Why do I think 47 degrees of SA is right? Dunno, but SOP tells me everything is running good. Didn't have a good comparison because the trip the time before this last was without the Jeep. Was getting right at 11 mpg. This last trip was to Johnston's Shut-ins State Park in the Ozarks so lots of back roads and ups, downs, and those dreaded double curve road signs saying you should only go 35 or 45 mph around the curves. BTW, those are always slow for when I'm in the car, but about right for the GMC. Anyway, wasn't in lean cruise very much. Still getting about 8.4 mpg. So, maybe 45 degrees is better, or perhaps 50 degrees? Problem with 50 degrees is I would have to change the initial SA. Leaning the mixture will slow down the flame front so starting the spark earlier will hopefully get close to the peak pressure at the optimum 14 degrees ATDC. You are right, don't want pressure build up before TDC. I think doing our proposed measured course exercise would tell us if we are causing the engine to work against itself.
Randy (wishing I had time to play - where's that dyno?)
'77 Eleganza II "403"
Surbo
Jun 23, 2010, 11:38:45 PM6/23/10
to GMCMH EFI
George Beckman wrote:
>you could park your JD tractor out in the elements <
Are you kidding....there are priorities for 'Green Iron'...don't you
>you could park your JD tractor out in the elements <
know?
Bob D w/GM TBI
George Beckman
Jun 24, 2010, 12:06:05 AM6/24/10
to gmcm...@googlegroups.com
Here is my plan. Find a flat stretch of freeway. Set the cruise and not shut it off. This way we get a fairly consistent peddle between runs. Then we use the Trip screen, resetting it at a certain point and noting the test at another predetermined point. This way we can get a decimal MPG reading for the short run. With a little luck we might be able to note some differences. I am thinking that if we did a down and back test, wind would null out.
On Jun 23, 2010, at 8:16 PM, Randy Van Winkle wrote:
Checking mpg from the EBL over the measured course would give an idea of the engine efficiency. Need a consistent foot on the pedal. We could burn up a tank of gas pretty quickly running these tests. Would be good info and would answer some of the questions we have.
Randy Van Winkle
Jun 24, 2010, 8:37:38 AM6/24/10
to gmcm...@googlegroups.com
Bob,
You got that right! Right now, the only 'green iron' that sits outside
is my T-24 baler. Even the old JD bicycles (1970s vintage) have a spot
inside.
Randy (always needing a bigger barn)
'77 Eleganza II "403"
Randy Van Winkle
Jun 24, 2010, 8:41:03 AM6/24/10
to gmcm...@googlegroups.com
George,
You need to hurry back here so we can get started with the testing :-)
Bob, come on down, we could have a mini-rally :-)
Randy (trying to get the "must-dos" done so I can play)
'77 Eleganza II "403"
On 6/23/2010 11:06 PM, George Beckman wrote:
> Here is my plan.
Wally Anderson
Jun 24, 2010, 8:55:21 PM6/24/10
to GMCMH EFI
I'm not sure what EBL needs for knock signal levels but here is what I
am using.
http://www.viatrack.ca/
It uses a non resonant sensor and they need to know what the bore is
when you order to set the module up for your application. It does have
adjustable sensitivity. Less than $100 and you get something else to
tweak. ;- )
On Jun 19, 2:00 pm, "Paul Bartz" <pba...@earthlink.net> wrote:
> Jim:
>
> Fromwww.eng-tips.com/viewthread.cfm?qid=54276, scroll down to time stamp 28 Jul 03 15:47 (on the right side of the page). He gives a SAE Technical Paper Series 900488, Combustion Knock Sensing: Sensor Selection and Application Issues, authored by Steven M. Dues, Joseph M. Adams, and George A. Shinkle: Delco Remy Div, General Motors Corp. A chart from the SAE paper shows that the fundamental frequency of a 75mm bore is about 7kHz, a 94mm bore is about 6.0 kHz, while that of a 110mm bore is about 5.2kHz. The chart shows a fairly linear relationship of frequency to bore diameter. However, in searching on that item, SAE wants money.
>
> He goes on to say: In the mid '90's, a GM engineer sent me a list of GM sensors, showing part numbers, resonant frequencies, parallel load resistance, and mounting style. At the time, they were producing sensors in these frequencies: 5.2kHz, 6.0kHz, and 7.0kHz.
>
> So would you conclude bore size is the criteria we should be concerned with in selecting the subject??? If using the above criteria, 110 mm divided by 25.4 mm/inch equals 4.33”. Standard bore for the Caddy 500 is 4.300”. If so, I still need to determine the proper sensor for a Cadillac 500 engine.
>
> What is that part number or what other year, make, and model engine(s) are in that ballpark???
> Sent: Saturday, June 19, 2010 12:05 AM
>
> Paul,
>
> from what I have experienced, the displacement is not the factor.
>
> On Fri, Jun 18, 2010 at 7:21 PM, Paul Bartz <pfba...@att.net> wrote:
>
> Anyone have words of wisdom on choosing the subject (e. g. is there any relation
> to the engine displacement vs. what sensor to use)??? If not, are there any
> technical differences between the various ones???
>
> For those who are utilizing the sensor, what part number did you use???
am using.
http://www.viatrack.ca/
It uses a non resonant sensor and they need to know what the bore is
when you order to set the module up for your application. It does have
adjustable sensitivity. Less than $100 and you get something else to
tweak. ;- )
On Jun 19, 2:00 pm, "Paul Bartz" <pba...@earthlink.net> wrote:
> Jim:
>
> Fromwww.eng-tips.com/viewthread.cfm?qid=54276, scroll down to time stamp 28 Jul 03 15:47 (on the right side of the page). He gives a SAE Technical Paper Series 900488, Combustion Knock Sensing: Sensor Selection and Application Issues, authored by Steven M. Dues, Joseph M. Adams, and George A. Shinkle: Delco Remy Div, General Motors Corp. A chart from the SAE paper shows that the fundamental frequency of a 75mm bore is about 7kHz, a 94mm bore is about 6.0 kHz, while that of a 110mm bore is about 5.2kHz. The chart shows a fairly linear relationship of frequency to bore diameter. However, in searching on that item, SAE wants money.
>
> He goes on to say: In the mid '90's, a GM engineer sent me a list of GM sensors, showing part numbers, resonant frequencies, parallel load resistance, and mounting style. At the time, they were producing sensors in these frequencies: 5.2kHz, 6.0kHz, and 7.0kHz.
>
> So would you conclude bore size is the criteria we should be concerned with in selecting the subject??? If using the above criteria, 110 mm divided by 25.4 mm/inch equals 4.33”. Standard bore for the Caddy 500 is 4.300”. If so, I still need to determine the proper sensor for a Cadillac 500 engine.
>
> What is that part number or what other year, make, and model engine(s) are in that ballpark???
>
> Paul Bartz
>
> Kalamazoo MI
>
> 78 Royale Rear Twins
>
> From: gmcm...@googlegroups.com [mailto:gmcm...@googlegroups.com] On Behalf Of Jim Kanomata
> Paul Bartz
>
> Kalamazoo MI
>
> 78 Royale Rear Twins
>
> Sent: Saturday, June 19, 2010 12:05 AM
>
> Paul,
>
> from what I have experienced, the displacement is not the factor.
>
> On Fri, Jun 18, 2010 at 7:21 PM, Paul Bartz <pfba...@att.net> wrote:
>
> Anyone have words of wisdom on choosing the subject (e. g. is there any relation
> to the engine displacement vs. what sensor to use)??? If not, are there any
> technical differences between the various ones???
>
> For those who are utilizing the sensor, what part number did you use???
Ken Henderson
Jun 24, 2010, 9:53:42 PM6/24/10
to gmcm...@googlegroups.com
Thanks for that link, Wally. Lots of interesting information there and in its links.
Ken H.
Perhaps most germane to the discussions here is this statement:
"Also I need know the approximate cylinder bore when ordering. We tune each KnocksenseMS filter so that it better matches the engine. This need not be exact because the filter is deliberately broad in order account for the
variance in knock frequency due to dynamic changes in operating conditions."
variance in knock frequency due to dynamic changes in operating conditions."
That says to me that it's fruitless to obsess too much about which sensor to use -- close is good 'nuff. The 454 sensor is probably about as good as any.
The KnockSense should be introduced to the broader GMC community; it's a very reasonable price for what's likely to be a pretty good knock indicator.
Ken H.
Wally Anderson
Jun 24, 2010, 10:18:56 PM6/24/10
to GMCMH EFI
Ken, I have this quick and dirty frequency calculator link that I
forgot to include.
http://www.phormula.co.uk/KnockCalculator.aspx
forgot to include.
http://www.phormula.co.uk/KnockCalculator.aspx
George Beckman
Jun 25, 2010, 10:32:28 AM6/25/10
to gmcm...@googlegroups.com
Randy,
So far I am pretty impressed with your advance schedules. I have two questions upon using the new settings:
What setting do you have for Max Advance?
Has your coach ever died shortly after startup? Perhaps only partially warmed up. Since I plugged in your tables, my coach has died twice right after startup. Once in the yard as I was putting it in drive and once at the gas station immediately after starting.
Randy Van Winkle
Jun 25, 2010, 11:38:59 AM6/25/10
to gmcm...@googlegroups.com
George,
I did not change Max Advance because that is set at 42 degrees which is the max you can electronically advance the timing reliably. Remember, the SA table shows the SA plus any adders (lean cruise) shows the SA at the crank. So whatever is calculated with the initial advance added (6 degrees) gives you the total SA. So if the table calls for 44 and the lean cruise is adding 4 then you will have 48 degrees at the crank.
I generally do not have any problems starting but have had a couple of times when it starts but then dies. This happened once back in April when on our trip home from your place so was before the SA changes - just starting out so only partially warmed up. Then it occurred during this last trip. This last time, it was really hot and I had just filled up. Seemed like it was starved for fuel but have not come to any conclusions yet. I also had that happen once back on the original 7747 setup when we had gone to Tulsa in July (temps over a 100) and I stopped to fill up. Didn't want to start and run without a lot of coaxing.
Randy (thinking this may be heat related)
'77 Eleganza II "403"
I did not change Max Advance because that is set at 42 degrees which is the max you can electronically advance the timing reliably. Remember, the SA table shows the SA plus any adders (lean cruise) shows the SA at the crank. So whatever is calculated with the initial advance added (6 degrees) gives you the total SA. So if the table calls for 44 and the lean cruise is adding 4 then you will have 48 degrees at the crank.
I generally do not have any problems starting but have had a couple of times when it starts but then dies. This happened once back in April when on our trip home from your place so was before the SA changes - just starting out so only partially warmed up. Then it occurred during this last trip. This last time, it was really hot and I had just filled up. Seemed like it was starved for fuel but have not come to any conclusions yet. I also had that happen once back on the original 7747 setup when we had gone to Tulsa in July (temps over a 100) and I stopped to fill up. Didn't want to start and run without a lot of coaxing.
Randy (thinking this may be heat related)
'77 Eleganza II "403"
Randy Van Winkle
Jun 25, 2010, 11:44:07 AM6/25/10
to gmcm...@googlegroups.com
Yes, I have been pleased -- so far. I haven't done any long hard pulls
- just short hard pulls. So I'm not sure how it will hold up when
heading West again. My plan now is to watch for knock counts and tweak
a little in those cells where knocks occur. Our testing in September
should help to see if we are close to optimum.
- just short hard pulls. So I'm not sure how it will hold up when
heading West again. My plan now is to watch for knock counts and tweak
a little in those cells where knocks occur. Our testing in September
should help to see if we are close to optimum.
Back to fixing the JD 24T baler so I can finish baling this year - about
150 bales to go. Poor old thing is about worn out - me too!
Randy (can we dial in too much SA? -- Where's that dyno?)
'77 Eleganza II "403"
George Beckman
Jun 25, 2010, 12:03:07 PM6/25/10
to gmcm...@googlegroups.com
My engine started again instantly, but required a bit of gas to keep it running. After a few seconds, it seemed to realize it was supposed to go and all was well.
On Jun 25, 2010, at 8:38 AM, Randy Van Winkle wrote:
Didn't want to start and run without a lot of coaxing.
George Beckman
Jun 25, 2010, 12:22:53 PM6/25/10
to gmcm...@googlegroups.com
Interesting. I was looking at mine and it is set at almost 45. I don't remember ever fiddling with that. I will put it back to 42 for the run home. Going from 5,000+ feet to 147 should allow quite a bit of DFCO and LeanCr.
On Jun 25, 2010, at 8:38 AM, Randy Van Winkle wrote:
I did not change Max Advance because that is set at 42 degrees which is the max you can electronically advance the timing reliably. Remember, the SA table shows the SA plus any adders (lean cruise) shows the SA at the crank. So whatever is calculated with the initial advance added (6 degrees) gives you the total SA. So if the table calls for 44 and the lean cruise is adding 4 then you will have 48 degrees at the crank.
Gordon
Jun 25, 2010, 12:38:48 PM6/25/10
to gmcm...@googlegroups.com
I had suggested that the initial advance be set at 8* to allow for a
little more total advance, but 6* was arrived at by consensus.
Gordon
Gordon
George Beckman
Jun 25, 2010, 12:39:11 PM6/25/10
to gmcm...@googlegroups.com
As I fiddle with the few tweaks for the run home, I was looking Launch Mode Parameters in the EBL calibration html document. BobR states two things that peaked my interest. First, he says this is intended to give a slight fuel economy increase and second, with vehicles with automatics it helps the engine spool up against the torque converter. I know this is just fiddling, but wondered if anyone has looked at or tried any changes in these areas? I did a compare with the latest bin Randy sent me and I see no changes there.
What say you, EBL guys?
George Beckman
Jun 25, 2010, 1:37:32 PM6/25/10
to gmcm...@googlegroups.com
I remember that and had 8* in my brain when I stepped up from 0. I had to actually look at our standards. 8* would have been easier because of the little peaks on the timing mark, for those of us who have not taken Bob Drewe' suggestion of creating a timing portal on the bell housing.
I don't know why I have not taken Bob's advice as I brag about his other good ideas I finally adopted. I suppose I am slow to change but never suffer from an unwillingness to gripe about inconveniences my lack of action causes me.
On Jun 25, 2010, at 9:38 AM, Gordon wrote:
I had suggested that the initial advance be set at 8* to allow for a little more total advance, but 6* was arrived at by consensus.
George Beckman
Jun 26, 2010, 12:20:42 AM6/26/10
to gmcm...@googlegroups.com
I would like some thinking on my last log of our return. Coach ran beautifully. So anyone looking can be on the same page, I have an Intake Air Temperature (IAT) installed and am not blending IAT and Coolant Temperature Sensor (CTS) at all.
My Intake is through a Jeep air horn, out the left side and the air cleaner is between the left headlight and the wheel well. I say this because when stopped the differential between IAT and CTS drops, because the nose shell of the GMC gets warm when not moving through the air.
This log was taken after stopping at our favorite strawberry stand on the way into town. There for the log consists of slow driving and several stop lights. Upon playing the log, it came as a rude shock to me when I saw my BLM tables rise to 158 at idle. My tables always run within 2-4 of 128. Sure enough, with the slightest application of gas and the tables drop to 128. Playing the log in the WUD, you can watch the BLM counting from 128 to 158 at a fairly rapid pace at idle.
This leaves me wondering. My IAT is in the chrome tube attached to the Jeep air horn. The IAT is about at Alternator distance from the TBI. I know that at idle, air moves very slowly and I am supposing becomes warmer. However the IAT only creeps up a degree or two C. Is the intake manifold heating up when little air is moving and the resulting air is actually much warmer?
Do I blend IAT and CTS more? If the BLMs needing to suddenly change is related to IAT, I don't see what good it would do to blend more and reduce the effect if IAT. Do I tweak my fuel tables? My brain starts to hurt when several variables begin to come into play. (I am thinking folks will say, "Blend more.")
The .dat file to play back is a zipped file called BackFromShaver4.dat.zip located in our files area:
Randy Van Winkle
Jun 26, 2010, 7:56:53 AM6/26/10
to gmcm...@googlegroups.com
Blend more, at least some a the lower gms/sec. That will help stabilize
the effects of inlet air temps rising during idle.
the effects of inlet air temps rising during idle.
For some reason, I'm not able to download the zip file you uploaded. It
says "the page you navigated to does not exist". This happens with all
the zip files in the Files Section. Other files work OK. Strange?
It is hard to keep the tune where it should be when using IAT. You tune
when air temps are cool, then summer happens and now we have hotter
temps. You say you don't see much change in the IAT temps when at
idle. Mine will increase quite a bit during idle. I measure up in the
jeep air horn.
Randy (not sure about IAT advantages - seems like a good idea)
'77 Eleganza II "403"
Bruce Hislop, Perth Communications
Jun 26, 2010, 8:01:12 AM6/26/10
to Gmcmh-efi google group
George,
My IAT is in the side if a riser tube I made to adapt the Jeep horn to the top of the TBI. From there it goes to a aluminum dryer hose to a cone style air cleaner above the steering box.
My IAT rises maybe 10c in city driving and less than 5c on the hyway. I have a blend of 10% with CTS, but I don't have the laptop to give my exact table.
George have you considered going to Open Loop idle? My understanding is OL idle is common on large engines to give a smoother idle.
My IAT is in the side if a riser tube I made to adapt the Jeep horn to the top of the TBI. From there it goes to a aluminum dryer hose to a cone style air cleaner above the steering box.
My IAT rises maybe 10c in city driving and less than 5c on the hyway. I have a blend of 10% with CTS, but I don't have the laptop to give my exact table.
George have you considered going to Open Loop idle? My understanding is OL idle is common on large engines to give a smoother idle.
Bruce Hislop
Perth Communications
br...@perthcomm.com
Sent from my Blackberry Curve
From: George Beckman <gbec...@pggp.com>
Sender: gmcm...@googlegroups.com
Date: Fri, 25 Jun 2010 21:20:42 -0700
To: <gmcm...@googlegroups.com>
ReplyTo: gmcm...@googlegroups.com
Subject: Re: [GMCMH-EFI] Randy's Super Spark Tables
George Beckman
Jun 26, 2010, 10:07:00 AM6/26/10
to gmcm...@googlegroups.com
First, I uploaded the file as a .dat BackFromShaver4.dat
http://groups.google.com/group/gmcmh-efi/files?hl=en
Here is my dilemma. If the air is warming up... or is warmer than the computer thinks it is, then why is it richening the mixture? Seems like if the temp was higher than reality, it would have less "air" in it and would need less gas.
I probably am thinking about it backwards again. Randy has known me since high school and has experienced this backwards thinking when he used to try to help me with physic formulas.
If you can see the log, it is actually counting up from first moments of idle to say 20 seconds into idle so Randy's theory may be correct, but I thought it would have to lean it out because of less air than reported.
On Jun 26, 2010, at 4:56 AM, Randy Van Winkle wrote:
It is hard to keep the tune where it should be when using IAT. You tune when air temps are cool, then summer happens and now we have hotter temps. You say you don't see much change in the IAT temps when at idle. Mine will increase quite a bit during idle. I measure up in the jeep air horn.
George Beckman
Jun 26, 2010, 10:09:06 AM6/26/10
to gmcm...@googlegroups.com
Open loop may work. I like CL because many times I am between 0 and 6000 feet, and like the altitude compensation.
On Jun 26, 2010, at 5:01 AM, Bruce Hislop, Perth Communications wrote:
My IAT rises maybe 10c in city driving and less than 5c on the hyway. I have a blend of 10% with CTS, but I don't have the laptop to give my exact table.
George have you considered going to Open Loop idle? My understanding is OL idle is common on large engines to give a smoother idle.
Randy Van Winkle
Jun 26, 2010, 11:02:43 AM6/26/10
to gmcm...@googlegroups.com
Well.......I was thinking you said you went from 128 to 158 for the
BLMs. 158 means you are much leaner than you were before. This may be
where the backward logic comes in??? :-)
BLMs. 158 means you are much leaner than you were before. This may be
where the backward logic comes in??? :-)
Randy (just thinking....)
'77 Eleganza II "403"
George Beckman
Jun 28, 2010, 11:19:30 PM6/28/10
to gmcm...@googlegroups.com
I have further report. I must admit that what I think I have found was due to Randy's expertise. I had noted in my comments about my last log, that I found the engine idling at high BLMs. Because I was not blending the IAT with the coolant temp, we think that will help. But as I looked at the log going through town, I notice I was in Open Loop until I had been at a stop for a while.
Because I was embarrassed that I could not figure out why it was going into open loop in the first place? I marked a number of lines in excel were the shift was happening and sent it to Randy.
DFCO. Doh! I keep forgetting that DFCO, PE, LeanCr are technically open loop. But then why when throttle was closed and RPMs were at idle speeds was I not in Open Loop? I looked at the MPH setting for "idle". It was set at 4 mph. But, with my 3.07 gears and our 2200 RPM stall torque converters, my rig can hit idle speeds at 15 mph when in DFCO. At 1000 RPMs the engine restarts, and it is in "idle" but the MPH parameter has not been reached, so I am left in no man's land, not in DFCO, but not technically at "idle" even though the engine is idling.
So, I have raised the coach speed from four to 14 mph for the idle threshold. There are other parameters, but I am including my settings for your scrutiny. My thinking is that I will drop our of DFCO at 15 mph and go into idle and closed loop at 14 mph.
On Jun 26, 2010, at 7:09 AM, George Beckman wrote:
pen loop may work. I like CL because many times I am between 0 and 6000 feet, and like the altitude compensation.
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