any help welcome,...1993 classic import wrx only thing i have thats not standard is a apollo air filter.

right i was on my way to nbo and it started .
driving on low revs it is missing and puffing black smoke out and sometimes a small back fire.
on tickover its looks like the engine as a small shudder.
high revs its ok

changed the turbo still same.
just after some advise before i buy coil packs and plugs
thanks daz

NBO was a very good day

 

MAF is obvious culprit with those symptoms.

TPS, because it's cheap, could be worth investigating/changing...

 

thanks for that ,,,i just went out and swopped the maf ,,the small red wire had snapped,,i soldered it back together and now the engine managment light has gone off,,no black smoke but still a missfire and a shake on engine on tick over

 

Try resetting the ECU with the connectors under the steering column, before going any further.......