[notabmwfan]

08 320i with 2.0L (Japanese RHD)

Rough idle all of a sudden and check engine.
Had it scanned - P0301 (misfire cyl #1)

So I check and unplug the #1 ignition coil while the car is running, no change in idle, so there is a good chance it is a bad coil. So I swap it with coil #2 and do the same and no change in idle when I disconnect #2 coil.

I live on a small island, and it is very difficult to find parts here. But I found one and even though the part number wasn't exactly the same, the guy said it should work.

My part # is Bosch 0221 504 100 and he had 0221 504 470 (it fits and connects perfectly)

So I put it in the car and the idle seems better but not great... And check engine is still on. I tried disconnecting Neg on Battery for a few hours and then driving the car around the block, still not great idle and check engine won't go away.

**** my questions is ****

Has anyone changed their own ignition coil and still experienced rough idle problems until they had their check engine light reset?

[///Mposter]

Originally Posted by notabmwfan

08 320i with 2.0L (Japanese RHD)

Rough idle all of a sudden and check engine.
Had it scanned - P0301 (misfire cyl #1)

So I check and unplug the #1 ignition coil while the car is running, no change in idle, so there is a good chance it is a bad coil. So I swap it with coil #2 and do the same and no change in idle when I disconnect #2 coil.

I live on a small island, and it is very difficult to find parts here. But I found one and even though the part number wasn't exactly the same, the guy said it should work.

My part # is Bosch 0221 504 100 and he had 0221 504 470 (it fits and connects perfectly)

So I put it in the car and the idle seems better but not great... And check engine is still on. I tried disconnecting Neg on Battery for a few hours and then driving the car around the block, still not great idle and check engine won't go away.

**** my questions is ****

Has anyone changed their own ignition coil and still experienced rough idle problems until they had their check engine light reset?

Usually check engine lights go off after the problem goes away, especially after a misfire, and lots of time after with no misfire.

Your spark plug might be fouled on #1, and when you put it to #2 that plug might have been saturated with fuel and fouled as well.

Also, since you are unsure about the new part, make sure the parts length is identical to the old. Also make sure that when you are installing it that you pay close attention to the orientation of the coil. Some models have grooves and the coil has or is shaped like “>” on one end of the top. If you mistakenly press down while it is oriented wrong, you will be short by 1/4” or more. That could cause it to arc from the coil to plug for that cylinder.

[///Mposter]

Attached photo of what I discussed above.

[nvturbo]

Should have replaced the spark plugs too...because more than likely, one or more are fouled.