X11 diagnostic port readings
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Bing
Nov 21, 2012, 7:27:04 PM11/21/12
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Hi Folks!
I was recommended by Dan to this group. I was actually quite surprised to see his reply when I sent him an email with questions about the mixture adjustment page he had put up years ago.
I purchased my first Mercedes back in June. It's a 92 190e 2.6. It's no v8 coupe but it is a clean 1 owner car, great for commuting. It needed a heater core at the time (which was why the PO gave up on it), so i replaced it and put it back on the road. I wasn't able to get it to pass emissions (failed with high NOx). So I did a bunch of maintenance items: o2 sensor, cts, fuel filter, thermostat, plugs, fluids. But really over all the car looked pretty well looked after. It already had a new cat/exhaust, and new ignition parts.
It got much closer, with NOx only 10% over the limit (all the while with below average HC and WAY below average CO), but still failed.
So I started to do some reading, and got to Dan's page.
During the static duty cycle testing, right off the bat it's reading 8v between pin 2 and 3 at the X11 port, with ignition on engine off, which is around 33%, instead of the 70% spec (according to 190e service manual as well).
If I open up the throttle, the reading would increase to 10.5, and drop back down to 9.33 at WOT. However when i deflect the air flow plate with ignition on, engine off, the duty cycle does not change at all.
So Far:
- The airflow meter tests fine, with smooth rise of voltage to 5v, all within spec.
- The connection between the AFM and the ECU is also good
- The throttle valve switch is also good, both at idle and full contact
- The connection between the throttle valve switch and ECU is also good
Other symptoms:
When I open up the throttle, there is no momentary enrichment, it actually will leans out.
With the engine warm and idling, my duty cycle is around 8v or 30% (rich). However when i rev the engine to 2500rpm, it drops down to 50%.
If i adjust the duty cycle to 50% at idling, when i rev up the engine to 2500, the duty cycle will lean out to 60%. And if i rev it hard, the duty cycle will lean out to over 90% briefly! I can only imagine this is worse when it's under load
My emissions report also reflect this. The NOx readings spike everytime the car accelerates during the IM240 test.
So I think for now I might enrich the EHA Adjustment to get more fuel on acceleration, just to get it through emissions (I only have about 10 days left before final expiration). But I'd like to figure out what's causing this issue!
What would you suggest I do next?
Thanks for any suggestions and sorry about the long post!
I was recommended by Dan to this group. I was actually quite surprised to see his reply when I sent him an email with questions about the mixture adjustment page he had put up years ago.
I purchased my first Mercedes back in June. It's a 92 190e 2.6. It's no v8 coupe but it is a clean 1 owner car, great for commuting. It needed a heater core at the time (which was why the PO gave up on it), so i replaced it and put it back on the road. I wasn't able to get it to pass emissions (failed with high NOx). So I did a bunch of maintenance items: o2 sensor, cts, fuel filter, thermostat, plugs, fluids. But really over all the car looked pretty well looked after. It already had a new cat/exhaust, and new ignition parts.
It got much closer, with NOx only 10% over the limit (all the while with below average HC and WAY below average CO), but still failed.
So I started to do some reading, and got to Dan's page.
During the static duty cycle testing, right off the bat it's reading 8v between pin 2 and 3 at the X11 port, with ignition on engine off, which is around 33%, instead of the 70% spec (according to 190e service manual as well).
If I open up the throttle, the reading would increase to 10.5, and drop back down to 9.33 at WOT. However when i deflect the air flow plate with ignition on, engine off, the duty cycle does not change at all.
So Far:
- The airflow meter tests fine, with smooth rise of voltage to 5v, all within spec.
- The connection between the AFM and the ECU is also good
- The throttle valve switch is also good, both at idle and full contact
- The connection between the throttle valve switch and ECU is also good
Other symptoms:
When I open up the throttle, there is no momentary enrichment, it actually will leans out.
With the engine warm and idling, my duty cycle is around 8v or 30% (rich). However when i rev the engine to 2500rpm, it drops down to 50%.
If i adjust the duty cycle to 50% at idling, when i rev up the engine to 2500, the duty cycle will lean out to 60%. And if i rev it hard, the duty cycle will lean out to over 90% briefly! I can only imagine this is worse when it's under load
My emissions report also reflect this. The NOx readings spike everytime the car accelerates during the IM240 test.
So I think for now I might enrich the EHA Adjustment to get more fuel on acceleration, just to get it through emissions (I only have about 10 days left before final expiration). But I'd like to figure out what's causing this issue!
What would you suggest I do next?
Thanks for any suggestions and sorry about the long post!
Bing
Nov 21, 2012, 7:31:10 PM11/21/12
to mbco...@googlegroups.com
Oh just to tell you guys a bit more about me. I live in Surrey, BC (Canada). I first got into domestic cars when I was younger, and then tried out an E30, really enjoyed it. And that's what got me into German cars.
Right now I have this 190e, an e30 325ic, an e30 SETA with i head, and an 85 Camaro with a 355TPI.
Right now I have this 190e, an e30 325ic, an e30 SETA with i head, and an 85 Camaro with a 355TPI.
Dick Spellman
Nov 22, 2012, 2:52:58 PM11/22/12
to mbco...@googlegroups.com
Hello Bing,
Here are a few notes that may help you arrive at a similar duty cycle
reading (idle/2500rpm). I use a series connector on one leg of the EHA
electrical connector to the EHA to see if current is floating right
around 0 ma (+/- 3ma) while also reading the O2 sensor voltage and
adjusting duty cycle. I have included a write-up by Charlie Wagner that
covers the desired readings on 116/117 V-8's written back in 2005. It
may prove useful in tuning your 190e 2.6 in-line 6 cylinder. I have
used this successfully on my 300se's, slc and sec.
As for the EHA adjustment that Stu Ritter speaks of in the Mercedes
Bible (publisher Bentley); yes you can make very small incremental
adjustments on the 'screw' hidden behind the slotted back cover on the
EHA to arrive at a differential pressure of 0.45 bar. Factory is 0.40
bar. You will need a set of gauges connected to both upper and lower
fuel distributor chambers to do this accurately. If you need a copy of
a photo/note write-up on gauges hooked-up to the fuel distributor drop
me a note and I will post the pdf that I created a few years ago.
I use a $20 Sears multimeter with 'duty cycle' to adjust the lambda. I
just purchased this second meter when the first died after 11 years use.
It's inexpensive and makes for an easy review of lambda without the
math involved in vdc readings.
Here's Charlie's write-up:
> I recently had the pleasure of figuring out how to check and
> adjust the KE Jetronic fuel injection system (on a 1991 420sel) with
> simple shop tools. I thought I would post a summary of what is required
> in case anyone else has a similar project. In my case, the PO had
> adjusted the mixture lean in order to "solve" a high idle problem. The
> ultimate solution was to re-set the mixture correctly and also replace
> the idle air valve.
> 1. Get the factory manual and read the sections on the fuel
> injection system. However, the essential knowledge on what to check is
> obfuscated by lots of diagnostic procedures for things very unlikely to
> be wrong, like bad wiring. The information on how to test the throttle
> position switch, the idle air valve, the 2 temp senders, and the EHA
> valve resistance, is all in there, and the basic tests can all be done
> with a simple DVOM.
> 2. Read 2 articles. One by Steve Brotherton, called
> Mercedes-Benz Drivability: evaluating electronic engine controls
> (available on the internet on the Continental Imports web site). The
> other called Bosch KE3-Jetronic Mixture Adjustment, available on the net
> atwww.landiss.com/mixture.htm.
> 3. The basic revelation is that the "on-off ratio" can be
> measured on diagnostic connector X-11 with a simple voltmeter. Pin 2 is
> ground, and pin 3 is the on-off ratio signal (the pins are numbered on
> the connector). An analog voltmeter works best, because you can "see"
> the on-off ratio changing, but a DVOM will work fine too. The on-off
> ratio is equal to 1 minus the voltage (measured between pins 2 and 3),
> divided by the full voltage (between pins 2 and 6, but around 14 volts),
> expressed as a percentage. So 4 volts is 1 minus 4/14, or about 70%.
> 4. Once the engine is warmed up and the injection system is
> working in closed loop, you can also measure the current going through
> the EHA valve. I made up a simple harness with some wire and connectors
> from Radio Shack that were the same size as the pins on the EHA. (The
> DVOM must be connected in series in the EHA circuit, and set to measure
> amps.) Turn on the ignition, and check that the current through the EHA
> valve is +70 MA. If the DVOM says negative current, switch the leads at
> the DVOM. Then start the engine, and watch the system adjust the
> mixture at the EHA. The idea is to adjust the mixture so that the EHA
> current ranges around 0. When it is just right, you can see the on-off
> ratio ranging around 50% (i.e., between slightly rich and slightly
> lean), and the EHA current producing those swings (when the EHA current
> is slightly positive, it is enriching a lean mixture, and when the
> current is slightly negative, it is leaning out a rich mixture). Tests
> are at 2500 rpm and at idle, and the manual tells you how close the idle
> and 2500 readings should be. Big differences probably indicate air
> leaks in the intake system somewhere.
> I hope the foregoing is helpful to someone, sometime. It was
> fun figuring it out, but would have been a lot faster with the above
> information at the beginning. Charles Wagner, 1991 420sel, 119Kmi
> --
> You are subscribed to the Google Groups "MBCoupes" group
> To post to this group send email to mbco...@googlegroups.com
> To unsubscribe send to mbcoupes+u...@googlegroups.com
> For more options visit http://groups.google.com/group/mbcoupes
Good luck on the emissions and tuning effort.
Dick Spellman
Boston, MA area
--
The information contained in this e-mail and the attachments, if any, is
legally privileged and CONFIDENTIAL. It is intended solely for the use
of the individual or entity to whom it is addressed and others
authorized to receive it. If you are not the intended recipient you are
hereby notified that any disclosure, copying, distribution, or taking
action in reliance of the contents of this information is strictly
prohibited and may be unlawful
Here are a few notes that may help you arrive at a similar duty cycle
reading (idle/2500rpm). I use a series connector on one leg of the EHA
electrical connector to the EHA to see if current is floating right
around 0 ma (+/- 3ma) while also reading the O2 sensor voltage and
adjusting duty cycle. I have included a write-up by Charlie Wagner that
covers the desired readings on 116/117 V-8's written back in 2005. It
may prove useful in tuning your 190e 2.6 in-line 6 cylinder. I have
used this successfully on my 300se's, slc and sec.
As for the EHA adjustment that Stu Ritter speaks of in the Mercedes
Bible (publisher Bentley); yes you can make very small incremental
adjustments on the 'screw' hidden behind the slotted back cover on the
EHA to arrive at a differential pressure of 0.45 bar. Factory is 0.40
bar. You will need a set of gauges connected to both upper and lower
fuel distributor chambers to do this accurately. If you need a copy of
a photo/note write-up on gauges hooked-up to the fuel distributor drop
me a note and I will post the pdf that I created a few years ago.
I use a $20 Sears multimeter with 'duty cycle' to adjust the lambda. I
just purchased this second meter when the first died after 11 years use.
It's inexpensive and makes for an easy review of lambda without the
math involved in vdc readings.
Here's Charlie's write-up:
> I recently had the pleasure of figuring out how to check and
> adjust the KE Jetronic fuel injection system (on a 1991 420sel) with
> simple shop tools. I thought I would post a summary of what is required
> in case anyone else has a similar project. In my case, the PO had
> adjusted the mixture lean in order to "solve" a high idle problem. The
> ultimate solution was to re-set the mixture correctly and also replace
> the idle air valve.
> 1. Get the factory manual and read the sections on the fuel
> injection system. However, the essential knowledge on what to check is
> obfuscated by lots of diagnostic procedures for things very unlikely to
> be wrong, like bad wiring. The information on how to test the throttle
> position switch, the idle air valve, the 2 temp senders, and the EHA
> valve resistance, is all in there, and the basic tests can all be done
> with a simple DVOM.
> 2. Read 2 articles. One by Steve Brotherton, called
> Mercedes-Benz Drivability: evaluating electronic engine controls
> (available on the internet on the Continental Imports web site). The
> other called Bosch KE3-Jetronic Mixture Adjustment, available on the net
> atwww.landiss.com/mixture.htm.
> 3. The basic revelation is that the "on-off ratio" can be
> measured on diagnostic connector X-11 with a simple voltmeter. Pin 2 is
> ground, and pin 3 is the on-off ratio signal (the pins are numbered on
> the connector). An analog voltmeter works best, because you can "see"
> the on-off ratio changing, but a DVOM will work fine too. The on-off
> ratio is equal to 1 minus the voltage (measured between pins 2 and 3),
> divided by the full voltage (between pins 2 and 6, but around 14 volts),
> expressed as a percentage. So 4 volts is 1 minus 4/14, or about 70%.
> 4. Once the engine is warmed up and the injection system is
> working in closed loop, you can also measure the current going through
> the EHA valve. I made up a simple harness with some wire and connectors
> from Radio Shack that were the same size as the pins on the EHA. (The
> DVOM must be connected in series in the EHA circuit, and set to measure
> amps.) Turn on the ignition, and check that the current through the EHA
> valve is +70 MA. If the DVOM says negative current, switch the leads at
> the DVOM. Then start the engine, and watch the system adjust the
> mixture at the EHA. The idea is to adjust the mixture so that the EHA
> current ranges around 0. When it is just right, you can see the on-off
> ratio ranging around 50% (i.e., between slightly rich and slightly
> lean), and the EHA current producing those swings (when the EHA current
> is slightly positive, it is enriching a lean mixture, and when the
> current is slightly negative, it is leaning out a rich mixture). Tests
> are at 2500 rpm and at idle, and the manual tells you how close the idle
> and 2500 readings should be. Big differences probably indicate air
> leaks in the intake system somewhere.
> I hope the foregoing is helpful to someone, sometime. It was
> fun figuring it out, but would have been a lot faster with the above
> information at the beginning. Charles Wagner, 1991 420sel, 119Kmi
> You are subscribed to the Google Groups "MBCoupes" group
> To post to this group send email to mbco...@googlegroups.com
> To unsubscribe send to mbcoupes+u...@googlegroups.com
> For more options visit http://groups.google.com/group/mbcoupes
Good luck on the emissions and tuning effort.
Dick Spellman
Boston, MA area
--
The information contained in this e-mail and the attachments, if any, is
legally privileged and CONFIDENTIAL. It is intended solely for the use
of the individual or entity to whom it is addressed and others
authorized to receive it. If you are not the intended recipient you are
hereby notified that any disclosure, copying, distribution, or taking
action in reliance of the contents of this information is strictly
prohibited and may be unlawful
Bing
Nov 23, 2012, 12:55:17 PM11/23/12
to mbco...@googlegroups.com
Hi Dick,
Thanks for your reply. I read through the brotherton article you mentioned (already read the one on Dan's page before), and it has great info, and lends much insight into how the CIS-E works. I think I can definitely get it to pass with EHA adjustment, even if I can't figure out what's actually wrong for now.
There's been an interesting development!
I tested it again after a long drive, and the static voltage is at 6v when it's hot! And when I deflect the AFM, it is actually changing the duty cycle, however only to 7v, instead of the 10v or so on the spec.
I've done tests after 15min of idling, but I guess that wasn't hot enough.
So I guess in a way it's gotten "closer". However I'm even more confused on what's causing it to be wrong. And there was no mention of doing the static testing with the engine at full operating temp in any of the guides i've read... not even in the service manual.
I think I should test my CTS readings to see if it's significantly off. Are there any other temp sensors that the ECU take info from?
Thanks for your reply. I read through the brotherton article you mentioned (already read the one on Dan's page before), and it has great info, and lends much insight into how the CIS-E works. I think I can definitely get it to pass with EHA adjustment, even if I can't figure out what's actually wrong for now.
There's been an interesting development!
I tested it again after a long drive, and the static voltage is at 6v when it's hot! And when I deflect the AFM, it is actually changing the duty cycle, however only to 7v, instead of the 10v or so on the spec.
I've done tests after 15min of idling, but I guess that wasn't hot enough.
So I guess in a way it's gotten "closer". However I'm even more confused on what's causing it to be wrong. And there was no mention of doing the static testing with the engine at full operating temp in any of the guides i've read... not even in the service manual.
I think I should test my CTS readings to see if it's significantly off. Are there any other temp sensors that the ECU take info from?
Bing
Nov 27, 2012, 4:13:26 PM11/27/12
to mbco...@googlegroups.com
Hi,
I ended up richening the EHA adjustment to pass emissions. Still not exactly sure why it was off in the first place, but i guess this will do for now.
I didn't want to make a harness to test the EHA current, so I just adjusted it slightly while monitoring the x11 duty read out. I richened the EHA and leaned out the fuel mixture adjustment, to reach 50% duty at idle, 45% at 2500rpm, and 40% underload while driving. I figure this is pretty close to spec. I will check the duty cycle from time to time to make sure everything is still good.
Thank you all for the help!
I'll check back from time to time to see if there's anything i could lend any insight to :)
I ended up richening the EHA adjustment to pass emissions. Still not exactly sure why it was off in the first place, but i guess this will do for now.
I didn't want to make a harness to test the EHA current, so I just adjusted it slightly while monitoring the x11 duty read out. I richened the EHA and leaned out the fuel mixture adjustment, to reach 50% duty at idle, 45% at 2500rpm, and 40% underload while driving. I figure this is pretty close to spec. I will check the duty cycle from time to time to make sure everything is still good.
Thank you all for the help!
I'll check back from time to time to see if there's anything i could lend any insight to :)
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