Rough idle, really rough in the cold
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2006 C230 Sport
Rough idle, really rough in the cold
2006 C230 Sport - started having a rough idle at low RPM a couple weeks ago. Above about 1,200RPM, it runs fine. One cold morning (35 degrees) it was running really rough, wouldn't rev. After a couple blocks I pulled over, turned it off and restarted, back to the regular rough idle at low RPM....have replaced the fuel filter and MAF....any other suggestions?
Next day - had the really rough running problem in middle of commute on interstate - wasn't cold - wouldn't rev up, couldn't accelerate and felt like it was running on 2 cylinders. Pulled off interstate, turned off engine, let sit for a minute, restarted and it was back to just the rough idle at low RPM.
Next day - had the really rough running problem in middle of commute on interstate - wasn't cold - wouldn't rev up, couldn't accelerate and felt like it was running on 2 cylinders. Pulled off interstate, turned off engine, let sit for a minute, restarted and it was back to just the rough idle at low RPM.
Last edited by tylerc230; Oct 18, 2017 at 03:13 PM.
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Joined: Jul 2002
Posts: 591
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From: Mid-Atlantic USA
W203 & W204 3.0L 4matics & MR2 Supercharger
How many miles, looks like you have the M272 E25 so once you get around 80K to 100K it's going to need new motor mounts, this wont cause the stalling issue but will cause a rough idle.
Does the car warm up? Any codes?
NP
Does the car warm up? Any codes?
NP
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Joined: Dec 2012
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2006 C230 Sport
Has about 140,000 miles on it. For the last couple weeks, the problem has always been there, warm or not. There were those couple times when there seemed to be hardly any power at all at any RPM. The engine is in the Balance Shaft affected range, but not getting those codes. Codes I am getting are P0300, P0301, P0303 & P0304 - that's all.
Interestingly, I unplugged the new MAF (Bosch) and it seemed to idle/run fine. Could it be a defective MAF? I also noticed that there seems to be a low hissing/sucking sound from the back side of the engine..... Also, my engine cover doesn't have that metal wire clip at the back side that I believe is supposed to hook over the notch on the top of the cover, which I have seen on some of the videos (not sure if those were same engine) - cover seems to seat properly though.
I appreciate any input NP!
Interestingly, I unplugged the new MAF (Bosch) and it seemed to idle/run fine. Could it be a defective MAF? I also noticed that there seems to be a low hissing/sucking sound from the back side of the engine..... Also, my engine cover doesn't have that metal wire clip at the back side that I believe is supposed to hook over the notch on the top of the cover, which I have seen on some of the videos (not sure if those were same engine) - cover seems to seat properly though.
I appreciate any input NP!
Last edited by tylerc230; Oct 20, 2017 at 11:42 AM.
Super Member
Joined: Jul 2002
Posts: 591
Likes: 3
From: Mid-Atlantic USA
W203 & W204 3.0L 4matics & MR2 Supercharger
It's miss-fire city, if you might try replacing all the spark plugs first, it's on both side of the engine so it might be both CATS but it's cheaper if you're
going to shotgun parts at it to start with the plugs, you might want to make sure the MAF is seated and sealed correctly the might be where hissing
is coming from.
NP
going to shotgun parts at it to start with the plugs, you might want to make sure the MAF is seated and sealed correctly the might be where hissing
is coming from.
NP
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C230 K
So did you figure it out? If I was hearing a hissing noise, I'd suspect a vacuum leak, which definitely can cause misfires on all cylinders. Make sure the intake is seated correctly over the throttle and there are not holes/cracks between the maf and throttle. If thats good, I'd try another maf, it shouldn't run better by disconnecting it. I had an Eclipse once that took three new mafs before I got one that worked. They seem to be one of the harder electrical parts for manufacturers and aftermarket companies to get right. The next thing that would suspect is upper O2 sensor(s). These are directly responsible for air/fuel mixture. It is very unlikely that several plugs or coils or injectors went bad at once causing multiple misfire codes. It is most likely an input the the ECM causing your issue. MAF, O2, ECT, BARO, etc.. I wouldn't keep driving the car like that, you will destroy your cats.
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