Rough Idle 94 E320 need diagnosis - Page 3 - PeachParts Mercedes-Benz Forum

jsmith · #31 10-10-2002, 09:21 AM

Well, welcome back Steve! I think it's also unusual that no tech other than you has weighed in on this rpoblem. Going through the entire thread I noted that respondees are all forum veterans but none "MB Certified" (at least to my knowledge). Similarly, a recent harness & MAF suspect had the same treatment.

stumbling

I just thought to comment on this aspect of it, not to question the responses from everyone else, whom BTW I all respect. Maybe everyone's real busy right now?

TomO · #32 10-10-2002, 02:00 PM

Quick comments: My wife picked up the car yesterday afternoon; the digital outdoor temp read 80F. She said the car ran really badly and wondered if she'd make it anywhere. By the time she left town for home at 6:30 it was about 50F and the car ran much better.

Everyone's comments so far have been useful; thanks. (I used to think changing my oil was a big deal--I replaced a head gasket last year thanks to a similar bmw forum at roadfly.com)

I bought the Haynes manual and at least now I can better understand the CD ROM, as to what and where some of these parts are; Ritter's book is in the mail.

I'm apparently near the end of what I can do myself at this point. My current plan is to drive the car 500 miles to Denver and take it to a good benz mechanic Oct 25. Until then.....

fyi, twice this past week I got the stock Wyoming comment: "your problem begins with that symbol on the hood".

lewise · #33 10-10-2002, 06:18 PM

Hey I had these same exact problems on my '95 E320 Wagon. It was a bad wiring harness....apparently MB had a bad slew for a bit of time. My car had 95,000 on it when it started happening. I took it to the dealer and argued that I should get some financial assistance on this since it was a documented design problem on those models. MB picked up the price of the part(thank god since it was almost $800) I paid for labor, not bad I think about 2 or 3 hours.. IT fixed everything!!! works great now.

Evan Lewis
'86 300E
'95 E320T

jsmith · #34 10-10-2002, 06:50 PM

Quote:

Originally posted by lewise
I took it to the dealer and argued that I should get some financial assistance on this since it was a documented design problem on those models.

hmmm, tried that one, didn't work. i guess that dealership doesn't know that MBUSA officially denies that there ever was a problem...

lewise · #35 10-11-2002, 09:17 AM

Well here is how I went about it. I first went to NHSTA.gov,(not sure if that's exact address) anyhow did a complaint search and turned up at least 3 formal complaints to the federal gov about wiring harness failures on those model years M104 engine cars ranging from stalling in traffic and causing accidents to full blown vehicle fires. Then I went to www.mbca.org, the car club and did a search and printed out at least a dozen complaints from car club members with the wiring harness problem, I also printed out about a dozen or so threads from this list.................I was adamant with the service advisor(being a fireman and pointing out several "code" violations in the shop probably didn't hurt either). I got a call on my cell phone within a half hour that MB would pick up the tab for the part, along with profuse apologies.

Best of luck to you

Evan

jsmith · #36 10-11-2002, 10:34 AM

excellent post evan! this is could be very helpful to other people who have to go through this ordeal with a dealership.

Arthur Dalton · #37 10-11-2002, 10:46 AM

Sometimes you have to go with the Ultra-Polite tactic and other times you have to go Just short of a Gun...
It's a shame they leave the Head Game to the Customer..

I would love to know how many Benz buyers have gone another Brand cuz of how Benz has elected to handle these [ their] problems.

TomO · #38 10-11-2002, 02:34 PM

....Suginami!!

Yes, you guessed right. Last night, after I rechecked the coils and plug wires, I got out the x-acto knife and did a bit of exploratory surgery. Inside the black sheathing the wires look just like those I've seen photos of--cracked both lengthwise and across.

As they say...denial ain't just a river in Egypt. But somehow it really bothered me to cut into the wiring.

Thanks to Evan for the tips...hopefully I won't need them...And, again, thanks to everyone else who responded. I sure like Dalton's code reader!

jsmith · #39 10-11-2002, 02:46 PM

i compiled the nhtsa docs...

TomO · #40 10-24-2002, 03:40 PM

Obviously this is my call but...

I wrote a polite letter to the dealer I bought the car from last year (thanks, Evan). He and the MB region rep together have offered to cover the cost of the new harness if I pay for the labor and have it installed at a MB dealer. Here are choices I see: 1) Drive 500 miles to a Denver dealer who quotes 6 hours labor or $550 (I already plan to drive to Denver tomorrow anyway). 2) Wait until Thanksgiving and drive 700 miles to the dealer I bought it from (they haven't done any of these harnesses, yet). 3) Flatbed the car to a dealer (my expense). Pass on the offer and buy and install the harness myself.

I haven't driven the car since my last posts: symptoms then were rough irregular idle, especially when outside temp was warm (75 deg +) and drives OK at highway speed but no extra power. I have a new o2 sensor but haven't installed it.

Option #1 looks best to me, but what is the risk?

Thanks.

suginami · #41 10-24-2002, 03:46 PM

I guess the risk would be that you'd replace the wiring harness and still have the same problem.

TomO · #42 10-24-2002, 04:00 PM

Oh, I meant might I fry something electronic?

suginami · #43 10-24-2002, 04:10 PM

Well, my car developed a very bad up and down oscillating idle. After replacing the engine wiring harness, mass air sensor, and throttle actuator, the problem persisted.

Took it to the dealer, and they discovered a bad seal at the intake manifold, causing a vacuum leak. Interestingly enough, the idle was fine when the car was cold. The problem would only manifest until the car was completely warmed up.

Replaced the intake manifold gasket and the problem was fixed.

My situation might be very different from yours and none of it may apply.

TomO · #44 11-06-2002, 11:55 AM

10 days ago I drove 500 miles to Denver and dropped the car off at a MB dealer for a new harness. I paid about $500 for labor, and MBUSA and my original dealer split the part cost. One worry out of the way.

But the car still ran rough. I basically flipped a coin as to whether to leave it at the dealer for another day or take the car to an independent tech with a good reputation, and the independent won the toss. After 3 hours (at $85/hr) he discovered I had a bad coil. I had tried to check it with an ohmmeter but somehow fooled myself. I had gotten good readings by pressing the ohm-meter probes hard against the coil. Apparently the internal connections were erratic. At the time I thought the ohm-meter probes were not sufficiently extended out of their spring-loaded insulators. (Time for a new meter.)

The bad coil had blue-grey stains on its case--maybe from internal arcing. As recall, the other two coils also have these stains, although not as bad. In retrospect I should have bought a spare coil when I replaced the spark plugs, ignition wires and coil-connector boots. (The labor charge savings would have paid for a lifetime supply of coils.)

Thanks again to everyone for your help.

suginami · #45 11-06-2002, 12:01 PM

Man, this is a common problem with this M104 engine.

More often than not, it's a bad connection of one of the three coil wires to the boot resistor end.

Amazingly simple diagnosis. Surprises me that the dealer missed it.