N55 misfire after shop visit

Smooth_Operator · 01-31-2024, 11:31 PM

How can I test for a misfire without going WOT?

For context, I had my 2013 N55 in the shop for a valve cover replacement. Shortly after doing this, I smell burning oil. I pop the hood, and see oil all over the valve cover. I get on the phone with the shop that did the repair. As I'm on hold, I glance at the coils, and notice that two of them are different. When I took the car in to the shop, all 6 coils were the original Delphi coils with the beige tops. Somehow, after visiting this shop, two of them are the Bosch coils with the grey tops. I (or rather CarMax, thanks to the warranty) was not charged for coils. I ask about this on the phone, and ask again after I take the car back in for the 'leak.'

Apparently there was no leak, they just made a mess and didn't clean it up properly. As for the coils, they noticed a misfire on cylinders 3 and 4, and just replaced the coils without telling me. They swapped the Bosch coils for two new Delphi coils, without me asking. But who am I to complain about new coils?

Anyway, shortly after this, I have the car on the highway. It's empty, no cops, straight line, perfect time to open the taps a bit. As soon as I go WOT, the engine stutters. Obvious misfire. I slow down and take it easy to my destination. When troubleshooting a couple days later, I go WOT again, and the car goes into limp mode. I pull codes, which are confusing. I think I got 'misfires on multiple cylinders,' but the only cylinder that's specifically called out is cylinder 2. I order 4 new coils to replace the remaining original Delphi coils.

As I was replacing coils, I noticed that old coil number 2 had what looked like oil inside the part that plugs in to the wires. I've noticed no misfires since, but the only event that triggered them before was going WOT. I haven't floored my car since. Is there a way I can tell if I fixed the problem without flooring my car, or should I just suck it up, floor it and see what happens? Should I be concerned about cleaning the plug that plugs into the coils?

Car is tuned MHD stage 1 with an intake, otherwise stock.

thejeremyman9 · 02-05-2024, 06:23 PM

If i understand what part you are talking about that had oil (electrical connector), you can get the aerosol electronic cleaning spray and clean that out. A bad connection there could be an issue.

In addition to pulling codes, before and after you do a WOT pull to see what pop up, make sure you log the pull. https://f30.bimmerpost.com/forums/sh....php?t=1732327

01-31-2024, 11:31 PM	#1
Smooth_Operator Private 73 Rep 59 Posts Drives: F30 BMW 335i 6MT Join Date: May 2022 Location: USA iTrader: (0)	N55 misfire after shop visit How can I test for a misfire without going WOT? For context, I had my 2013 N55 in the shop for a valve cover replacement. Shortly after doing this, I smell burning oil. I pop the hood, and see oil all over the valve cover. I get on the phone with the shop that did the repair. As I'm on hold, I glance at the coils, and notice that two of them are different. When I took the car in to the shop, all 6 coils were the original Delphi coils with the beige tops. Somehow, after visiting this shop, two of them are the Bosch coils with the grey tops. I (or rather CarMax, thanks to the warranty) was not charged for coils. I ask about this on the phone, and ask again after I take the car back in for the 'leak.' Apparently there was no leak, they just made a mess and didn't clean it up properly. As for the coils, they noticed a misfire on cylinders 3 and 4, and just replaced the coils without telling me. They swapped the Bosch coils for two new Delphi coils, without me asking. But who am I to complain about new coils? Anyway, shortly after this, I have the car on the highway. It's empty, no cops, straight line, perfect time to open the taps a bit. As soon as I go WOT, the engine stutters. Obvious misfire. I slow down and take it easy to my destination. When troubleshooting a couple days later, I go WOT again, and the car goes into limp mode. I pull codes, which are confusing. I think I got 'misfires on multiple cylinders,' but the only cylinder that's specifically called out is cylinder 2. I order 4 new coils to replace the remaining original Delphi coils. As I was replacing coils, I noticed that old coil number 2 had what looked like oil inside the part that plugs in to the wires. I've noticed no misfires since, but the only event that triggered them before was going WOT. I haven't floored my car since. Is there a way I can tell if I fixed the problem without flooring my car, or should I just suck it up, floor it and see what happens? Should I be concerned about cleaning the plug that plugs into the coils? Car is tuned MHD stage 1 with an intake, otherwise stock.
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02-05-2024, 06:23 PM	#2
thejeremyman9 Major General 4461 Rep 7,733 Posts Drives: 2015 BMW 335i Join Date: May 2019 Location: Cali iTrader: (0)	If i understand what part you are talking about that had oil (electrical connector), you can get the aerosol electronic cleaning spray and clean that out. A bad connection there could be an issue. In addition to pulling codes, before and after you do a WOT pull to see what pop up, make sure you log the pull. https://f30.bimmerpost.com/forums/sh....php?t=1732327
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