C-230 Kompressor Rough Idle - PeachParts Mercedes-Benz Forum

JDM · #1 12-05-2012, 06:37 PM

Hi, I need some help..I have a 2000 C-230 Kompressor. I bought the car used with 60,000 miles, ran great. But unfortunately I let the fuel filter go to 125,000. One day while driving on the highway it backfired a little bit and then started to sputter.

I figured immediately it was the fuel injector.

I changed the fuel filter which only helped a little bit, then I started using Lucas fuel cleaner which didn't do much, then I tried small amounts of transmission fluid which helped maybe a little.

The car still has power and is good at high speeds ( 60+mph ) although I can still hear a slight sputter which comes back when stopped.

I went to AutoZone and they hooked the car up to a computer and told me the number #1 cylinder was misfiring. I think it is a fuel injector since I've changed the spark plugs.

Any help is appreciated.

mbdoc · #2 12-06-2012, 08:35 AM

Most likely issue is the spark plugs (special for Kompressor engines!), spark plug wires, or coils.

JDM · #3 12-06-2012, 06:50 PM

Quote:

Originally Posted by mbdoc

Most likely issue is the spark plugs (special for Kompressor engines!), spark plug wires, or coils.

Thanks mbdoc, and to be honest I never changed the plugs either, so they had 125,000 on them too. I replaced the plugs with the original Bosch. The number#1 cylinder (which should be at the grill) was burnt to a crisp and the others as well but not as bad. I should have taken pictures of them.

I was afraid to change the fuel filter because it was the only car I had at the time and needed it to get to work. And at a previous time I took the plugs out at 90,000 but they looked OK and the car ran good, so I let it go. I never knew how easy MB's are to work on until I got on this site, and I'm just talking the basic maintenance of course.

So how do I know for certain which is bad? The spark plug wires looked fine as far as I could see, and the coils (from the outside) looked OK. Is there a way to test them first? If I could get out of this jam that easy, then I'll consider myself very lucky since changing plugs and wires is much easier than fuel injectors, at least for me.

mpolli · #4 12-06-2012, 08:22 PM

How rough is the idle? If you are running on 3 cylinders then that is more like barely running. When I had a bad coil I was running on 3 cylinders. When I had a rough idle I changed plugs and plug connectors (2). That worked, but since I did both at the same time I don't know which did the job.

mbdoc · #5 12-07-2012, 08:16 AM

Moving the coils & wires to see if the problem moves with them, would be a good starting point.

JDM · #6 02-07-2013, 08:00 PM

Quote:

Originally Posted by mbdoc

Moving the coils & wires to see if the problem moves with them, would be a good starting point.

I just tried moving the wires and there was no difference in the idling, the plugs are brand new. I was thinking it could be the fuel injector, how would I know for sure?

mpolli · #7 02-08-2013, 02:43 AM

How rough does it idle exactly? My friend has the '99 and had the same complaint. We changed the motor mounts and he says it is like a new car.

JDM · #8 02-08-2013, 02:39 PM

Quote:

Originally Posted by mpolli

How rough does it idle exactly? My friend has the '99 and had the same complaint. We changed the motor mounts and he says it is like a new car.

As if were running on three cylinders until there is an increase in rpm's. I'm thinking it could be a dirty fuel pump, the pressure seems to be low.

mpolli · #9 02-08-2013, 05:19 PM

I would think the problem would be opposite, worse performance when it needs more fuel. Have you measured the fuel pressure?

Did you ever move the coils as MB DOC suggested?

No CEL? I would think if it is running that rough you would get a code.

JDM · #10 02-14-2013, 12:25 PM

Quote:

Originally Posted by mpolli

I would think the problem would be opposite, worse performance when it needs more fuel. Have you measured the fuel pressure?

Did you ever move the coils as MB DOC suggested?

No CEL? I would think if it is running that rough you would get a code.

I didn't switch the coils if that's what you mean but I pulled and twisted the wires, plus I checked the ends and didn't see any burn marks. I decided to replace the number #1 fuel injector and see what happens. The problem started with a bang and then it sputtered from that point on. I had Autozone check and they said the number#1 cylinder had a misfire, when I accelerate it gets smoother. I bought a rebuilt fuel injector last week and I'll start working on it today, I think that's the problem.

JDM · #11 02-16-2013, 05:17 PM

I just got done changing the injector but there's no difference, I was told the number #1 cylinder was misfiring so I replaced the injector at the front of the engine. I'm not sure if that was number #1 or if was in the rear of the engine.

Would anyone know which is the number #1 cylinder?

mpolli · #12 02-25-2013, 12:49 AM

1 is near the firewall I think. The odds are it is the coil not the injector. There are 2 coils: one fires 1 and 4 and the other fires 2 and 3. I would swap the coils and see if the misfire moves to 2 or 3. That was the case on mine. And the common wisdom is to replace the "connectors" that are under the coils also. They look like rubber dog bones. Good luck.