Strange Idle Problem - PeachParts Mercedes-Benz Forum

#1 11-08-2002, 05:28 PM

Ok here is the story on Tuesday when I was coming home from work my car started to surge when I was at a stop light and when I gave it gas it would hesitate and then it would go and be fine but it was doing it every time when I was at idle but the car seemed fine above 1200rpms. So I took my car to Mercedes and they check the fuel system, the ignition system and vacuum system and the only thing they could find was that there was to much resistance from the spark plugs that where used (NGK) because the spark plug wires all ready had resistors in them so they replaced the spark plugs (Bosch) and all was well untill later that day when I was sitting at a stop light and the car surged like it was doing before but now it doesn't do it all the time just every once in a while and it only really seems to do it when the car is warm/hot. So at this point I have searched this forum and mercedes shop and have come to think it might be one of 2 things, the EHA (electro hydraulic acuator) or the ICV (idle control valve) but the dealer said they tested that. So my question is what do you guys think have any of you seen a problem like this before? Oh and my Dad seems to think it might be bad gas (but I only use 92+ octane from Cheveron) or he thinks it might be the rotor and cap and I checked them last night and it seems fine. Oh and I checked the spark plugs wires for cracks and they are in great shape. Thanks for you help.

It seems like XP had this problem did you ever fix it and if so what did you do?

BTW, my car is a 1991 190E 2.3 8-vlv

boili · #2 11-09-2002, 08:46 PM

Hi, I have a 500sel that does exactly the same. all wires, caps, plugs, ignitation control unit, rpm control unit are new and no difference. I gave up on it... since it doesn't happen too often. Every once i a while.
boili

95E320cab · #3 11-10-2002, 10:17 AM

The resistor ends on your spark plug wires are bad. Replace them yourself. I had exactly the same problem. It is an easy fix. The excessive heat caused by the NGKs has burned up the resistor ends. All 6 will cost you about 50 bucks. I just got mine at the dealer as I recall. I GUARANTEE this is your problem!

Dave

mbdoc · #4 11-11-2002, 08:55 AM

Idle problems as described come from faulty sensor imputs to the CIS-e control unit. ON this engine there isn't any hard MEMORY in that computer so the problem must be diagnosed when the problem is happening!