Rough Idle?
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Hey guys,
I have a 1998 328i. I started to have a rough idle that at one point threw a misfire code. The engine also sputters (sometimes) under load at low RPMs, less than 1500, pretty much in all gears. I replaced the spark plugs (since I hadn't since I bought the car), and they all looked okay, except one had a bit of oil on it (not much). The rough idle continued and at one point my car died after I started it. I discovered large cracks on my air boot and the ICV hose. After replacing both I still have the rough idle issue, but it never dies. The RPMs drop to ~500 or less and the car shakes a little bit and sounds like it's about to stall... but it never does. Does this sound like the spark plug coils or something like a dirty ICV?
If the best option is to move the coils around and see if the misfire follows it, does anybody in the Milwaukee area have a code scanner they would lend me for a day or two so I can try to figure it out?
Any help would be great!
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Test your fuel injector. Should have about 16 ohm on it check for pulse it it is in spec.
No sensor will cause a misfire on only 1 cylinder.
If it is a harsh misfire it is ignition related if it is a soft misfire it is fuel related.
1976 530i e12
1990 325ix e30
1992 325i e36
1995 740il e38
2001 330xi e46
^More to come
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Mine was going through rough idle (88 E30) a few months back. Finally cleaned the IACV and have had no issues since. A couple of other things I had going on at nearly the same time were a bad fuel pump, and a leak in the main rubber fuel feed line under the hood. Got all of those issues taken care of, and now she purrs like a kitten.
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Pull your coil for the misfire cyl and check the boot VERY carefully. If the boot is cracked or brittle it can cause a misfire but it is usually under load. I have had one severe enough to cause a rough idle and severe misfire.
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Thanks for the responses. I'm gonna grab a coil today and just see if that fixes anything... after that I'll look into the injectors? Before I replaced my spark plugs I had a misfire on Cyl #2, but didn't put the coils in the same spots (I intended to, but caught myself mixing them up after it was too late).... so I have a sneaking suspicion it is the coil, and it's a relatively inexpensive and cheap fix.
Another question: between the air filter box and the MAF sensor there's a pretty large/thick O-ring that fell out. Where exactly is that supposed to go? Maybe I didn't completely fix my intake problems...
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Mine was going through rough idle (88 E30) a few months back. Finally cleaned the IACV and have had no issues since. A couple of other things I had going on at nearly the same time were a bad fuel pump, and a leak in the main rubber fuel feed line under the hood. Got all of those issues taken care of, and now she purrs like a kitten.
HOw would you describe your idle? I've read that some idles are the engine revving very high. Mine is ~800 and drops towards ~500, oscillating between them. (before I fixed my air boot and ICV hose it would sometimes just stall).
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#4?
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I think that could cause a drivability issue. At that point you are losing metered air which could cause the AFR to be off.
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jc43089 is right about which one it is,
That O-ring came out, and my tabs have since broken. I think I mounted the O-ring incorrect (on the outside of the MAF lip), which made the tension in the tab holders too high and snapped it
Zip-ties do the job fine, but the O-ring is maybe supposed to be inside the air filter box half?
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