Misfire after mhd flash

adamjab · 04-29-2016, 07:11 AM

Afternoon. I've just installed mhd stage 1 on my stock 335i 07 Mt. What a difference it makes, it didn't last long though! after about 15 mins I took her out for a good run and as soon as I opened her up the engine light came on and she started misfiring . I'm getting a 29cd cylinder 1 code. But if I turn her off and on again she's back to normal. I'm hoping it's just the plugs. Anyone had similar?

MAN15H · 04-29-2016, 07:46 AM

Could be the ignition coil. I had to replace quite a few of mine when I installed the JB4.

Just pull the one from cylinder one and put it into Cylinder two then run the car again. If it misfires again and this time it says cylinder 2 you know its the coil.

Easy to change and cheap enough to replace.

Aragorn30d · 04-29-2016, 08:06 AM

The increased boost makes the mixture harder to ignite, so can highlight a coil or plug that was marginal before.

Giving it a fresh set of plugs is probably a good idea anyway, and as above, swap the coil around and see if the fault moves.

imy · 04-29-2016, 01:38 PM

Should always change plugs and coils with a tune.

adamjab · 05-01-2016, 09:17 AM

Cheers. Will change plugs then try again

04-29-2016, 07:11 AM	#1
adamjab Registered 0 Rep 4 Posts Drives: e91 335i Join Date: Feb 2015 Location: corby iTrader: (0)	Misfire after mhd flash Afternoon. I've just installed mhd stage 1 on my stock 335i 07 Mt. What a difference it makes, it didn't last long though! after about 15 mins I took her out for a good run and as soon as I opened her up the engine light came on and she started misfiring . I'm getting a 29cd cylinder 1 code. But if I turn her off and on again she's back to normal. I'm hoping it's just the plugs. Anyone had similar?
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04-29-2016, 07:46 AM	#2
MAN15H Lieutenant 46 Rep 505 Posts Drives: G20 BMW 330e MSport Join Date: Jun 2013 Location: The Shires iTrader: (1)	Could be the ignition coil. I had to replace quite a few of mine when I installed the JB4. Just pull the one from cylinder one and put it into Cylinder two then run the car again. If it misfires again and this time it says cylinder 2 you know its the coil. Easy to change and cheap enough to replace.
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04-29-2016, 08:06 AM	#3
Aragorn30d Lieutenant Colonel 175 Rep 1,596 Posts Drives: E90 330d Join Date: Mar 2015 Location: Fife iTrader: (0)	The increased boost makes the mixture harder to ignite, so can highlight a coil or plug that was marginal before. Giving it a fresh set of plugs is probably a good idea anyway, and as above, swap the coil around and see if the fault moves.
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04-29-2016, 01:38 PM	#4
imy Captain 84 Rep 971 Posts Drives: M140i Join Date: Jul 2015 Location: London iTrader: (1)	Should always change plugs and coils with a tune.
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05-01-2016, 09:17 AM	#5
adamjab Registered 0 Rep 4 Posts Drives: e91 335i Join Date: Feb 2015 Location: corby iTrader: (0)	Cheers. Will change plugs then try again
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