driveability problem 95 E420....
 

We have a 95 E420 with a random problem,the rpms fluctuate at idle,it will sometimes stall when coming to a stop,(always starts right back up),will buck/lurch under normal acceleration and at cruise speeds.We've had this car to the dealer in OKC 2 times,engine wiring harness replaced,throttle accuator replaced,tune-up etc. the 2nd time they drained all the fuel and replaced all the filters,flushed the fuel system and tank.Picked it up and still had the same problem(they said it was a bad throttle accuator)when I said they had replaced that the last time they said they put a used one in.I said it really doesn't matter they put it in and it didn't fix the problem therefor they should stand behind it and make it good.Didn't happen.Removed the throttle acc. and sent it out to be repaired,came back as no faults found.they said it was probably the e-gas module,sent it out,they called today and said it had 3 componets that were reading bad,told them to repair it ($489 w/shipping),should be back by the end of the week.My question,after the history lesson is this,where do we go from here if this does not correct our problem?Has anyone else had similar problems and if so what did you do to correct them?Sorry about the long post but thought the history would save a lot of questions,thanks.

There are 3 computers that are responsible for the "correct" running of the engine!

You have a fuel computer, ignition computer, & throttle actuator computer.

HAS anyone ever hooked up a scanner & read codes from those engine system computers?

That is where I would start.

I'm not sure,we assumed that was done when it was at the dealer having the engine harness and throttle accuator replaced,I guess I should have remembered what assumed means.Can we scan this with your normal Auto Zone type scanner or will we need something more upper end? Thanks for the reply

No, that requires a dealer type of scanner...NOT ODB2

Thanks again for the reply.I thought that was the case with this car.I'm really reluctant to take this back to the dealer after previous bad experiences(to the tune of $4600 1st time,$700 2nd time) and still having the same troubles.Hopefully the e-gas module will fix the problem.I can get the engine management computers bench checked for $55 each,that's probably less than what the dealer would charge us to run the scans.

Are you saying an authorized MB dealer installed a used part on your car that you didn't ask them to??
Dealers are not allowed to install used parts, at least not while I worked there (82-99).
If you have an invoice see if they charged for a new part. Would have been around $1200.
What amazes me is they told you the replacement was bad. Don't they check your repair history before giving you a diagnoses?

<<engine management computers bench checked for $55 each,that's probably less than what the dealer would charge us to run the scans. >>

You may want to just built a LED test tool [ $10] an go get the codes yourself.

Here's the codes for each module . Your chassis has the 38 pin Diagnostic plug. [ OBD1]

http://www.geocities.com/MotorCity/Downs/1039/mercedes/cs1000_mb.pdf


..and here is the tool.

http://www.peachparts.com/shopforum/showthread.php?t=107630

These are only Flash Codes ,but it will give you a direction.
Post results.

Arthur,thanks for the reply and the links.Talked to the rebuilder today and he said we should have our repaired unit back on monday.Will install it sometime next week and see if that corrects the problems we were having.Still going to build the LED code reader for future use.Will post the outcome next week as soon as I know something.

Very good.
Build the tool and when all is back togeter , I would go into the modules in a few days just to see how everthing is running.
Hopefully, you will only get a Single Flash for each, meaning No Faults Detected/Stored..........
Give the car a few good drive cycles/days for the Modules to adapt before getting codes.

What amazes me is they told you the replacement was bad. Don't they check your repair history before giving you a diagnoses?[/QUOTE]
Clark, to answer your question yes they installed a used part(they wanted $1400 something for a new one,$600 something for a used).We picked up the car the 1st time drove it 2 miles to a gas station for fuel,it was still showing the same symptoms,we thought we would run a tank or two of gas through it and see what happened.Took it back again 2 weeks later when we picked it up same thing,that's when they told us it was a bad throttle accuator.Decided then that we would not take the car back to MB would do it ourselves.