[doomangel]

Hello,

I'm new to the forum and actually DIY.

Summary: I have a 09 335i.
Had some cold start issues a month ago at 88k miles. Leaky injector, so got new index 12s and recoded, with new plugs and coils.

Car is now at 89k miles.
I upgraded the original charge pipe to an aluminium one with BOV. Car was fine for a couple of days, I did push it harder than usual (it's my daily commute/driver) and since last week, I had what seemed like some light misfire during acceleration, between 2000 and 3000 rpms.

A couple of days ago, I tried pushing the car again and finally did get a SES light with cyl 5 misfire code. Cleared it, swapped coils, tried a new plug and still having the misfire when pushing hard.

Since this morning though, even 1/4 throttle or less than 2000 rpm, there is quite a lot of light misfire without code, and if I push the car a tiny bit (pass 2000rpm) I now have SES with cyl 5 and 6!
29D1 / 29D2 / 29CC....


Plugs are not foul, even got new ones again just to validate. Coils have beend swapped again, codes stay in 5 and 6.

The only thing I can think of now is that this car, at 89k miles has never had a walnut blast and half of its life, was doing tons of short trips...


What is your take on it? can carbon build up cause so much misfire? Can the symptoms have been accentuated because I pushed the car to test the new charge pipe?

Thanks a lot for any kind of insight, I kinda really enjoy this car and actually started enjoying DIY on it...

[relative4]

Walnut blast is a good start.