HELP!! Idle problem mystery!! M119 E420
 

Hey everyone! Problems once again with the '95 E420. I apologize for the extensive post. Here's a link to the previous posting of the problem and the potential solutions I've tried:

http://www.peachparts.com/shopforum/tech-help/250446-1995-e420-rough-idle-m119.html

Problem: The normal slight idle miss has been occurring for the past couple of years but has not been severe enough to really be able to hunt down the culprit. (The list of possible fixes are in the previous post) In a nutshell, the most recent problem occurred following letting the car sit for 3-4 days last week. Upon starting the car, it chugged for a few seconds and died. Fired it again and the engine was idle hunting and then wouldn't do anything but chug on 6-7 cylinders producing a nice sulfur smell from the cats going nuts over the unburned fuel. The miss seemed to jump between cylinders, and when put into Drive the car would simply die.

Most Recent Solution: This shot at the problem was a long one but still a good maintenance job. There was a little oil visible at the top of the #4 cylinder's plug tube so I was guessing that maybe the plug (potentially others as well) had become fouled from oil seepage from the valve cover gasket following the car's sitting. So I pulled the valve covers and replaced all of the gaskets, oil transfer tube seals, as well as new spark plugs. To no avail, upon restart, the problem persisted. NOW comes the screwed up part!!

Because the miss seemed to jump between cylinders we looked once again at the distributor caps. (Mind you, we have replaced them 3 times already) We took out the Right Cap and swapped it with the same cap from our '95 S500 and the car ran just fine. The usual slight miss but no longer any chugging or dying. This points to the cap being shot. (the cap looked fine by the way...no major signs of any carbon tracking) So we installed the same cap on the S500 and the car ran perfectly. WTF???

Am I missing something here?? Why would simply removing and reinstalling a cap have any bearing on how the car runs?? It points to a faulty wire connection maybe but those have been replaced twice already as well. Does anyone have ANY insight into what the hell is going on?? (pardon my French) Voltage related maybe??

PS...no CEL or DM codes, but I am getting an unassumingly related ABS light following maybe 1 out of every 40 or so starts which is a "Solenoid Valve Relay" code....but I'm just assuming it's a dirty wheel sensor.

Anyone??

I already weighed in on that other thread but you haven't responded yet.
Regards, Eric

You said that the miss seemed to jump between cylinders. How did you determine this? I had a slight intermittent miss with my old 400E and I could never figure out which cylinder it was to begin with, not to mention being able to tell that it jumped to another cylinder. I don't mean to be argumentative--I'm just curious.

Just viewing the response of the engine and how intermittent the miss actually was is why I used the term "jumping". It was clearly more than just a single cylinder mis-fire. I didn't run a scope on the engine though so I can't say 100% that it was jumping cylinders, only that it was for sure more than one.

400Eric, the car does not have ASR.

Keep me posted!

Every once in a while my E420 will hesitate for no apparent reason. I think it might just be the EGR at work. I pretend not to notice it because it only happens occasionally.

The next thing on my list for trying to resolve the problem is replacing/cleaning the EGR pipe/valve. Intake manifold is a LOT more work than the valve cover gaskets and oil transfer tubes.

The EGR valve can be replaced in ten minutes, but to clean out the EGR passageway on the 119, I think you have to take the intake manifold off. I'm not convinced that EGR passageway obstruction is a recurring issue with the 119.

Quote:
Originally Posted by dproudfo http://www.peachparts.com/shopforum/...s/viewpost.gif
Also disconnected MAS to see if the idle improved; no result.


It would seem to me that disconnecting that should have caused some kind of reaction, the fact that it didn't makes me think something's amiss with it.

"From what I've researched about a failed ETA is that they either work or they don't. (There isn't an "in between" where they'll cause slight problems)"
When the insulation on all those wires inside those things go bad, they sometimes cause problems, but sometimes they work fine, just like when the main harnesses go bad, stuff works sometimes, sometimes it doesn't. I would think this would be less of an issue on a non-ASR car though. Does your car have ASR?

You would have been better served if you kept this all on one thread.
Regards, Eric

you can feel the shake of the engine shift a bit when it misses on alternating cylinders.

Take a look at the wiring harness for the insulation flaking off.

I think he mentioned in the first thread that the harness was replaced but I'm not sure. This is another reason why it would've been good to keep this topic in one thread instead of two.
Regards, Eric

I know I should have kept this problem on the same thread but the attempts at resolving and the recent "major' problem prompted me to start a newer/updated post. Any insight in addition would be great!!

Thank you!!!

I didnt see coils or coil wires in any of your replacement issues. Crank position sensor on the back of the motor/front of tranny could be an issue. O2 sensor, EZL, computer module. All those things can cause spark issues.

I wasn't aware there was one on the back of the motor until reading this. Sure enough, the epc shows one for the 119. I always thought the only crank position sensor was the one at the crank damper on the front, which I believe the epc called a TDC sensor (I presume now the two are different). A search on this forum for crank position sensor for the 119 doesn't reveal much information about it. Is this something that has been an issue on the 119?