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irratic idle

2181 Views 10 Replies 5 Participants Last post by  azatrum
My 88 190e 2.3 idles a little rough but smooths out when you apply a little pressure on the accerator. I've replaced spark plugs, wires and distributor cap.
Any suggestions where to start?
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Mercedes 28E 1993 (W124)
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119 Posts
the dreaded 201 sickness :D

Youve probably worked out that the 201's suffer from the never ending problem of rough idling....

Providing youve done the obvious things like plugs, leads etc, then Id look straight at the idle control valve.....its situated behind and below the air filter, YOur local dealer can test it..

josh
 

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erratic idling and worse

My '92 190E 2.3 also idles rough. Furthermore, I recently changed the spark plugs and now it not only idles more rough but it hesitates badly when accelerating. The spark plugs were the "EON3", and my car is listed in the application table, so they should be suitable. Can they have broken my HT leads? In that case, should the car go that way, that is, not too bad in the highway but with fire missings?

By the way, my1st88, did you change the spark plugs, leads, rotor and cap by yourself? I am about to do it, so any advice will help.
Best regards.
 

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erratic idling and worse

My '92 190E 2.3 also idles rough. Furthermore, I recently changed the spark plugs and now it not only idles more rough but it hesitates badly when accelerating. The spark plugs were the "EON3", and my car is listed in the application table, so they should be suitable. Can they have broken my HT leads? In that case, should the car go that way, that is, not too bad in the highway but with fire missings?

By the way, my1st88, did you change the spark plugs, leads, rotor and cap by yourself? I am about to do it, so any advice will help.
Best regards.
 

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What is the common fault of that idle control valve, can it be fixed by cleaning it? how?
...


What is the common fault of that idle control valve, can it be fixed by cleaning it? how?
By the way, is the rough idling a design fault or it appears only when something gets bad? Did the brand new car idle ok?

Best regards
 

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1991 190E 2.6
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7 Posts
my 1991 had that problem occur after a high speed run on the freeway. same as you describe. I sprayed carb cleaner in to throttle body at 2000 rpm. I used about 1/2 can. If you look at the mouth of the throttle body you may see that the throttle plate is gummed up. after doing this everything was great.

Steve
 

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What problem did you cure, the erratic idling or the shakes and misfires?
You mean sprayi...


What problem did you cure, the erratic idling or the shakes and misfires?
You mean spraying that into the plate by removing the air filter cover? What do you mean with the throotle body gummed up?
Thanks!
 

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1991 190E 2.6
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spray it good

When I came off the highway the idle was "hunting" up and down between stall speed and 2000 RPM. I sprayed 1/2 can into the throttle plates with the air cleaner taken off and it degummed the throttle body and returned a normal idle(750rpm). I ran the car while doing this with a helper keeping the speed to about 2000 rpm . I used about 1/2 can to insure that the entire system got clean. I also put 1 bottle of fuel injector system cleaner through a tank of gas. I work at a Dodge store. We do this type of cleaning to fuel injected cars all the time. I checked with the Mercedes dealer before doing it. They perform this type of service as well. Within a few days of doing this service I did as well:

replaced plugs
replaced plug wires
replaced distributor cap and rotor
changed the oil and filter
changed the transmission fluid and filter
replaced the air filter
replaced the brake fluid
replaced the power steering fluid
replaced the power steering filter

I noticed a complete change in personality in the car. Although this car was in good shape I have learned from my work that do not trust any system on a used car you have not serviced yourself. By doing this service my cars acceleration and gas milage got much better. The idle problem is just the cars way of telling you "I need Love". Pay attention to it and you will be glad.

Good luck

Steve
 

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Well, really my idle is not so bad: you only notice vibrations in the engine, and the re...

Well, really my idle is not so bad: you only notice vibrations in the engine, and the rev. gauge doesn't nearly move.

Where can I found that carb cleaner you talk about? Do you just spray it over the fuel distributor plate that is below the filter?
Another question about spark plug wires: what if one of them is broken? The car seems to run with all four cylinders, but sometimes it shakes, specially when pushing from low revs, other times it doesn't. I have heard that, if a cable is broken, it can still produce spark but it is less intense. What do you think?
Best regards,

Sergio
 

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1995 S-420
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I have in a way the same kinda problem with my 190 E, but i wouldnt call it an irratic idle, its more of a shake in the engine on low rpm's, on high rpm it gets ok. I got it examined by a mercedez dealer and they told me that one of the injectors or what ever u wanna call it in the "fuel distributer" is running rich, which causes the shake.Also on low rpm's i sometimes can smell gas while seated inside the car. Now does that mean that i have to replace the distributer or it could b fixed by the tune up? any suggestions?
 
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