ok its on my m3, but i still need help and you lot are a lot more hands on than most bmw owners. lol



its an e36 3.0 gt
basically i fitted a decat pipe and backbox to the car last year, and this year it has rough running problems, i think its down to fitting these but wonder what you think.

the car is ok most of the time but occasionally it misfires, to stop the miss you have to let off the throttle completley and then reapply, usually this makes it ok.

i have had it on scanners and it never shows a fault with any sensors,
1 of the o2 sensors is new,

i plugged it in today and drove it down the road with the scanner attached, when it played up i help the figures on the screen for all sensors and nothing was abnormal.
the only thing that did show up as strange was that its charging 15.5v at any revs inc. idle,

do you think this could be the problem???

the car is std except for the decat and backbox, and its got a smaller front crank pulley, meaning the alternator is spinning at a different speed to normal, but this was fitted long before the decat and it was ok back then.

ive changed the coils, plugs, afm, tps, checked everything and still no joy, but my m8 whos a mechanic thinks it could be the 15.5v thats doing it.


thanks in advance