Friend is chasing down a missfire at around 4k.
Coils and plugs replaced.
225k miles
Stock save aftermarket Mass Air Sensor.
Occurs with most any load, but not no-load.
Occurs with waste-gate only boost of 145kPa

Fueling is next thing under suspicion.

Thoughts? DNM

 

I don't know anything about WRXs specifically, but maybe cam angle sensor not giving accurate position and thus not advancing timing?

 

The “aftermarket air mass” has my mechanic senses tingling, but without codes or looking at OBD2 data, it’s hard to tell.

 

OBD2 scanner is only showing a mis-fire on Cylinder 2.

When original MAF was put on, car really ran terrible, I was told.

Nevertheless, I will pass that on.

 

Aftermarket MAF had a crack in it. New Denso unit fixed the problem.

@curly

DNM

 

Woot

 

That was a beast experience flex haha. Nice.