Possible injector issues?

BMWRog · 03-03-2023, 03:01 AM

My F12 M6 currently has 44100 miles on the clock. Cold starts at ambient temp of around 7C (44F) results in an initial slightly lumpy tickover for about 1 minute or so. Then it seems to sort itself out and run smoothly. My last oil lab analysis (oil change at 4000 miles) was deemed satisfactory, with no fuel dilution measurable.

Am I right in thinking this might be an injector issue? I am running on the original injectors, with plugs and coils having been change 4000 miles ago.

TinCanSailor · 03-03-2023, 11:02 AM

It could be the MAF sensors or possibly the O2 senors. If I were to bet it would be the post cat O2's but would not rule out injectors. I think 50k miles is the high side of when you'd want to replace them and given these engines consume oil which will soot up everything from the cats back to the exhaust tips if they haven't been changed yet it would be in good form to go ahead. There are some diag routines in ista that can test for injector issues or if you have something like jb4 you could do some logging and post to the jb4 forums.

SWFLf10 · 03-03-2023, 07:13 PM

I thought the post cat sensors didn’t affect the engine parameters? I thought they were only used for monitoring of the cat’s efficiency?

Just something I read somewhere online. I’d love to hear more if you have some info on this.

TinCanSailor · 03-03-2023, 10:24 PM

Quote:

Originally Posted by SWFLf10

I thought the post cat sensors didn’t affect the engine parameters? I thought they were only used for monitoring of the cat’s efficiency?

Just something I read somewhere online. I’d love to hear more if you have some info on this.

That is correct. Had a lot of plates in the air and 4 of them were pads, rotors and sensors for my daughters e93. The pre cats are the ones that will measure burn chemistry of air/fuel. Apologies for the mix up.

BMWRog · 03-07-2023, 03:01 AM

Thanks for replies. I think a visit to the local BMW agent is going to be called for. I'd rather replace the injectors now, than have a problem develop later on. The engine does not appear to be burning any oil - no top ups required between oil changes. And since the battery is now 9 years old, that will need replacing soon as well. I've also just been notified of a safety recall regarding the driver's airbag, so maybe get all of it done together!

03-03-2023, 03:01 AM	#1
BMWRog Private First Class 19 Rep 126 Posts Drives: 2014 M6 Convertible Join Date: Feb 2017 Location: Oxfordshire, U.K. iTrader: (0)	Possible injector issues? My F12 M6 currently has 44100 miles on the clock. Cold starts at ambient temp of around 7C (44F) results in an initial slightly lumpy tickover for about 1 minute or so. Then it seems to sort itself out and run smoothly. My last oil lab analysis (oil change at 4000 miles) was deemed satisfactory, with no fuel dilution measurable. Am I right in thinking this might be an injector issue? I am running on the original injectors, with plugs and coils having been change 4000 miles ago.
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03-03-2023, 11:02 AM	#2
TinCanSailor Fueled by Recycled Dinosaurs! 630 Rep 1,171 Posts Drives: F06 M6 Join Date: Dec 2019 Location: 813Bay, Fl iTrader: (2) Garage List 2015 BMW M6 Gran Coupe [9.75]	It could be the MAF sensors or possibly the O2 senors. If I were to bet it would be the post cat O2's but would not rule out injectors. I think 50k miles is the high side of when you'd want to replace them and given these engines consume oil which will soot up everything from the cats back to the exhaust tips if they haven't been changed yet it would be in good form to go ahead. There are some diag routines in ista that can test for injector issues or if you have something like jb4 you could do some logging and post to the jb4 forums. __________________ 2015 F06 M6 Silverstone Metallic II, Individual Full Leather, B&O, Night Vis, CCB, RKAutowerks (CP Rods/Pistons, DI Cams, CF Intakes, Coated DP's & Billet Diff Brace), InfinityAuto Turbo Inlets, Mishi Oil Cooler, JB4, XHP S3, BM S3
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03-03-2023, 07:13 PM	#3
SWFLf10 Captain 374 Rep 639 Posts Drives: 2016 Alpina B6, 2015 535i Join Date: Jun 2018 Location: Florida iTrader: (0) Garage List 2016 BMW Alpina B6 ... [10.00] 2015 BMW 535i [8.83]	I thought the post cat sensors didn’t affect the engine parameters? I thought they were only used for monitoring of the cat’s efficiency? Just something I read somewhere online. I’d love to hear more if you have some info on this.
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03-07-2023, 03:01 AM	#5
BMWRog Private First Class 19 Rep 126 Posts Drives: 2014 M6 Convertible Join Date: Feb 2017 Location: Oxfordshire, U.K. iTrader: (0)	Thanks for replies. I think a visit to the local BMW agent is going to be called for. I'd rather replace the injectors now, than have a problem develop later on. The engine does not appear to be burning any oil - no top ups required between oil changes. And since the battery is now 9 years old, that will need replacing soon as well. I've also just been notified of a safety recall regarding the driver's airbag, so maybe get all of it done together!
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