Howell/Holley EFI — constant Codes 33 and 34

[Tiago Soromenho]

Hi everyone! Finally made it to the EFI Google Group instead of FB! (Randy will be happy! ; )

I don’t know if I have a problem with my EFI but I suspect I do:  My ECM (1227747) keeps giving a code 33 and code 34 error. Sometimes it’s just code 33 (MAP high) but lately it’s been code 33 and 34 (MAP low).  I have checked the code in both the ALDLdroid tablet app connected to the ECM by a Bluetooth adapter (very convenient) as well as the old school way, shorting ALDL pin A to Pin B and reading the codes (12, followed by 33 and 34)

I thought it was a faulty MAP sensor so I went and got a new one. No difference. 

On either the new or old MAP sensor, if I connect the three-prong harness and a rubber line, and either suck or blow on the tube, I can get the engine to slow or speed up (just a bit, but noticeable) but the error codes remain. 

I’ve tried to clear codes (unpower ECM for 10+ secs) but codes return a few seconds after I turn on engine, and remain even after a minute  

The tube to the TBI seems fine. It is connected to a lower port facing the distributor. It is not Teed into anything else. Straight to sensor. 

Not sure what else I should be looking for / trouble shooting. I looked at the instructions (https://www.dropbox.com/s/2f3vi6y6u699wxi/Howell%20Electronic%20Fuel%20Injection%20Manual.pdf?dl=0) and the charts on pages 35 and 36, but neither seemed to help.  

I’m thinking the issue might be one of the three-wire harness wires is broken. I can test wash lead with a multimeter (for voltage, open circuit, ground state, hot/read voltage, etc.  But I’m not sure what I’m testing and what the three leads (labeled A, B and C) are for. Partial engine and ECM setup photo attached for reference.. I can provide more if needed. 

Any ideas or prior experience on how to resolve issue much appreciated!

And glad to have finally made it here!

Cheers all,

-Tiago

[Randy Van Winkle]

First, the vacuum line to the TB should be attached to the right hand vacuum port on the front of the TB and that rear port plugged. There was an update at some point from Howell, I think, that made this change. Vacuum needs to be full manifold vacuum all the time. The back one may not be. 

Here is the wiring diagram. http://dynamicefi.com/EBL_Drawings.php    part way down is the MAP sensor. A is ground (shared with the tps) so ohm that.  C is 5v reference so check for that with key on. B is the signal so check for 4.9 v with key on and around 2 running. Voltage will vary depending on engine load. Next, using the schematic I would check continuity between map pin outs and the corresponding pin outs on the ECM. If all that checks out you either got a bad new sensor (it happens) or there is a problem with the ECM. If the latter, maybe you can find someone local with a 7747 ECM that you could swap for a test. Just pull your chip and put it in the borrowed unit. There are two chips - the bigger of the two is the one you want. If you have access to a junk yard then you can get one at a reasonable price. ECMs rarely go bad but stuff happens. 

Randy

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[BruceHislop]

I posted this earlier to using "reply" but it went only to Tiago


-------- Forwarded Message --------
Subject: Re: [GMCMH-EFI] Howell/Holley EFI — constant Codes 33 and 34
Date: Sat, 11 Jul 2020 08:35:15 -0400
From: BruceHislop <bhis...@gmail.com>
To: Tiago Soromenho <tiago.s...@gmail.com>



Tiago,

First go here and download the wiring diagrams from this page:
http://dynamicefi.com/EBL_Drawings.php

From the wiring diagram you can see that:
A = ground
B= Map signal
C= +5 volt power

So at the ECM end, using a volt meter at pin C11 you should read a
voltage between 0 and 5 volts depending on engine vacuum. Actually more
like 1-4 volts.  I don't know which way is high and low vacuum voltage wise.

If it is stuck at low voltage, suspect the +5 volt line.  If it is stuck
at high voltage, suspect the ground line.  Note the MAP and Throttle
Position share the same +5 volt line.

The great thing with the EBL is the What's Up Display (WUD).  It show
the sensors as bar graphs.


Bruce Hislop

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[Tiago Soromenho]

Thanks Randy and Bruce for the link to the diagrams and the description of what the three pins are. That will really help tomorrow! I’ll post more on results and if I manage to trace the fault. I do have an extra 7747 module and both the old anew MAP sensors. And there’s always a chance that both the old and the new are bad.  I suspect the fault is in the wiring, but for the result of blowing it sucking on the tube going to the MAP sensor (both old and new) and that seemingly affecting the engine speed at idle. Which would mean that the sensor is doing its job and the ECM is picking the signal up, responding, and affecting the throttle or timing. But if so, why the error codes?  Argh. I’ll post the test results on the connector pins tomorrow.  Good night!

[BruceHislop]

Tiago,

I suspect the code is thrown when the ECM reads either near zero or +5
volts (max low or max hi) after it reads the engine is running by the
distributor input pulses.

Reading the sensor output voltage with a voltmeter is not easy. You
would need to read the voltage from the wire side of the ECM connector. 
Here is a link showing how the connector comes apart.
 http://dynamicefi.com/RePinHowTo.php

There is a retaining "comb" on each side of the connector. carefully
remove that and you should be able to get your voltmeter on the contact
from the wire side.  It should read between ~0.5v and 4.5v and vary with
engine vacuum while the engine is running.

FYI, I would not throw the Howell system out in favour of one of the new
systems.  It is a very reliable system with readily available parts at
any auto store.

Bruce Hislop

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[Bill Van Vlack]

The ALDLdroid Android app Tiago uses reports the MAP voltage... (See Tiago's FB comment with a screen shot of his ALDLdroid dash)  I presume that is reporting the value decoded by the same A/D that feeds the ECM logic, in which case it should represent the value that generates the code, and the voltage on the input pins.

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[James Hupy]

Geez, you guys driving a 40 year old dinosaur cast iron monster with combustion chambers and valves, ports, manifolding all engineered before there were semi- conductors or chips, all designed around leaded fuels, are expecting a whole lot from your electronic engine management systems. 

     If it starts and continues to run on the swill that passes for motor fuels today, you should rush right out and buy a lottery ticket, because you are lucky ducks.

Just sayin'

Jim Hupy

Salem, Oregon 

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[Tiago Soromenho]

Hi Randy,

When you mention that the vacuum line (to the MAP sensor, right?) should be attached to the right hand vacuum port on the right side of TB. Are you talking about moving to port A or B in the attached photo? 

Thanks,

-Tiago 

[Tiago Soromenho]

Correct. If you look at the attached screen shot, you can see the MAP values (y axis) over time (x axis) (the color/z axis are the RPM). It looks like the MAP is sensing vacuum/pressure and sending voltage (2.82 to 4.02) to the ECM. This two sets of readings were taken when I drive up to meet with Luke Mahon and Jason Stryker who had just driven back from the Co-op, and then over to Luke’s RV storage place, using to “old” MAP sensor (which might not have been defective at all then...?

[Tiago Soromenho]

Forgot to attaché the photos to previous reply... 😳

Attached now. 

[Tiago Soromenho]

Hahahaha... I often think the same thing, when I read about other issues other owners have. But it’s also like arguing about when email doesn’t work right when there’s pen and paper and the postal service that still work fine. We could, if we wanted, do this exchange by own and paper and stamps... but this is much more efficient, isn’t it. I see the EFI and especially the gauges and monitoring as early warning systems: it works, yes, but if something’s not right, for how long? I’d rather troubleshoot from my driveway than on the side of the road (if so lucky) in the middle of nowhere.., ; )

[Tiago Soromenho]

Quick mid-diagnostic update: with key off I read two grounds (each edge pin in the harness) and no reading in the middle pin.  With key on, engine off, one edge pin is ground, the other has steady 5v.  See photos. 

Going to now figure out how to read output from MAP itself and then where at the plug into the ECM. My feeling is that there’s nothing wrong with MAP sensor nor with wires. 

But if so, why the error codes still...? 🤔 one thing at a time...

[James Hupy]

I am not arguing at all. I install and service EFI systems, and the Howell with EBL is the top of the heap. The ability of the GM computer combined with Bob R's EBL has opened a whole new list of possibilities to an obsolete vehicle. It is "NEARLY ALWAYS" spot on out of the box, and will self teach until it is. A whole lot of the time, better than  the humans who are messing around with it. But, when you change stuff like cams and headers and gearing, a bit of tweaking can sometimes be very helpful. This system gives you the ability to just install a binary file with amazing results. But the old adage "If a little bit is good, then more is better" does not apply at all here. Baby steps are normally all that are required, not giant leaps. And just change one thing at a time, then check for results.

Jim Hupy

Salem, Oregon 

On Sun, Jul 12, 2020, 9:49 AM Tiago Soromenho <tiago.s...@gmail.com> wrote:

Hahahaha... I often think the same thing, when I read about other issues other owners have. But it’s also like arguing about when email doesn’t work right when there’s pen and paper and the postal service that still work fine. We could, if we wanted, do this exchange by own and paper and stamps... but this is much more efficient, isn’t it. I see the EFI and especially the gauges and monitoring as early warning systems: it works, yes, but if something’s not right, for how long? I’d rather troubleshoot from my driveway than on the side of the road (if so lucky) in the middle of nowhere.., ; )

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[Tiago Soromenho]

James: Totally agreed. And the EBL system does seem to have many advantages over what I have now. Now that I’m back to going to FL and after talking to Jason Stryker from Co-op, I’ll take the coach there for evaluation, and see what Bounds says. I’m not sold on the newer sniper / FiTech FIs...

Randy/Bill: Update on that MAP sensor. I Gerry-rigged jumper wires to read the output of the MAP sensor and it outputs 4.8v with key on, engine off. Once I turn engine on (cold engine, idle mode) output is 2.8v. I can see the same readings on the ALDLdroid app, so that seems to indicate the ECM is receiving the voltage output, and relating it to the tablet. That eliminates any theory that there’s a break in the electric wires in the harness...

So that goes back to original question: why the error codes if the MAP sensor is fine, the wires are fine, and the ECM gets and passes on the voltage output.  Going to rummage through a couple ECM units Don Virta left with me to see if changing the chip (if I have another) will change anything, in case the chip is defective...

[Bill Van Vlack]

Move it to port A (passenger side) in your photo below. Port B is ported vacuum (center vacuum port on front of TB). The port on the driver's side is also manifold vacuum.

Here is a photo. Either manifold vacuum will work, but in your case the 'right' one in this photo is already used.

[Tiago Soromenho]

I do see your attached photo. I’ll move the line (if it reaches. They didn't leave much extra length to play with...)

Also I have two extra PROMs. The one I have on right now (see photo) seems to be a custom made one?  The other two should still work? One says “Delco ARJT 7489” and the other “ANLW 5489” 

Would it hurt anything to swap the custom one to the Delco one, for example, just to check if that gets rid of error codes? 

-Tiago

202-425-5201

On Jul 12, 2020, at 12:36, Bill Van Vlack <bill.va...@gmail.com> wrote:



I don't know why the photo won't display. I've attached it as a file... maybe that will work.

On Sunday, July 12, 2020 at 10:33:33 AM UTC-7, Bill Van Vlack wrote:

Move it to port A (passenger side) in your photo below. Port B is ported vacuum (center vacuum port on front of TB). The port on the driver's side is also manifold vacuum.

Here is a photo. Either manifold vacuum will work, but in your case the 'right' one in this photo is already used.

On Sunday, July 12, 2020 at 9:28:52 AM UTC-7, Tiago Soromenho wrote:

Hi Randy,

When you mention that the vacuum line (to the MAP sensor, right?) should be attached to the right hand vacuum port on the right side of TB. Are you talking about moving to port A or B in the attached photo? 

Thanks,

-Tiago 

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<Capture7.JPG>

[Bill Van Vlack]

I'm pretty sure that the chip in the Howell is one that is programmed for the GMC. I am just guessing, but I think those chips are just tables (BINs) that define the tuning for each particular engine, so a different one would throw the tune off. But if the error codes are repeatedly  thrown with just a 'key on', then changing it out would prove/disprove your current chip.

[Johnny Bridges]

JimH, no semiconductors?  Whattaya call those things in the OEM radio>?  They ain't vacuum valves.....  :)  Your point's still valid though.

--johnny

[Tiago Soromenho]

Swapped the EPROM with the Delco one. The two MAP errors remained, and threw two more (see attached photo). Replace the original EPROM and the four errors remain... could it be that the error codes need to be reset? I thought it was done by removing power to the ECM for 10+secs (according to the Instructions in one of the documents sent or found online, but doesn’t seem to clear the error codes. Is there another way to clear the error codes?

-Tiago

202-425-5201

On Jul 12, 2020, at 12:47, Bill Van Vlack <bill.va...@gmail.com> wrote:



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[Johnny Bridges]

Did these errors appear originally at ignition turn - on, or after starting the engine?  I'm not a guru of that system, but I have to wonder if it's succumbing to electrical noise.  Farfetched, but it sounds as though ever thing else has been tested or considered.

https://groups.google.com/d/msgid/gmcmh-efi/C1DF72FE-336A-4D53-97B6-A9C6B6873C20%40gmail.com

.

[Bill Van Vlack]

The ECM receives power from both the battery and the ignition switch. Try disconnecting the battery for at least 30 seconds. 

On Sunday, July 12, 2020 at 11:32:58 AM UTC-7, Tiago Soromenho wrote:

Swapped the EPROM with the Delco one. The two MAP errors remained, and threw two more (see attached photo). Replace the original EPROM and the four errors remain... could it be that the error codes need to be reset? I thought it was done by removing power to the ECM for 10+secs (according to the Instructions in one of the documents sent or found online, but doesn’t seem to clear the error codes. Is there another way to clear the error codes?

-Tiago

202-425-5201

On Jul 12, 2020, at 12:47, Bill Van Vlack <bill.v...@gmail.com> wrote:



I'm pretty sure that the chip in the Howell is one that is programmed for the GMC. I am just guessing, but I think those chips are just tables (BINs) that define the tuning for each particular engine, so a different one would throw the tune off. But if the error codes are repeatedly  thrown with just a 'key on', then changing it out would prove/disprove your current chip.

On Sunday, July 12, 2020 at 10:28:23 AM UTC-7, Tiago Soromenho wrote:

James: Totally agreed. And the EBL system does seem to have many advantages over what I have now. Now that I’m back to going to FL and after talking to Jason Stryker from Co-op, I’ll take the coach there for evaluation, and see what Bounds says. I’m not sold on the newer sniper / FiTech FIs...

Randy/Bill: Update on that MAP sensor. I Gerry-rigged jumper wires to read the output of the MAP sensor and it outputs 4.8v with key on, engine off. Once I turn engine on (cold engine, idle mode) output is 2.8v. I can see the same readings on the ALDLdroid app, so that seems to indicate the ECM is receiving the voltage output, and relating it to the tablet. That eliminates any theory that there’s a break in the electric wires in the harness...

So that goes back to original question: why the error codes if the MAP sensor is fine, the wires are fine, and the ECM gets and passes on the voltage output.  Going to rummage through a couple ECM units Don Virta left with me to see if changing the chip (if I have another) will change anything, in case the chip is defective...

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[Tiago Soromenho]

THAT DID IT!!!!

No more error codes. All gone. I was removing the 5amp fuses in the fuse box next to ECM but obviously that doesn’t cut power to ECM. Instead of disconnecting the battery (I also have a battery disconnect switch, but have a combiner across the isolator, so removing starter battery Cables might not have cut all power to ECU...) I removed the two massive pin connectors to the back of the ECM.  Waited 20secs, plugged then back in. No codes on key on. No codes on engine on. No more engine check light from ECM either. 

Awesome! Thanks guys!!!

-Tiago

202-425-5201

On Jul 12, 2020, at 13:51, Bill Van Vlack <bill.va...@gmail.com> wrote:



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[James Hupy]

Johnny, just memory trippin' a bit, waaay back to Commodore 64 days. Cassette memory tapes, keystroke software for word processors, etc. Then came floppy discs, 32k memory capable. 

     When I was studying for my Ham license, all theory was vacuum tube and superhet or crystal. All Morse code, with a telegraph key. 

     Then came transistor theory. The pace quickened a bit. Then, integrated circuits. With a resultant jump in speed. 

     The pace of life has quickened with each technological breakthrough.  Transistor radios seem like a very long time ago, now. Analog telephone, the brick we used to call them. 

     Then came the digital revolution.  And all the personal toys that followed. Remember "pong" ?

     "Times, they are 'a changin". Don't stand still, something sinister might be gaining ground on you. Grinnin' still.

Jim Hupy

Salem, Oregon 

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[Bill Van Vlack]

Kudos!  

I had a similar thing happen..  When I wired my EFI, I assumed that all it needed was ignition power, so any BAT pin got ignition power. I was struggling with getting the IAC to control idle. When Randy pointed out that the ECM parks the IAC when ignition is turned off, I realized that SOMETHING had to be moving that IAC, went back and looked at the wiring diagram, wired in a BAT connection and all was well.

On Sunday, July 12, 2020 at 12:06:55 PM UTC-7, Tiago Soromenho wrote:

THAT DID IT!!!!

No more error codes. All gone. I was removing the 5amp fuses in the fuse box next to ECM but obviously that doesn’t cut power to ECM. Instead of disconnecting the battery (I also have a battery disconnect switch, but have a combiner across the isolator, so removing starter battery Cables might not have cut all power to ECU...) I removed the two massive pin connectors to the back of the ECM.  Waited 20secs, plugged then back in. No codes on key on. No codes on engine on. No more engine check light from ECM either. 

Awesome! Thanks guys!!!

-Tiago

202-425-5201

On Jul 12, 2020, at 13:51, Bill Van Vlack <bill.v...@gmail.com> wrote:



The ECM receives power from both the battery and the ignition switch. Try disconnecting the battery for at least 30 seconds. 

On Sunday, July 12, 2020 at 11:32:58 AM UTC-7, Tiago Soromenho wrote:

Swapped the EPROM with the Delco one. The two MAP errors remained, and threw two more (see attached photo). Replace the original EPROM and the four errors remain... could it be that the error codes need to be reset? I thought it was done by removing power to the ECM for 10+secs (according to the Instructions in one of the documents sent or found online, but doesn’t seem to clear the error codes. Is there another way to clear the error codes?

-Tiago

202-425-5201

On Jul 12, 2020, at 12:47, Bill Van Vlack <bill.v...@gmail.com> wrote:



I'm pretty sure that the chip in the Howell is one that is programmed for the GMC. I am just guessing, but I think those chips are just tables (BINs) that define the tuning for each particular engine, so a different one would throw the tune off. But if the error codes are repeatedly  thrown with just a 'key on', then changing it out would prove/disprove your current chip.

On Sunday, July 12, 2020 at 10:28:23 AM UTC-7, Tiago Soromenho wrote:

James: Totally agreed. And the EBL system does seem to have many advantages over what I have now. Now that I’m back to going to FL and after talking to Jason Stryker from Co-op, I’ll take the coach there for evaluation, and see what Bounds says. I’m not sold on the newer sniper / FiTech FIs...

Randy/Bill: Update on that MAP sensor. I Gerry-rigged jumper wires to read the output of the MAP sensor and it outputs 4.8v with key on, engine off. Once I turn engine on (cold engine, idle mode) output is 2.8v. I can see the same readings on the ALDLdroid app, so that seems to indicate the ECM is receiving the voltage output, and relating it to the tablet. That eliminates any theory that there’s a break in the electric wires in the harness...

So that goes back to original question: why the error codes if the MAP sensor is fine, the wires are fine, and the ECM gets and passes on the voltage output.  Going to rummage through a couple ECM units Don Virta left with me to see if changing the chip (if I have another) will change anything, in case the chip is defective...

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[Tiago Soromenho]

Yes. Always something silly— wether debugging software code or engines...

We’ll see if the low MPG continues when I go down to FL. Right now all seems fine. No oil leaks, belts look fine, engine runs, no EFI error codes... Longest trip taken on this coach (with me as owner) has been ~400 miles from Austin to Oklahoma. Going to undertake about 3x that in a few days. Let’s see how it goes! 🤞🏼

-Tiago

202-425-5201

On Jul 12, 2020, at 14:30, Bill Van Vlack <bill.va...@gmail.com> wrote:



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[Bill Van Vlack]

What's 'low'?  Also, once the ECM is reset it loses its learned tables and has to start over, so it may start out sluggish and then improve over a day or so. Good luck on the trip!

Now to start working on the EBL system. You have to send RBob (DynamicEFI) an ECM to modify or let him provide one for $50.00. I understand that the 1227727 is the same as 1227747 except in a weatherproof case. And there are some on Ebay for $30.00. For 20 bucks, I'd let RBob supply it.

On Sunday, July 12, 2020 at 12:50:44 PM UTC-7, Tiago Soromenho wrote:

Yes. Always something silly— wether debugging software code or engines...

We’ll see if the low MPG continues when I go down to FL. Right now all seems fine. No oil leaks, belts look fine, engine runs, no EFI error codes... Longest trip taken on this coach (with me as owner) has been ~400 miles from Austin to Oklahoma. Going to undertake about 3x that in a few days. Let’s see how it goes! 🤞🏼

-Tiago

202-425-5201

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[Johnny Bridges]

The thread is drifting, but Commodore 64 users were newbies.  We of the Truly Suave had a Commpdore Personal Electronic Transactor (PET) with a builtin monitor and datasette.  Cost me 700 bucks.  I used a 64 to drive the transmitter remote display in the Atlanta studios, including a little routine to correct the bassackwards case in the 64 ASCII.

Hpowever, what I need now is a method of turning the data from the MSD Atomic FI on my coach to something that can be displayed on a laptop instead of the little handheld monitor/controller.  Does anyone know if something like this exists?  I've email in to Holley/MSD support, ain't hearn back yet.

--johnny

When I sat my FCC license exams, Element three was all tube.

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/CALxoeyvbKFJF4rTTTSRA6j5YX3NcHOzHqJck5nt_HJ7hEijRvQ%40mail.gmail.com.

[Bill Van Vlack]

I found this program which, if you can connect a serial signal, will draw any gauge you can imagine. If you are good with Visual Studio and coding, you can write a driver to do the connection. Randy and I worked with the developer of the program to make one for the EBL system. If you can find out what the serial stream is, then that is a possibility. He charges $200.00 to write the driver, or you can use the info he provides to allow you write your own. 

The WinLog program, and its companion WinLogView is extremely robust and customizable. WinLogView takes a csv datalog file and displays it on a graph. You can scale the parameters and ranges to duplicate a multi-trace recorder - i.e, every parameter has its own horizontal slot on the screen. It is also free, or $30.00 if you want to avoid the startup countdown.

I would be surprised if Holley would reveal the protocol, but maybe you can reverse engineer it. For the EBL, BobR gave us the word length and offset for each parameter we were interested in and the developer created a mask that parsed them into C++ code variables.

On Sunday, July 12, 2020 at 1:34:05 PM UTC-7, Johnny Bridges wrote:

The thread is drifting, but Commodore 64 users were newbies.  We of the Truly Suave had a Commpdore Personal Electronic Transactor (PET) with a builtin monitor and datasette.  Cost me 700 bucks.  I used a 64 to drive the transmitter remote display in the Atlanta studios, including a little routine to correct the bassackwards case in the 64 ASCII.

Hpowever, what I need now is a method of turning the data from the MSD Atomic FI on my coach to something that can be displayed on a laptop instead of the little handheld monitor/controller.  Does anyone know if something like this exists?  I've email in to Holley/MSD support, ain't hearn back yet.

--johnny

When I sat my FCC license exams, Element three was all tube.

On Sunday, July 12, 2020, 3:31:18 PM EDT, James Hupy <james...@gmail.com> wrote:

Johnny, just memory trippin' a bit, waaay back to Commodore 64 days. Cassette memory tapes, keystroke software for word processors, etc. Then came floppy discs, 32k memory capable. 

     When I was studying for my Ham license, all theory was vacuum tube and superhet or crystal. All Morse code, with a telegraph key. 

     Then came transistor theory. The pace quickened a bit. Then, integrated circuits. With a resultant jump in speed. 

     The pace of life has quickened with each technological breakthrough.  Transistor radios seem like a very long time ago, now. Analog telephone, the brick we used to call them. 

     Then came the digital revolution.  And all the personal toys that followed. Remember "pong" ?

     "Times, they are 'a changin". Don't stand still, something sinister might be gaining ground on you. Grinnin' still.

Jim Hupy

Salem, Oregon 

On Sun, Jul 12, 2020, 11:51 AM Bill Van Vlack <bill.v...@gmail.com> wrote:

The ECM receives power from both the battery and the ignition switch. Try disconnecting the battery for at least 30 seconds. 

On Sunday, July 12, 2020 at 11:32:58 AM UTC-7, Tiago Soromenho wrote:

Swapped the EPROM with the Delco one. The two MAP errors remained, and threw two more (see attached photo). Replace the original EPROM and the four errors remain... could it be that the error codes need to be reset? I thought it was done by removing power to the ECM for 10+secs (according to the Instructions in one of the documents sent or found online, but doesn’t seem to clear the error codes. Is there another way to clear the error codes?

-Tiago

202-425-5201

On Jul 12, 2020, at 12:47, Bill Van Vlack <bill.v...@gmail.com> wrote:



I'm pretty sure that the chip in the Howell is one that is programmed for the GMC. I am just guessing, but I think those chips are just tables (BINs) that define the tuning for each particular engine, so a different one would throw the tune off. But if the error codes are repeatedly  thrown with just a 'key on', then changing it out would prove/disprove your current chip.

On Sunday, July 12, 2020 at 10:28:23 AM UTC-7, Tiago Soromenho wrote:

James: Totally agreed. And the EBL system does seem to have many advantages over what I have now. Now that I’m back to going to FL and after talking to Jason Stryker from Co-op, I’ll take the coach there for evaluation, and see what Bounds says. I’m not sold on the newer sniper / FiTech FIs...

Randy/Bill: Update on that MAP sensor. I Gerry-rigged jumper wires to read the output of the MAP sensor and it outputs 4.8v with key on, engine off. Once I turn engine on (cold engine, idle mode) output is 2.8v. I can see the same readings on the ALDLdroid app, so that seems to indicate the ECM is receiving the voltage output, and relating it to the tablet. That eliminates any theory that there’s a break in the electric wires in the harness...

So that goes back to original question: why the error codes if the MAP sensor is fine, the wires are fine, and the ECM gets and passes on the voltage output.  Going to rummage through a couple ECM units Don Virta left with me to see if changing the chip (if I have another) will change anything, in case the chip is defective...

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[Johnny Bridges]

Thanks, that's probably beyond my  neophyte's abilities.  Lessee what they have to say.  You'd think they'd offer a plugin solution for a price.  Their tech guys were most helpful in sorting out my cold start/idle problems.

--johnny

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[Bill Van Vlack]

I think they do....  See RacePak.

If they send out a serial stream and will release the protocol, and you're willing to shell out a couple hundred bucks to Justin at DevTechnics, it could happen. I'm happy to help.

On Sunday, July 12, 2020 at 2:28:52 PM UTC-7, Johnny Bridges wrote:

Thanks, that's probably beyond my  neophyte's abilities.  Lessee what they have to say.  You'd think they'd offer a plugin solution for a price.  Their tech guys were most helpful in sorting out my cold start/idle problems.

--johnny

https://groups.google.com/d/msgid/gmcmh-efi/a5495c4d-f070-48f7-a08e-8bcd73c1199ao%40googlegroups.com

.

[Johnny Bridges]

with that information I can get it done for nothing :)  Couple of buds who work for Beltway Bandits would help me out.  They'd consider it a challenge.

--johnny

https://groups.google.com/d/ msgid/gmcmh-efi/a5495c4d-f070- 48f7-a08e-8bcd73c1199ao% 40googlegroups.com

.

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[Bill Van Vlack]

OK. Good Luck.

On Sunday, July 12, 2020 at 4:57:14 PM UTC-7, Johnny Bridges wrote:

with that information I can get it done for nothing :)  Couple of buds who work for Beltway Bandits would help me out.  They'd consider it a challenge.

--johnny

https://groups.google.com/d/msgid/gmcmh-efi/49441975-9b8d-49fb-9296-01c96201e6c0o%40googlegroups.com

.

[Bill Van Vlack]

I think the MSD Atomic TBI uses the CAN bus protocol to connect to its programmer.

[Tiago Soromenho]

Any of the FI systems should have an ALDL, OBD1 or OBD2 data port. From there you can find an adapter that can send the port data to a USB, Bluetooth or old Serial cable. Then it’s just a question of finding the right software for the device type you want To connect. I tried first with an old Windows laptop but that felt unwieldy. So I got an old Android tablet. Similar screen real estate, touch screen, and much flatter form factor. There are plenty of such display/dashboard softwares for Windows, Android, and iOS (no iOS for ALDL though)

On Jul 12, 2020, at 15:34, 'Johnny Bridges' via GMCMH EFI <gmcm...@googlegroups.com> wrote:



To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/1696927803.358055.1594586041770%40mail.yahoo.com.

[Johnny Bridges]

Thanks! 

--johnny

https://groups.google.com/d/ msgid/gmcmh-efi/49441975-9b8d- 49fb-9296-01c96201e6c0o% 40googlegroups.com

.

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[Bill Van Vlack]

I think Atomic, Holley Sniper, and FiTech have a single data port with a proprietary protocol that connects the throttle body ECU to  their hand-held programmer. For the Atomic, at least, I was unable to find a cable and/or module that delivers an ODB2 stream. Both AEM and Dakota DIgital provide products that connect the Atomic to their proprietary gauge and datalog products, but not to ODB2. You or Johnny may have more luck finding adapters, etc. that would do that. Let me know if you do.

On Sunday, July 12, 2020 at 8:04:47 PM UTC-7, Tiago Soromenho wrote:

Any of the FI systems should have an ALDL, OBD1 or OBD2 data port. From there you can find an adapter that can send the port data to a USB, Bluetooth or old Serial cable. Then it’s just a question of finding the right software for the device type you want To connect. I tried first with an old Windows laptop but that felt unwieldy. So I got an old Android tablet. Similar screen real estate, touch screen, and much flatter form factor. There are plenty of such display/dashboard softwares for Windows, Android, and iOS (no iOS for ALDL though)

On Jul 12, 2020, at 15:34, 'Johnny Bridges' via GMCMH EFI <gmcm...@googlegroups.com> wrote:



The thread is drifting, but Commodore 64 users were newbies.  We of the Truly Suave had a Commpdore Personal Electronic Transactor (PET) with a builtin monitor and datasette.  Cost me 700 bucks.  I used a 64 to drive the transmitter remote display in the Atlanta studios, including a little routine to correct the bassackwards case in the 64 ASCII.

Hpowever, what I need now is a method of turning the data from the MSD Atomic FI on my coach to something that can be displayed on a laptop instead of the little handheld monitor/controller.  Does anyone know if something like this exists?  I've email in to Holley/MSD support, ain't hearn back yet.

--johnny

When I sat my FCC license exams, Element three was all tube.

On Sunday, July 12, 2020, 3:31:18 PM EDT, James Hupy <james...@gmail.com> wrote:

Johnny, just memory trippin' a bit, waaay back to Commodore 64 days. Cassette memory tapes, keystroke software for word processors, etc. Then came floppy discs, 32k memory capable. 

     When I was studying for my Ham license, all theory was vacuum tube and superhet or crystal. All Morse code, with a telegraph key. 

     Then came transistor theory. The pace quickened a bit. Then, integrated circuits. With a resultant jump in speed. 

     The pace of life has quickened with each technological breakthrough.  Transistor radios seem like a very long time ago, now. Analog telephone, the brick we used to call them. 

     Then came the digital revolution.  And all the personal toys that followed. Remember "pong" ?

     "Times, they are 'a changin". Don't stand still, something sinister might be gaining ground on you. Grinnin' still.

Jim Hupy

Salem, Oregon 

On Sun, Jul 12, 2020, 11:51 AM Bill Van Vlack <bill.v...@gmail.com> wrote:

The ECM receives power from both the battery and the ignition switch. Try disconnecting the battery for at least 30 seconds. 

On Sunday, July 12, 2020 at 11:32:58 AM UTC-7, Tiago Soromenho wrote:

Swapped the EPROM with the Delco one. The two MAP errors remained, and threw two more (see attached photo). Replace the original EPROM and the four errors remain... could it be that the error codes need to be reset? I thought it was done by removing power to the ECM for 10+secs (according to the Instructions in one of the documents sent or found online, but doesn’t seem to clear the error codes. Is there another way to clear the error codes?

-Tiago

202-425-5201

On Jul 12, 2020, at 12:47, Bill Van Vlack <bill.v...@gmail.com> wrote:



I'm pretty sure that the chip in the Howell is one that is programmed for the GMC. I am just guessing, but I think those chips are just tables (BINs) that define the tuning for each particular engine, so a different one would throw the tune off. But if the error codes are repeatedly  thrown with just a 'key on', then changing it out would prove/disprove your current chip.

On Sunday, July 12, 2020 at 10:28:23 AM UTC-7, Tiago Soromenho wrote:

James: Totally agreed. And the EBL system does seem to have many advantages over what I have now. Now that I’m back to going to FL and after talking to Jason Stryker from Co-op, I’ll take the coach there for evaluation, and see what Bounds says. I’m not sold on the newer sniper / FiTech FIs...

Randy/Bill: Update on that MAP sensor. I Gerry-rigged jumper wires to read the output of the MAP sensor and it outputs 4.8v with key on, engine off. Once I turn engine on (cold engine, idle mode) output is 2.8v. I can see the same readings on the ALDLdroid app, so that seems to indicate the ECM is receiving the voltage output, and relating it to the tablet. That eliminates any theory that there’s a break in the electric wires in the harness...

So that goes back to original question: why the error codes if the MAP sensor is fine, the wires are fine, and the ECM gets and passes on the voltage output.  Going to rummage through a couple ECM units Don Virta left with me to see if changing the chip (if I have another) will change anything, in case the chip is defective...

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[Johnny Bridges]

The Atomic does not locate the computer in the throttle body.  It is a separate box, which has a harness connecting it to the TB and to sensors and the distributor tach outlet.  There's also another couple of connectors not used in the GMC.  From the computer box comes a connector which hooks to the hand held.  It isn't OBD 1 or 2, rather proprietary.  Mine has an extension cable, provided by Holley/Atomic.  Nothing's gonna happen in a hurry, but I'll let yall know what I end up with.

--johnny

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[Randy Van Winkle]

Tiago,

What Bill said on the correct port to use for the MAP sensor.  As far as the PROM is concerned, yes, you could try one to see if it works and is any better for your situation. However, only start and let idle because without knowing what those proms are for, you run the risk of damaging the engine if you rev it hard. If it idles well, you then could increase rpms slowly to see how it behaves. I would be surprised if you get any different results with a different prom because there is nothing in the programming on the prom that affects how error reporting is done from the sensors. You could try unplugging and replugging the connectors to the ecm in order to reseat them. One of the pins may not be seated well.

As for your probes on the MAP connector your reading are what I would expect. The one you need is with the engine running and probe the center pin.  That is harder to do as you need the connector plugged to the sensor so you need to pierce the wire (I sometimes use a straight pin to do that and then put my probe onto that). That will be the signal voltage back from the MAP - should be around 2v at idle and change as you put some load on the engine.

Randy

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[Randy Van Winkle]

Tiago,

Glad you got the errors cleared. Sorry I did not question you when you earlier said you had reset the error codes my removing power to the ECM. As Bruce indicated, you have to disconnect the battery. Hope you have an enjoyable and safe trip. Let us know if you have any other issues.

Randy

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/8FAC6AC7-AAAF-4B45-A72A-A88F7EEAB730%40gmail.com.

[Tiago Soromenho]

Hi Randy!

Thanks for the feedback and tips!

I did replace the custom EPROM with the Delco one at just idle to make sure the root codes were not due to malfunctioning EPROM. The new one added a couple more error codes, and didn’t remove the old ones... that was odd, and showed that error codes remain when I placed back the original EPROM. Turns out I had to completely disconnect the ECM for that to happen. All error codes are cleared now, and haven’t come back. 

As to monitoring the output from any of the sensors, what I ended up doing is using spare wires to connect the load and ground pins, and using a third one clipped to the probe to read output voltage from the sensor (see attached photo) — much less problematic than striping a wire to permanently expose the copper... 

Cheers!

-Tiago

202-425-5201

On Jul 13, 2020, at 19:11, Randy Van Winkle <rlva...@gmail.com> wrote:



Tiago,

What Bill said on the correct port to use for the MAP sensor.  As far as the PROM is concerned, yes, you could try one to see if it works and is any better for your situation. However, only start and let idle because without knowing what those proms are for, you run the risk of damaging the engine if you rev it hard. If it idles well, you then could increase rpms slowly to see how it behaves. I would be surprised if you get any different results with a different prom because there is nothing in the programming on the prom that affects how error reporting is done from the sensors. You could try unplugging and replugging the connectors to the ecm in order to reseat them. One of the pins may not be seated well.

As for your probes on the MAP connector your reading are what I would expect. The one you need is with the engine running and probe the center pin.  That is harder to do as you need the connector plugged to the sensor so you need to pierce the wire (I sometimes use a straight pin to do that and then put my probe onto that). That will be the signal voltage back from the MAP - should be around 2v at idle and change as you put some load on the engine.

Randy

On Sun, Jul 12, 2020 at 12:45 PM Tiago Soromenho <tiago.s...@gmail.com> wrote:

I do see your attached photo. I’ll move the line (if it reaches. They didn't leave much extra length to play with...)

Also I have two extra PROMs. The one I have on right now (see photo) seems to be a custom made one?  The other two should still work? One says “Delco ARJT 7489” and the other “ANLW 5489” 

Would it hurt anything to swap the custom one to the Delco one, for example, just to check if that gets rid of error codes? 

<image5.jpeg>

<image6.jpeg>

<image7.jpeg>

-Tiago

202-425-5201

On Jul 12, 2020, at 12:36, Bill Van Vlack <bill.va...@gmail.com> wrote:



I don't know why the photo won't display. I've attached it as a file... maybe that will work.

On Sunday, July 12, 2020 at 10:33:33 AM UTC-7, Bill Van Vlack wrote:

Move it to port A (passenger side) in your photo below. Port B is ported vacuum (center vacuum port on front of TB). The port on the driver's side is also manifold vacuum.

Here is a photo. Either manifold vacuum will work, but in your case the 'right' one in this photo is already used.

On Sunday, July 12, 2020 at 9:28:52 AM UTC-7, Tiago Soromenho wrote:

Hi Randy,

When you mention that the vacuum line (to the MAP sensor, right?) should be attached to the right hand vacuum port on the right side of TB. Are you talking about moving to port A or B in the attached photo? 

Thanks,

-Tiago 

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[Tiago Soromenho]

Low MPG is in the 5-6mpg range. That’s what started this whole “let me check my systems see if there’s anything off kilter”...

The O2 sensor was definitely bad. Don’t thing the MAP was. I did change the MAP port to the one in front as you suggested. Now no error codes. Let’s see what the mileage turn out to be on this TX to FL trip...!

-Tiago

202-425-5201

On Jul 12, 2020, at 15:12, Bill Van Vlack <bill.va...@gmail.com> wrote:



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[Bill Van Vlack]

If the O2 thought it was lean, the ECM logic would try to add fuel in closed loop mode, which it's in most of the time. How did you determine it was bad?

On Tuesday, July 14, 2020 at 1:55:22 PM UTC-7, Tiago Soromenho wrote:

Low MPG is in the 5-6mpg range. That’s what started this whole “let me check my systems see if there’s anything off kilter”...

The O2 sensor was definitely bad. Don’t thing the MAP was. I did change the MAP port to the one in front as you suggested. Now no error codes. Let’s see what the mileage turn out to be on this TX to FL trip...!

-Tiago

202-425-5201

To view this discussion on the web visit https://groups.google.com/d/msgid/gmcmh-efi/998de56c-ad61-4e5b-86b8-874aced2abbco%40googlegroups.com.

[Tiago Soromenho]

I determined it was "bad" mainly because after I swapped it with a new one, the error codes on the ALDL data feed (ie, on ALDLdroid) cleared.  I did keep the previous one, just in case...

-Tiago
202-425-5201

Bill Van Vlack

July 14, 2020 at 16h15

If the O2 thought it was lean, the ECM logic would try to add fuel in closed loop mode, which it's in most of the time. How did you determine it was bad?

On Tuesday, July 14, 2020 at 1:55:22 PM UTC-7, Tiago Soromenho wrote:

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Tiago Soromenho

July 12, 2020 at 21h57

[Bill Van Vlack]

Hi Johnny....

  Do you have the current MSD/Atomic/Holley throttle body? This page says that the ECU is in the throttle body, and this page  shows a picture of it...  It's mounted on the passenger side of the throttle body and has all of the sensor connections.

If so, I've done a little looking around, and find that the ECU talks to the hand-held and some Racepac, AEM, and Dakota Digital devices using some version of the CAN protocol which can be found here, page 88.

I think there was an earlier MSD/Atomic (pre-Holley). Perhaps that is what you have.

On Monday, July 13, 2020 at 1:51:16 PM UTC-7, Johnny Bridges wrote:

The Atomic does not locate the computer in the throttle body.  It is a separate box, which has a harness connecting it to the TB and to sensors and the distributor tach outlet.  There's also another couple of connectors not used in the GMC.  From the computer box comes a connector which hooks to the hand held.  It isn't OBD 1 or 2, rather proprietary.  Mine has an extension cable, provided by Holley/Atomic.  Nothing's gonna happen in a hurry, but I'll let yall know what I end up with.

--johnny

https://groups.google.com/d/msgid/gmcmh-efi/9abb78c8-7975-42b2-82ed-7b4e2918dcd7o%40googlegroups.com

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[Johnny Bridges]

No.  Separate box, although it might be just a connection box.  I'll look further.

--johnny

https://groups.google.com/d/ msgid/gmcmh-efi/9abb78c8-7975- 42b2-82ed-7b4e2918dcd7o% 40googlegroups.com

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[Johnny Bridges]

It is called the Power Module.  The installation manual refers to the CAN going to the hand held controller, so I suspect it s in fact CANbus.  Pressure is low, I will treat the line to a pair of new filters.  If it remains low, new pump.  It runs in full mode rather than pulsed, with an external regulator and return line.  It was sagging a bit on throttle opening both filters and pump are suspect.  It was holding the required 48 PSI, but dropped into the 30s.

--johnny

https://groups.google.com/d/msgid/gmcmh-efi/896172741.1805678.1594901882142%40mail.yahoo.com

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[Bill Van Vlack]

The ECU for the Holley/Atomic/MSD is in the Throttle Body.  Here is a link to it as a replacement part. On that page is a link to a PDF for installation instructions, and here is a picture of it. It is located on the passenger side.

On Thursday, July 16, 2020 at 10:58:20 AM UTC-7, Johnny Bridges wrote:

It is called the Power Module.  The installation manual refers to the CAN going to the hand held controller, so I suspect it s in fact CANbus.  Pressure is low, I will treat the line to a pair of new filters.  If it remains low, new pump.  It runs in full mode rather than pulsed, with an external regulator and return line.  It was sagging a bit on throttle opening both filters and pump are suspect.  It was holding the required 48 PSI, but dropped into the 30s.

--johnny

On Thursday, July 16, 2020, 8:18:09 AM EDT, 'Johnny Bridges' via GMCMH EFI <gmcm...@googlegroups.com> wrote:

No.  Separate box, although it might be just a connection box.  I'll look further.

--johnny

https://groups.google.com/d/msgid/gmcmh-efi/3c1cca53-7a92-48f5-817a-0654d3e17bfdo%40googlegroups.com

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[Johnny Bridges]

As it turns out, this'n is a 2910 throttle body, 2920 pump and 2922 (if I got all the numbers tright) return kit and external regulator.  It appears to be pre - Holley.  Interestingly, the installation directions say specifically that it is not CARB approved.  I suspect that approval came after Holley bought it, and I suspect production will continue as long as it's the only CARB approved system they sell.

Anyway, thew Power Module connects to the throttle body and the hand held controller via a six pin CANbus.  The handheld has a place for a removable memory and a small USB connector.  This leads me to believe there's a monitor setup, out there somewhere, no need to reinvent the wheel.

--johnny

https://groups.google.com/d/ msgid/gmcmh-efi/3c1cca53-7a92- 48f5-817a-0654d3e17bfdo% 40googlegroups.com

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