E90 N52 misfire moves cylinders

dpm123 · 01-30-2018, 06:06 PM

Woke up one morning last week and started my car and immediately noticed it was running rough. Drove down the street and the service engine soon light came on. I read the code with a cheap scanner and it was a misfire on cylinder #1. So I took it to the shop, they found injector #2 to be faulty and replaced it. Then they said the misfire showed up on #3. They ran some more tests and finally said that everything checked out mechanically (plugs, coils, injectors, compression) and they think it's the computer. I didn't want to pay their estimate to have it tested/repaired so I told them I wanted to pick it up. After they put it back together the misfire moved to cylinder #4. Has anyone seen this type of misfire before? Do you think the computer could be an issue? I actually removed it last night to do a continuity check on the MOSFETs like I'd seen in a couple of other posts but they were fine. And I didn't see/smell anything that looked remotely fried. Is there anything else I should check before sending my computer in for repair? Would really appreciate anyone's input. Anything helps. Thanks.

dpm123 · 01-30-2018, 10:45 PM

Well, tonight I had a look for myself. Did a cylinder drop test by unplugging each coil while the car was running. Once I found the problem cylinder (#4), I swapped its coil with #2. Didn’t bother reading the code, instead I did another drop test and saw that the misfire moved to #2. Bought a new coil from advance and now the car runs great. I guess the moral is don’t rely on the scanner. I’m hoping that’s the end of that...

Keebs64 · 01-31-2018, 08:12 AM

I had a similar issue a couple of weeks ago... Very cold morning start, and the car idles & runs rough, with a reduction in power. Take it to the shop- Misfire on #5. Replace #5 coil and the car is back to normal for the rest of the day.

The next day- Another very cold morning start, and the car idles & runs rough again. Back to the shop to find out there's a misfire on #4. Replace #4 coil and the car is back to normal. It's been normal since the second coil replacement.

The mechanic told me that after replacing the second coil, #1 showed a misfire, but after clearing the code & rescan, it never came back.

01-30-2018, 06:06 PM	#1
dpm123 New Member 0 Rep 8 Posts Drives: 2006 325i Join Date: Jan 2018 Location: Raleigh iTrader: (0)	E90 N52 misfire moves cylinders Woke up one morning last week and started my car and immediately noticed it was running rough. Drove down the street and the service engine soon light came on. I read the code with a cheap scanner and it was a misfire on cylinder #1. So I took it to the shop, they found injector #2 to be faulty and replaced it. Then they said the misfire showed up on #3. They ran some more tests and finally said that everything checked out mechanically (plugs, coils, injectors, compression) and they think it's the computer. I didn't want to pay their estimate to have it tested/repaired so I told them I wanted to pick it up. After they put it back together the misfire moved to cylinder #4. Has anyone seen this type of misfire before? Do you think the computer could be an issue? I actually removed it last night to do a continuity check on the MOSFETs like I'd seen in a couple of other posts but they were fine. And I didn't see/smell anything that looked remotely fried. Is there anything else I should check before sending my computer in for repair? Would really appreciate anyone's input. Anything helps. Thanks.
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01-30-2018, 10:45 PM	#2
dpm123 New Member 0 Rep 8 Posts Drives: 2006 325i Join Date: Jan 2018 Location: Raleigh iTrader: (0)	Well, tonight I had a look for myself. Did a cylinder drop test by unplugging each coil while the car was running. Once I found the problem cylinder (#4), I swapped its coil with #2. Didn’t bother reading the code, instead I did another drop test and saw that the misfire moved to #2. Bought a new coil from advance and now the car runs great. I guess the moral is don’t rely on the scanner. I’m hoping that’s the end of that...
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01-31-2018, 08:12 AM	#3
Keebs64 New Member 6 Rep 29 Posts Drives: 2006 330i Join Date: Mar 2013 Location: New York iTrader: (0)	I had a similar issue a couple of weeks ago... Very cold morning start, and the car idles & runs rough, with a reduction in power. Take it to the shop- Misfire on #5. Replace #5 coil and the car is back to normal for the rest of the day. The next day- Another very cold morning start, and the car idles & runs rough again. Back to the shop to find out there's a misfire on #4. Replace #4 coil and the car is back to normal. It's been normal since the second coil replacement. The mechanic told me that after replacing the second coil, #1 showed a misfire, but after clearing the code & rescan, it never came back.
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