Cylinder 1 Misfire...swaptronics not helping...

Luther_S · 08-20-2021, 05:10 PM

What's up guys,

My first post. I have been lurking this forum for the past 3 years, but not super vocal when I don't feel I have good info. That being said I have what I feel is a solid question.

I went to a highly recommended repair shop specializing in European vehicles. Lot is flooded with BMW/Audi/Porsche/etc, and lots of good reviews. Anyways:

TA's were ready so I had them swap new ones in. when they finished they went to fire it up and it wouldn't start. fuse was popping. Cylinder misfire 1. and the usual other codes. popped a COP in and fired right up. also did plugs and oil at that time. 2 weeks later. same code. goes into limp mode. I can get it to just say emissions error if I drive for a bit then restart. seems to do ok at speed/+2000 rpms. wait for it to cool and same thing. bring it back. they swap coil on 1 and 2. I guess 2 was burnt and smelled like it. ok cool. pop a new coil on 2 and it fires right up. take it for a test drive and call it done. I get there to pick it up and it goes into limp mode AGAIN. they scan and it's Cyl 1 misfire AGAIN. before I got there I also told them to check Header Gasket because I've been reading things here. He says it looks good. swaps injectors and does a compression test and everything is good there...but still misfire on 1. I have them doing the O2 sensor on that side, and both if it works. He's talking about going to the DME after this!!! Any help would be greatly appreciated. Only thing I've done to the car so far is wheels, so no mods yet, not even an intake. can you guys come up with any other issues?!! appreciate the help!

Ajolives · 08-20-2021, 05:27 PM

Odd problem; seems like a due diligence issue on the shop's part to me based on what I read. Did they check their work? They suspect the DME just went bad all of a sudden? Why/how? Don't mean to plant the seed of doubt but seems fishy to me that they can't solve a misfire if they're a well respected shop.

Second thought, were the TAs brand new or rebuilt?

fs34 · 08-20-2021, 10:33 PM

Check the grounding on the engine harness. You have to remove the plenum, there are 3 of them. 1 in front behind the thermostat housing. The other 2 are in the back on the drivers side. Similar issues with mine and this was the problem. Mine was from a TBA install where the shop didn’t put the nuts back on, maybe that’s the case here. Good luck on finding the problem.

Luther_S · 08-23-2021, 04:43 PM

Quote:

Originally Posted by Ajolives

Odd problem; seems like a due diligence issue on the shop's part to me based on what I read. Did they check their work? They suspect the DME just went bad all of a sudden? Why/how? Don't mean to plant the seed of doubt but seems fishy to me that they can't solve a misfire if they're a well respected shop.

Second thought, were the TAs brand new or rebuilt?

TA's were brand new OEM. Nothing wrong with questioning the shop, I did/do myself but I trust them not to screw me over, if that makes sense. I think he just assumed the coil would do it, I also know they are busy as shit so they might be rushing. He wouldn't charge me for anything that wasn't needed though. I have him replacing the O2 sensor and if that or the grounding on the harness isn't it it's time to start talking serious with the guy.

Luther_S · 08-23-2021, 04:45 PM

Quote:

Originally Posted by fs34

Check the grounding on the engine harness. You have to remove the plenum, there are 3 of them. 1 in front behind the thermostat housing. The other 2 are in the back on the drivers side. Similar issues with mine and this was the problem. Mine was from a TBA install where the shop didn’t put the nuts back on, maybe that’s the case here. Good luck on finding the problem.

Thanks for the suggestion, I haven't seen this one yet. I will definitely bring it up to the Tech!

Luther_S · 09-13-2021, 07:39 AM

Hey all,

anyone following or interested the culprit was indeed the O2 sensor, and only the side for the misfire. I changed both banks after the first was successful. I found a lead on these forums so I just wanted to add to the information.

Thanks for the help!

Redd · 09-13-2021, 06:59 PM

Thanks for the update. Strange that O2 sensor would cause only a single cylinder misfire. Usually it's the whole bank.

08-20-2021, 05:10 PM	#1
Luther_S Registered 6 Rep 4 Posts Drives: '12 E92 M3 Join Date: Aug 2021 Location: WI iTrader: (0)	Cylinder 1 Misfire...swaptronics not helping... What's up guys, My first post. I have been lurking this forum for the past 3 years, but not super vocal when I don't feel I have good info. That being said I have what I feel is a solid question. I went to a highly recommended repair shop specializing in European vehicles. Lot is flooded with BMW/Audi/Porsche/etc, and lots of good reviews. Anyways: TA's were ready so I had them swap new ones in. when they finished they went to fire it up and it wouldn't start. fuse was popping. Cylinder misfire 1. and the usual other codes. popped a COP in and fired right up. also did plugs and oil at that time. 2 weeks later. same code. goes into limp mode. I can get it to just say emissions error if I drive for a bit then restart. seems to do ok at speed/+2000 rpms. wait for it to cool and same thing. bring it back. they swap coil on 1 and 2. I guess 2 was burnt and smelled like it. ok cool. pop a new coil on 2 and it fires right up. take it for a test drive and call it done. I get there to pick it up and it goes into limp mode AGAIN. they scan and it's Cyl 1 misfire AGAIN. before I got there I also told them to check Header Gasket because I've been reading things here. He says it looks good. swaps injectors and does a compression test and everything is good there...but still misfire on 1. I have them doing the O2 sensor on that side, and both if it works. He's talking about going to the DME after this!!! Any help would be greatly appreciated. Only thing I've done to the car so far is wheels, so no mods yet, not even an intake. can you guys come up with any other issues?!! appreciate the help!
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08-20-2021, 05:27 PM	#2
Ajolives Captain 922 Rep 933 Posts Drives: E90 M3 Join Date: Mar 2019 Location: Tampa iTrader: (0) Garage List 2019 Audi SQ5 [0.00] 2008 BMW M3 [0.00]	Odd problem; seems like a due diligence issue on the shop's part to me based on what I read. Did they check their work? They suspect the DME just went bad all of a sudden? Why/how? Don't mean to plant the seed of doubt but seems fishy to me that they can't solve a misfire if they're a well respected shop. Second thought, were the TAs brand new or rebuilt?
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08-20-2021, 10:33 PM	#3
fs34 Lieutenant 397 Rep 417 Posts Drives: E46 M3 Join Date: May 2019 Location: Huntsville, AL iTrader: (1)	Check the grounding on the engine harness. You have to remove the plenum, there are 3 of them. 1 in front behind the thermostat housing. The other 2 are in the back on the drivers side. Similar issues with mine and this was the problem. Mine was from a TBA install where the shop didn’t put the nuts back on, maybe that’s the case here. Good luck on finding the problem.
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09-13-2021, 07:39 AM	#6
Luther_S Registered 6 Rep 4 Posts Drives: '12 E92 M3 Join Date: Aug 2021 Location: WI iTrader: (0)	Hey all, anyone following or interested the culprit was indeed the O2 sensor, and only the side for the misfire. I changed both banks after the first was successful. I found a lead on these forums so I just wanted to add to the information. Thanks for the help!
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09-13-2021, 06:59 PM	#7
Redd Brigadier General 3900 Rep 4,165 Posts Drives: 2010 BMW E92 M3 Dakar Edition Join Date: Jul 2015 Location: Malaysia iTrader: (0)	Thanks for the update. Strange that O2 sensor would cause only a single cylinder misfire. Usually it's the whole bank.
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