scoob running problem
 

as per title, I've a 1993 wrx, had to change the up pipe. Car went well for a couple of days then, I put my foot down to pull out of a side road got to 3000rpm car noise dived and plumes of black smoke came out of exhaust. Then car was lumpy and hard to keep going... WHEN CAR IS STARTED COLD SOUNDS OK, But when warm is lumpy. disconnected cam and crank sensors, turn it over so it does fire up not, and sounds fine, no piston slap or any other sounds. don't know what else to do as tried compression test. all 4 cylinder's the same

does it always do it or was it a one-off ?

IOf you can get it to do it again, try accelleratign gently at 3000K and see if it's ok then. if so, then I would say coil packs

right ive changed plugs, coil packs, no difference, checked timing belt, spot on. done a compression test. All ok 124psi on each cylinder. looks like ive got to take engine out to see whats wrong, so while this engine is out will need a good cheap replacement

Fuel pressure test ?

Fuel injector seal/leak ?. or good old knackered plug.

fuel pressure ok, tested by a Subaru specialist. fuel rails checked at same time

Coolant sender ? Heard lumpy when cold could the choke as such be set on by ecu telling it's cold so holding the air back and loads if fuel

well its going to a Subaru specialist today, as ive tried every think.

Be interesting to know what it was hopefully nothing too much. only other thing I thought was if you changed up pipe you probably had intercooler off, and your symptoms are very similar to when my intercooler pipe popped off.

Early pipes are brittle and crack when disturbed.

As Rob says above, sounds like a possible boost leak with the I/C pipes. I've had similar.

Well ive had a call today and the scoobs sorted. turned out that the throttle body to inlet manifold gasket was cracked