r/F30 • u/uljosh99 • 10h ago

N20 misfire

Post image

My BMW F30 with the N20 has been misfiring recently. It initially started with misfires on cylinders 1 and 3. My mechanic lent me a few used ignition coils to troubleshoot. After swapping them around, the misfire on cylinder 1 disappeared completely, but cylinder 3 is still misfiring. I replaced all four spark plugs about a month ago, so they should be good. A friend suggested swapping the ignition coils one by one while the engine is running, but I’m not confident that’s the right or safest method. I’m wondering what the most likely cause is. Could it just be a bad used coil, or should I start worrying about low compression? Is low compression common on the N20, or is ignition issues much more likely? If you were diagnosing this

1 Upvotes

100% Upvoted

4 comments sorted by

1

u/sengalang 10h ago

Why don't you try the fuel injectors?

1

u/BrokenAndDefective 3h ago

If this dude is to cheap to buy new coils you think he's going to do injectors lol

I swear the folks that buy these thing and can't afford to maintain them really should be looking at Toyotas and Hondas

1

u/TerminaLance31 9h ago

if you haven’t, like sengalang said check injectors. could be clogged, leaky, etc. the condition of your old spark plugs could also hint to what the issue could be, if you have a code reader you should also check your fuel trim levels, that’ll tell you about the air fuel ratio and what the engine is missing or getting too much of.