Tn-signal at Engine control module - PeachParts Mercedes-Benz Forum

Arthur Dalton · #1 05-23-2007, 11:06 AM

OK

Also, when you check it, hold your finger over that vac line and make sure there is vac there when running.
The regulator had a diaphragm in it and what happens is the dia. leaks and then the gas get sucked into the engine through that vac line, causing your erratic rpm behavior..[ unmetered a/f mixture.] fairly common and easy diyer check/fix.

david s poole · #2 05-23-2007, 11:24 AM

pete,been reading your thread and had the same prob with customer car several months ago.it wound up being a separate computer/relay on the floor in front of pass feet.i had assumed that main f.i. computer operated the idle but not the case.i went to salvage yard and found the part and fixed the problem.[this client had gone to expense of changing out the electronic accelerator with no effect]

Pete Geither · #3 05-23-2007, 12:54 PM

Quote:

Originally Posted by david s poole

pete,been reading your thread and had the same prob with customer car several months ago.it wound up being a separate computer/relay on the floor in front of pass feet.i had assumed that main f.i. computer operated the idle but not the case.i went to salvage yard and found the part and fixed the problem.[this client had gone to expense of changing out the electronic accelerator with no effect]

Dave,,,, How did you determine that was the problem.

Arthur Dalton · #4 05-23-2007, 02:50 PM

< >

OK
One more quick thing I would like you to do..

After you get the code 13, I want you to clear it, run the engine after clearing and then turn it off.. Now, go back to same pin [8]and you should get a Single Flash [ code 1] . meaning code is clear..after the single code, wait 2 sec., hold button 6 secs , turn off key for 10 secs on for 50 secs and restart..That will reset the Memory and base line of the HFM module
Take the car for a couple of drives and see what happens..
I still suspect a vac leak [ mat be purge valve] , but do this first, as it a simple thing to do.

david s poole · #5 05-23-2007, 05:26 PM

with my retriever scanner[mb dedicated] i determined that the e.a. had two or three codes that i couldn't erase and when i tried to access the isc it said error no communication.at that point i dug up the etm and traced the wiring back to idle speed computer.i pulled off plug,opened case and bingo burned smell.went and found another for 150 in salvage yard.[i was lucky enough to have similar car in shop and tried that unit first and it worked]

Pete Geither · #6 05-23-2007, 08:21 PM

Quote:

Originally Posted by david s poole

with my retriever scanner[mb dedicated] i determined that the e.a. had two or three codes that i couldn't erase and when i tried to access the isc it said error no communication.at that point i dug up the etm and traced the wiring back to idle speed computer.i pulled off plug,opened case and bingo burned smell.went and found another for 150 in salvage yard.[i was lucky enough to have similar car in shop and tried that unit first and it worked]

Thank you David,,,, if Arthurs' solutions don't work I'll start sniffing around for a burnt module.

Pete Geither · #7 05-23-2007, 08:25 PM

Quote:

Originally Posted by Arthur Dalton

< >

OK
One more quick thing I would like you to do..

After you get the code 13, I want you to clear it, run the engine after clearing and then turn it off.. Now, go back to same pin [8]and you should get a Single Flash [ code 1] . meaning code is clear..after the single code, wait 2 sec., hold button 6 secs , turn off key for 10 secs on for 50 secs and restart..That will reset the Memory and base line of the HFM module
Take the car for a couple of drives and see what happens..
I still suspect a vac leak [ mat be purge valve] , but do this first, as it a simple thing to do.

Did the reset thing when I got home. been driving the SL in this nice weather, and after getting it up to temp, the surge has dissappeared. I am reserving judgement until I get it out tomorrow in hot weather. It never surges when cold and the hotter it gets the worse the surging gets. Thanks for all the help so far.

Arthur Dalton · #8 05-23-2007, 08:30 PM

OK

I doubt you have a ea module problem as mentioned b/c you have/had no communication codes stored...

Pete Geither · #9 05-24-2007, 12:11 PM

OK Arthur,,, what in the heck did we do ? Have been driving the car in the heat today and so far,,, I'm knocking on wood here,,, NO surging or missing at all. Does this eliminate the vaccum leak, or has the engine recalibrated itself to compensate ? I mean this thing is running real smooth today. Thanks again.

Pete Geither · #10 05-23-2007, 12:52 PM

Quote:

Originally Posted by Arthur Dalton

OK

Also, when you check it, hold your finger over that vac line and make sure there is vac there when running.
The regulator had a diaphragm in it and what happens is the dia. leaks and then the gas get sucked into the engine through that vac line, causing your erratic rpm behavior..[ unmetered a/f mixture.] fairly common and easy diyer check/fix.

Good vaccum at the regulator Arthur and no gas whatsoever. No codes on the built in reader but code 13 appears on pin 8 with the code reader.