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Help! Persistent but intermittent misfire. At the end of my rope!
Hi Guys, I desperately need some help.
My e60m5 has a misfire I cannot seem to cure but the odd part is it goes away and the car runs 100%. Then it comes back again. This leads me to believe it’s not something physical/mechanical.
The codes I get are the ‘cylinder misfire effecting emssions’. Then ‘cylinder misfire with cutoff’ then ‘multiple cylinder missfire’ I also reliability get o2 sensor at limit position (like due to misfires). I also have the airbag error from the ‘resistance to high’ on the cable in the boot that has the emergency battery disconnect.
I have tried:
Full set of the reccomended ngk spark plugs
Full set of brand new coils (the oem/bremi ones)
Both bank 1 ionic module and bank 2 ionic module (also brand new oem).
The symptoms are like this:
At cold start it runs horribly and immediately goes into ‘reduced power’ (aka limp mode). At first it’s so rubbish the car barely drives. With about 2 minutes of driving it warms up enough that it’s running better. After 5 min when oil temp is around 90c I turn off the car and restart and it’s running fine with just an occasional slight miss. If i get stuck in traffic idling for extended time it will usually hit limp mode again. If I’m on a freeway drive it runs very nicely. It’s happy to pull up to an easy 150mph.
I’m happy to do the alternator but blowing a bunch more money doesn’t appeal if it won’t fix it. The coils and ionics did nothing.
I’m wondering if it could be a bad coolant temp sensor?
Some of the codes:
2B3C - missfire cyl 8 with cutoff
2B49 - missfire cyl 8 impairing emssions
27AA - 02 sensor at limit bank 1 pre cat
The fact that this issue can come and go tells me it’s likely a sensor or some electrical issue.
Any thoughts greatly appreciated!