BMW E46 RANDOM MISFIRE

Updated: 09 Dec 2024

Hey guys so recently I’ve been having misfires at certain rpms, the most prevalent being at 2nd gear between 2000-3000 rpm when I give it some gas. There are no codes showing up and I changed the spark plugs 4 months ago but I bought another set 3 days ago just in case one was faulty but it still misfires hard.

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Also I was hoping to replace the coil of the misfiring cylinder but since no codes show up I dont know which one to replace

Engine?

What do you mean?

There are Youtube videos on how to test your coil packs. You will need to take them out and use a multimeter to test for continuity.

This is what id do. But keep in mind its not 100% its like 99% accurate but i have found a few test good and be bad. First one took me 6 hours to figure out cuz it tested good so i ignored it till just for kicks cuz i had one laying around tryed a new coil. I had spark and the engine ran so (one coil engine) just ran like crap and would not rev up.

U can also try driving it and then touching eatch of the coils see if one is noticeably hotter than the others then that one is NFG (no f-ing good)

swap coil packs and read out which cylinder it is

There are no codes tho so he cant read out the bad one

U know the more i think about it the more im thinking we are all looking at the wrong part. Im starting to think we need to look at the injectors. Could be sticking or not able to keep up with the demand causeing what feels like a misfire but its enough to not throw a code

Could be but Ill also check my ignition coils just in case one is starting to fail

I know this isn’t much help but I had to.

Basically what every BMW comes with that system from the factory😂😂

You know, this may be a little extreme, but you can go disconecting the sparkplugs one by one (keeping allways 3 spark plugs conected) to see wich cilinder misfires.

Had this issue on my 330ci, quick way to test is to spray WD40 in potential culprit areas. Drive after each test and when it stops, well bobs your uncle and Fanny’s your aunt. It’s not a perm fix but should clear any moisture out temporarily long enough for you to know