Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 02-15-2000, 02:43 PM
Posts: n/a
Help! I've owned this Euro 16V for several years, purchased @ 55K mile; now @ 125K miles, mostly highway. The car is eurospec to the best of my knowledge (no cat, no O2 sensor, no charcoal canister).

Since I've had the car, I have had an intermittant (worse now) problem with engine performance. At low rpm, under load the car sometimes stutters, and then "kicks in" when rpms get high enough. At high rpm I will get white smoke from tailpipe.

The fuel pump and filter are new; idle air mixture valve about 3 years old, cap and rotor are new (wire resistance checked out okay last year), the chain and tensioner were replaced about 2 years ago, water temp sensor new (comparing US vs euro models I've noticed there are 4 sensors clustered near water sensor at front of engine vs 3 on euro, and 2 air temp sensors on air box on the US model vs. 1 on the euro - ?)

Some observations: new spark plugs seem to help for a liitle while (few hundred to a few thousand miles), they appear to foul quickly (black carbon soot), oil accumulates in the low end of the air box (might this be getting sucked through the engine at high rpm?), the car seems to run better when it is raining (moisture in air apparently increasing apparent octane rating of fuel). I also notice a "stickiness" of the accelerator pedal when starting to depress it- I tried to lube linkages under hood, but might not have done a good job, or could this be coming from a sticky flapper itself? Also, do the injectors go bad?

I recently asked the dealer to "fix," and as far as I can get out of them they compression tested the engine and said it was "very high." They supposedly adjusted idle, and changed the plugs and charged a lot for that. The car runs the same.

Their explanation: "compression ratio too high for US fuel." I don't buy it; car runs the same on 92 or 93 or 94 octane, and the owners manual says to use MON 88, RON 98, so in US (RON + MON)/2 = 93. I have the manuals (plus 16V supplement) and can do some things myself and need some help!! I love the car but am at my wit's end! but before I start throwing parts at the car - which at least is better than spending money at the dealer to NOT diagnose the car, at least by throwing new parts in the car I have something to show for the money.......

Thanks for your help.

Reply With Quote
Old 02-15-2000, 07:27 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
They are wrong. The compression is a little higher, but I'd bet that the ignition coil is breaking down. I have seen this before on these. Does it ever stumble while cold? I have seen this symptom with the coil as well.

1981 280GE SWB
1987 16V

Reply With Quote
Old 02-15-2000, 08:38 PM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Before spending too much money, have the valve been adjusted? How much compression did the engine have?? Also have a cylinder leak test performed to see if the pistons & rings are in good shape. A good chance of oil consumption causing build-up.


[This message has been edited by M.B.DOC (edited 02-15-2000).]
Reply With Quote
Old 02-16-2000, 10:17 AM
Posts: n/a
That is interesting about the coil; I believe there is a simple resistance check for the coil (which I did last year), and I recall it checked okay. Could it see dielectric breakdown under operation, which wouldn't be picked up by such a test?

As for the compression test, the only info. I was able to get (so far) is "200 lbs compression per cylinder."

I will try to find out if they did a leakdown test.

The valves were not adjusted; would this contribute?

Also, the oil I find accumulating is in the airbox (which houses the air filter), and it must somehow be getting sucked to that point through the breather hose which is connected to the valve cover. Is this common or normal?

When cold and starting the engine, without touching the throttle, the engine sometimes turns quite a few times, and sometimes starts right off; regardless, it will sit right at 900 rpm at idle. But, after touching the thottle, and then letting it idle as the rpms come back down towards 900 rpm it will keep dropping towards ~ 400 rpm at which point it starts to bog (you can sometimes hear bearings start to chatter), and then it will climb again to above 900, and will cycle like that. It doesn't do it always, and seems to do it less when the engine is fully warmed up.

I can't tell you how much I appreciate your help.

Reply With Quote
Old 02-16-2000, 11:06 AM
David Hendy's Avatar
Registered User
Join Date: Jun 1999
Location: New Milford, Ct
Posts: 892
I have just sold my US spec 16V. However, it sounds to me (with my limited knowledge) that you car is running very rich on idle. On the US cars there is an adjustment just behind the airbox that controls CO at idle. When I adjusted the screw too much, so the idle was too rich, on start up, with the cold start engaged, the engine would hunt up and down, until the engine warmed to normal operating temperature. I know that on US spec cars the CO adjustment can control alot of the problems from the injection systems.

The best guy to talk to is Adrian Eckenrod, he knows his stuff, I think his email is

David Hendy
Reply With Quote
Old 02-16-2000, 11:20 AM
Posts: n/a
Yes, I suspected the idle was a problem, that's why I went to the dealer. They supposedly adjusted the idle, but I can't be sure they did it correctly. But if it was adjusted properly, perhaps excess fuel is still getting to the plugs due to leaky injectors?
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
w108 engine problems sa_w108 Tech Help 2 01-23-2005 08:23 PM
the 1994 - 200 Mercedes Benz C280 engine overheating problems ascona Tech Help 3 07-23-2003 11:40 AM
!!!! wanted 16v engine !!!!!! daveCT Mercedes Used Parts For Sale & Wanted 0 07-04-2003 01:16 PM
some engine problems ned2683 Diesel Discussion 7 03-27-2003 05:48 PM
warranty on 3.5 6 cyl engine mercedesmatt Tech Help 3 01-26-2003 03:33 PM

All times are GMT -4. The time now is 07:36 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page