jb4 tune on 335i

[schutte22]

I have a jb4 tune on my 07 335i and when I put the tunes on and floor it, the car will stop accelerating and the car will shake. How can I fix this?

[328iJunkie]

Misfire. You need coils/plugs

[mcoffey335]

What fuel are you running? My car will detonate on any fuel other than Shell 91, I'm in Canada, all the ethanol blend fuels seem to have the same result regardless of octane rating and even then it's a bit inconsistent. I have a Stage 1 Cobb tune, otherwise stock. Worst for me is Esso 93.

[Jayson13f]

Any update on your problem? I'm curious bc I'm looking into the same tune for my 335.

[328iJunkie]

Jb4 is very relilable. Usually you need new plugs/coils when you get it