Idle problems + bad cold start
Thread Starter
Newbie
Joined: May 2021
Posts: 4
Likes: 0
190 2.0
Idle problems + bad cold start
Hello MBworld,
I have a problem where my car idle goes between 500-1200 rpm but the weird thing is sometimes it runs fine but usually the idle goes up and down. It always starts immediately but if it's colder it dies immediately so I have to start it several times and pump the gas to get it a little bit warmer and then it's fine.
The car is 1989 2.0 Fuel injection and automatic.
I have a spare parts 190 that runs fine so I've tried swapping a lot of parts.
OVP Relay tried swapping + bought a new with 2 fuses
ICV (idle engine)
Tried adjusting co2 and idle values (did it with a mercedes mechanic friend)
New plugs and wires
Air temperature sensor
Thermo vacuum valve
Microswitch
I tried this test: https://mbworld.org/forums/e-class-w...diagnosis.html and test 1 was fine but test 4 was not. Every time the car revved the voltage went to 6-8.8V and then down to 0.5-2V until it revs again after a few seconds and its at 6-8.8V again and then down to 0.5-2V for a few seconds. What does this mean is the lambda broken?
Many have suggested in the past that it's an air leak but I've tried checking the hoses and haven't found any + if it was an air leak wouldn't it ALWAYS run bad? I also checked if the microswitch gets voltage and it got all kinds of values up to 16.4V
I have a problem where my car idle goes between 500-1200 rpm but the weird thing is sometimes it runs fine but usually the idle goes up and down. It always starts immediately but if it's colder it dies immediately so I have to start it several times and pump the gas to get it a little bit warmer and then it's fine.
The car is 1989 2.0 Fuel injection and automatic.
I have a spare parts 190 that runs fine so I've tried swapping a lot of parts.
OVP Relay tried swapping + bought a new with 2 fuses
ICV (idle engine)
Tried adjusting co2 and idle values (did it with a mercedes mechanic friend)
New plugs and wires
Air temperature sensor
Thermo vacuum valve
Microswitch
I tried this test: https://mbworld.org/forums/e-class-w...diagnosis.html and test 1 was fine but test 4 was not. Every time the car revved the voltage went to 6-8.8V and then down to 0.5-2V until it revs again after a few seconds and its at 6-8.8V again and then down to 0.5-2V for a few seconds. What does this mean is the lambda broken?
Many have suggested in the past that it's an air leak but I've tried checking the hoses and haven't found any + if it was an air leak wouldn't it ALWAYS run bad? I also checked if the microswitch gets voltage and it got all kinds of values up to 16.4V
Last edited by derolivan; May 12, 2021 at 10:24 AM.
MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
Your original post seems to indicate that the idle issue only happens after a cold start and now you're saying that the idle issue can happen if the car is both hot or cold? I'm trying to help you but I need you to describe exactly when the car is having the idle issue so I can better help you determine what the problem might be. Maybe also if you could post a video of the car when the idle issue is happening might help.
Thread Starter
Newbie
Joined: May 2021
Posts: 4
Likes: 0
190 2.0
Your original post seems to indicate that the idle issue only happens after a cold start and now you're saying that the idle issue can happen if the car is both hot or cold? I'm trying to help you but I need you to describe exactly when the car is having the idle issue so I can better help you determine what the problem might be. Maybe also if you could post a video of the car when the idle issue is happening might help.
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MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
The reason for asking for specifics on what the temperature is when the idle is rough can sometimes mean a different possibility for what the problem might actually be. The lambda test failure is a possibility but I also can't help but wonder if it might also be a fuel delivery issue where there's a partial clog in the fuel system that once it gets punched out, the car runs fine. Have you checked the fuel filter, made sure that the fuel lines are clear and is the gas tank in good shape with no large amount of residue in the fuel tank that might cause any type of clogging? I would also make sure that all of the wiring in the engine bay is in good condition and that all of the connections are nice and clean with no debris or gunk on them. In addition, check all of your rubber hoses to make sure they're in good condition and don't have any tiny cracks in them. You might also go to your local auto parts store and buy some engine dye and run that in your engine to see if that shows any leaks anywhere. I would suggest you start with the really easy stuff first and then work from there. I'm also at a disadvantage in that my W201 is a North American 2.3 engine and I know there are differences between my car and your European 2.0 version. I'll certainly still try to help you.
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