missfire at high rpm. help [Archive] - Bimmerfest - BMW Forums

: missfire at high rpm. help

10-14-2005, 11:07 AM
can anyone help.
i have a 98 m3 evo (S50) which has an intermitent missfire at high rpm when on full throttle, it normaly starts at about 5500 rpm & sometimes it will not rev above 6000 at all.
i have pluged in my scanner to check the fault codes & it comes up with missfire at coil cyl 3 & 4 (codes 24 & 50). i then tryed swaping the coil packs from cyl 3 & 4 with 1 & 2 to see if the fault changed cylinders but it stil says 3 & 4.
whenever i clear the fault codes it will not missfire at all for a few days & then it will do it randomly.
any help would be apreciated.

10-15-2005, 11:12 AM
I'm stumped, I'm sure you've checked the plugs to see what colour and gap they've got. The coil pack connectors? Injectors dirty? It might very well be that damned intake manifold... I loath it. It seems to get more air to the 3 and 4 cylinders at speed, but that's just my theory...