Idle Problem, Yarr!
I'm new to the whole MB thing, Gm's are what I know. I recently picked up a 190e 2.6 with 87,000 on the clock. I have changed the spark plugs, wires, cap, rotor, fuel filter, valve cover gasket, air filter, all vacuum lines, oil cap, rad cap, motor mounts, tranny mount, new brake pads and rotors in the last 2 weeks (all oem stuff). A couple of days ago the car starting a little weird. Surging while going down the rotor at about 55mph. I checked the spark, it was fine. Check for vacuum line leakage, nothing. Um weird. Well, I went to start it up three days ago. It took it longer than the normal 5 turns to start. Idle was able to be felt in the car. It was like my Trans Am with the 383 and the big cam. I did some research on it. I checked the over voltage thing, no corrosion and no bad fuses. Check the fuses on the car, nothing bad. Um I'm starting to get stumped. I don't really know a lot about the CIS-E system. I don't have a connector the fuel line size so I can't check the fuel pressure. I checked the accumulator, it's fine. I found online about the eha, and tried tweaking that. It ran a lot better till I got to walmart (at red lights it was still a little ruff) . I came out and started it. Fired in 2 clicks, then revved to 1000 rpm. From there is jumped from 1000 to 500 to 1000 to 500 to 1000 with one second intervals. Lasts for about 5 minutes then will idle at 700 like normal. I turned back the eha, still does it. Where do I go from here? Any help would be much appreciated!

I'm new to the whole MB thing, Gm's are what I know. I recently picked up a 190e 2.6 with 87,000 on the clock. I have changed the spark plugs, wires, cap, rotor, fuel filter, valve cover gasket, air filter, all vacuum lines, oil cap, rad cap, motor mounts, tranny mount, new brake pads and rotors in the last 2 weeks (all oem stuff). A couple of days ago the car starting a little weird. Surging while going down the rotor at about 55mph. I checked the spark, it was fine. Check for vacuum line leakage, nothing. Um weird. Well, I went to start it up three days ago. It took it longer than the normal 5 turns to start. Idle was able to be felt in the car. It was like my Trans Am with the 383 and the big cam. I did some research on it. I checked the over voltage thing, no corrosion and no bad fuses. Check the fuses on the car, nothing bad. Um I'm starting to get stumped. I don't really know a lot about the CIS-E system. I don't have a connector the fuel line size so I can't check the fuel pressure. I checked the accumulator, it's fine. I found online about the eha, and tried tweaking that. It ran a lot better till I got to walmart (at red lights it was still a little ruff) . I came out and started it. Fired in 2 clicks, then revved to 1000 rpm. From there is jumped from 1000 to 500 to 1000 to 500 to 1000 with one second intervals. Lasts for about 5 minutes then will idle at 700 like normal. I turned back the eha, still does it. Where do I go from here? Any help would be much appreciated!

The idle control valve on my 2.3 looks like this:

Are both fuel pumps operating?What I would do is, remove the air cleaner and observe what the air flow plate is doing when the idle increases. If it is going down and the idle jumps up, then it is getting vacuum from some source.
I can duplicate your idle problem, 1000 to 500 to 1000 to 500 to 1000 with one second intervals. I'm sure the guys at the MB place will figure it out.
Here's a link to a W201 Service Manual:
http://web.archive.org/web/200606021...01_Chassis.htm
Good luck,
Dave
Last edited by slk230red; Nov 21, 2007 at 10:59 AM.

http://web.archive.org/web/200606021...01_Chassis.htm
A bad fuel accumulator can also cause a low fuel delivery rate.
Also, a clogged filter located at the input of the fuel distributor could cause a low fuel delivery rate. See below photo:

2. You should be using non-resister plugs due to resistance in the OEM connectors, if those are what you are using. I don't think the plugs would cause your problems, but I do know the engine doesn't run as well with resistor type plugs. Which brand/number spark plugs are you currently using?
3. If your engine starts to idle up and down, try disconnecting the connector at the Idle Control Valve to see if it changes.
4. Other things to check:
A. Coil
B. Air Guide Housing (large rubber piece that is between air flow housing and throttle body). Sometimes they are cracked or not seated properly, causing vacuum leaks.
C. Fuel pump relay...known to have cold solder joints on circuit board.
Do you know if the MB guys checked the above items? It's good to keep an accurate log.
Good luck,
Dave
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What was the last thing done to your car before you started having idle problems?
Lately, people have been having idle problems after they clean the throttle housing.
Sensors???
Have you checked the O2 Sensor?
Have you checked the Throttle Position Sensor?
Have you checked the Engine Coolant Temperature Sensor...if yours is the 4 pin type, it sends information to the CFI Module and the Ignition Control Module. Check ohms across pins 1 & 3, and 2 & 4. The resistance will drop as the engine temperature rises. High reading = cold engine. Mine reads 1.7k across pins 1 & 3 and 2 & 4 when checked cold in the morning in the garage.
Check yours and look at the testing procedures according to the manual.
Good luck, I hope you can isolate your problem.
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Photo of cut-off tower:

You might want to check this link about non-resistor spark plugs.
http://www.mercedesshop.com/shopforu...d.php?t=197392
Also, the Fuel Pump Relay is behind the battery. Remove the plastic cover and you will see the FPR along with OVP relay (another problem source, especially if it has a blown 10 amp fuse or corrosion inside). The OVP relay protects the electronics in case of a power surge or reverse battery connection.
You will also see the CFI Control Module.
Example of Fuel Pump Relay:


Cold solder joint:

OVP Relay:


Sounds like you are getting to know your car quite well. Please post what you find out resolves your problem.
Good luck,
Dave
Last edited by slk230red; Nov 23, 2007 at 05:48 PM.
Ya im starting to learn my car lol I knew I would figure something out sooner or later. I havent take it for a ride yet so I dont know If I fixed the stuttering or not. It idle's better, actually at least it will idle. I warmed the car up to 80C and started it a a few times. It started fine. Ill check those things tommrow. Its friggin cold out (38F). Its startin to get better. I guess this is what I get for a car thats 16 years old and sat for 9 years lol Thanks again for the info. Check out those pics and Ill get back to you guys tommrow!

If it were me, and the air/fuel mixture adjustment won't smooth out the idle, then I would start from scratch and go over all of the basics.
Spark plug wires-are they the right type?
Spark plugs- are they the right type?
Coil
Distributor cap
Rotor-there are 2 completely different types for my '93 2.3
Compression test- you could have a burnt valve, or worse...the beginning of a bad head gasket between cylinders.
Fuel pump- pressure/output test
Fuel distributor-is the plunger sticking
Fuel injectors-are they producing the proper spray pattern
Fuel injector seals- are they leaking
Crankshaft Position Sensor- check resistance, or could be dirty at flywheel end.
Just some ideas. I wish I knew the answer to your problem. I know these things can be frustrating.

Dave





