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View Full Version : Rough Idle Problem - Cylinder misfiring


CrazyFool
02-23-2006, 06:12 PM
ok... i first thought it was the spark plugs, but it wasnt that.

the next thing thats came to mind were the coil pack, broken spark plug connector, fuel injector or a bent valve.

i am not sure, but when the car idles, it idles pretty rough and you can hear/feel it missing. but when i rev the engine past 1100 RPMs it runs great.

if i let it idle too long, then it misses really bad even past 1100 RPMs. but if i turn the car off then on again, it seems to work properly again at 1100 RPMs. so basically when i start the car or pull up to a stop sign, i am having to keep the idle above 1100 RPMs.

past 1100 RPMs it runs like new.

is this a small problem (like spark or an injector) or could this be a mechanical problem (like a bent valve)?

someone please help me out

shane.reid
02-24-2006, 04:29 AM
I have a _very_ similar problem with my 01 325i

Interested to hear replies...

SoloII///M
02-24-2006, 10:33 AM
My first suggestion would be to run the codes. I would not expect it to be a fuel filter, fuel injector or air filter as those would seriously compromise high-rpm running as well.

Pull the plugs and see if there's something funky going on. If one cylinder isn't firing that plug will be black, whereas the others should be tan or slightly white. It's possible you have oil in the plug wells, or a plug is bad, or a coil pack is bad. Easy to check that.

Barring anything there, run a quick compression test on the engine.

Does your coolant smell like oil? Is your oil foamy when you pull the dipstick out?

JV

CrazyFool
02-24-2006, 01:21 PM
well i ran codes and it said cylinder #5 misfire.

when i pulled the spark plug on the #5 cylinder it was a little moist.

SoloII///M
03-01-2006, 05:34 AM
Did it smell like gas?

My guess would be a bad coil pack - it happens - especially since you said the plugs have already been replaced.

djlonsk
03-01-2006, 10:20 AM
Yeah I think that you blew your head mine did the same thing on the higher rpm's had it checked out and I ended up pulling the cylinder head the valves were bent. I need a new head now. This is what happend to mine. It was overevved and the timing jumped and which caused the valves to misfire and bend i was so pissed.
-David

CrazyFool
03-01-2006, 02:02 PM
Yeah I think that you blew your head mine did the same thing on the higher rpm's had it checked out and I ended up pulling the cylinder head the valves were bent. I need a new head now. This is what happend to mine. It was overevved and the timing jumped and which caused the valves to misfire and bend i was so pissed.
-David
but if your valves were bent then it would be doing it in more than one cylinder, right?

SoloII///M
03-02-2006, 05:01 AM
Yeah I think that you blew your head mine did the same thing on the higher rpm's had it checked out and I ended up pulling the cylinder head the valves were bent. I need a new head now. This is what happend to mine. It was overevved and the timing jumped and which caused the valves to misfire and bend i was so pissed.
-David

It's extremely unlikely the "timing jumped." What's more likely is the valves floated and were smacked by the piston. Very common with a mechanical overrev.

If the head gasket blew, it's possible more than one cylinder would be down on compression. A compression test would show this.

CrazyFool
03-02-2006, 02:37 PM
but only 1 cylinder is misfiring. and if that was the case, then the car would run like **** right?? the car only runs like **** below 1000 rpms.

SoloII///M
03-07-2006, 05:57 AM
but only 1 cylinder is misfiring. and if that was the case, then the car would run like **** right?? the car only runs like **** below 1000 rpms.

Like I said, my first guess is the coil pack is dead. That would be the very first thing I check.

JV

houdini-m3
03-12-2006, 04:12 AM
crazy.......definetly check the oil feed line to your vanos unit, if it is clogged it welll affect the running of the car especially at idle....cheers

houdini-m3
03-12-2006, 04:14 AM
another thing , take out each coil one at a time and check for dampness, and also take out each plug, you may find that the tip is burnt out or even not there, maybe even a loose plug....cheers.

houdini-m3
03-12-2006, 04:15 AM
another thing , take out each coil one at a time and check for dampness, and also take out each plug, you may find that the tip is burnt out or even not there, maybe even a loose plug....cheers.

ImperialDuckM3
03-21-2006, 10:49 PM
If its idle issue during stoping or starting, you would need to look at the ICV (idle control valve). If you're getting misfired, then you're running to rich. This will cause your spark plug to be wet. I recommend you take your car to a trusted mechanic. Most or all of people here is guessing..

lesl2
03-25-2006, 09:52 PM
If you're able to generate a code that points to a cylinder misfiring, then you can move the components around and see if the code changes to another cylinder. Your possiblities in addition to the coil and plugs are the plug wire (short wire between the coil and plug), wiring from the computer and the computer itself.

thekpatricks
06-04-2006, 07:42 AM
Did you ever figure this one out? I have a similar problem on a 1983 533i. I pulled the fuel injectors and they had oil an oil based gunk on the tips, one of the injectors fiber tip came off. When I put things back together it ran the same but I noticed if I pulled the front plug wire (bad injector) it ran the same. Hopefully once replaced it will run better. What could be the cause of the oil on the injector tips? I just bought it and it has been sitting for at least 2 years. I am thinking it may be rings.

CrazyFool
06-04-2006, 01:19 PM
Did you ever figure this one out? I have a similar problem on a 1983 533i. I pulled the fuel injectors and they had oil an oil based gunk on the tips, one of the injectors fiber tip came off. When I put things back together it ran the same but I noticed if I pulled the front plug wire (bad injector) it ran the same. Hopefully once replaced it will run better. What could be the cause of the oil on the injector tips? I just bought it and it has been sitting for at least 2 years. I am thinking it may be rings.
yea... it was a bent valve. a quick $4000 fix. luckily i sold the car before i found out what i twas. the guy told me what it was because he had to fix it.

i sold it for a JDM Integra GSR Turbo. Bimmers are too expensive.


http://img64.imageshack.us/img64/796/dctuner49fe.th.jpg (http://img64.imageshack.us/my.php?image=dctuner49fe.jpg)

thekpatricks
06-04-2006, 05:53 PM
Thanks for the reply, good luck with the new car. Hopefully I will get mine going without too much more expense. I know what you mean about expensive, I just dropped $450.00 on a new OEM set of tail lights. Later.