Made the appt. to have the diagnostic check done on my car(rough idle still),Jan.22,at (Souverign MBZ,Bklyn,NY),dealer said because of the year and the history of these cars it's a 4 to 5 hr. job and I'm looking at $400. to $500. Does this sound right? I don't know, sounds awfully high AND this doesn't include actually FIXING the d**n car.

Damn Richie, for that kind of time and money you could almost have a major tune done! When mine was idling a little rough, my tech carged me for a spark plug wire connector and 1 hour diagnosis - problem fixed. I'd take it to a good independent first.
Before I gave the dealer that kind of $$$ I would check the search button on rough idle and see what others found. I would be inclined to check plugs, cap and rotor, plug wires and connectors, fuel filter, and O2 sensor, and fuel pump if all else failed.

Good luck!

How rough is it? We have the same model year. Mine stumbles through idle, but it's very subtle and not much of a problem. I second what JCE suggested that you check. In addition, you may also have the original injectors (like mine) which apparently don't like premium gasolines as they are currently formulated. There is a thread in which I discussed what my tech told me about rough idle in my 300E and what I tried (regular instead of premium) as an experiment. Do a search under my username and you'll find that thread. The guy who started that thread said that his injectors were replaced and ultimately the fix on his was as simple as JCE's (as I recall). If your idle is REALLY bad then I may be running off without my mouth connected anywhere sanitary and I apologize.

If they quoted you this over the phone, they are scared of it because it is old.

Beware. I would use a KNOWN GOOD independent.

David:
Thanks for kicking some of the plaque loose on my Alzheimers. After you mentioned injectors a (dim) bulb came on, and I went out and looked at my service records. The tech that did the plug connector also told me I had a bad injector seal/sleeve. I had him do all the seal/sleeves at the same time. It was $81 parts and labor for the injector seals and sleeves, and $21 for the plug connector. 95% of the roughness gone.

Richie:
For comparison, $400 at my tech was the cost of a complete 60,000 mile service including tune up with new plugs and filters, and trans/power steering fluid and filters, diff lubrication replacement, oil and filter change, lube of sunroof, doors, hood, adjustment of fuel mixture, etc etc etc. $400 to just to look at it is a rip! (IMHO)

Thanks guys
 

THIS QUOTE WAS IN PERSON!!I GUESS I LOOK LIKE JOE NECKBONE! They actually wanted to push my appt. up to tomorrow. NO THANKS!! Have just put new Beru wires on, idle cleared up alittle, tomorrow will try new plugs. Everything else mentioned was just changed. There was an independent shop suggested to me, but I figured why not give the dealer a shot. NOT! I guess I'll try the independant shop after all. My brother laughed and said,"I told you Mercedes was expensive". Yeah, but not that expensive.

dtanesq: other than the occasional stumble when idling, the car runs great(to me anyway). I believe that they are the original injectors,not 100% sure though.

Forgot to add, the dealer believes it might even turnout to be an electrical wiring problem. For $400/$500, they might as well do the whole harness:D.

[Edited by rich30769 on 01-11-2001 at 12:42 AM]

rough idle
 

My 420 SEL just went through a major surgery as a result of the timing chain follower deal. After initial startup, the check engine light came on and they changed the O2 sensor. Now I have severe rough idle and at 75 can feel it in the wheel. I hope the solutions I've seen suggested to your problem work for me. The shop immediately wanted to replace the fuel distributor. Thanks. BTY, is the lambda harness just a "T" or does it have components in it? And will a digital multimeter work or does it have to be analog?