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Car is running rich and turbo is pulsating.

9K views 6 replies 3 participants last post by  GSMNZ 
#1 ·
I have a 05 wrx engine that was swapped into a 05 Impreza RS. Im running a stage 2 Cobb map and I have a carless straight pipe, carless downpipe, Perrin carless uppipe and a aftermarket air intake. I noticed whenever I try to go full throttle the car starts running rich like 10.0 at 5+ pounds and the turbo starts pulsating even though I can still hit my target boost of 17psi. I've noticed this morning no matter if it's cold start or warm start the afr reads 10.0 and the builds up to normal running range 14-15's I read somewhere it could be a boost leak or a boost solenoid issue anyone have any ideas?
 
#4 ·
I'm with GSMNZ, my money is on your aftermarket intake. Although in theory it should run lean assuming that it actually flows more air but all sorts of things can happen.

Your Mass Airflow Sensor is calibrated inside the map to a specific shape/diameter of the intake tube. The reading from the MAF sensor defines how much fuel your ECU squirts into the combustion chamber. In closed loop, if you're lucky, the car can compensate for the massive error... however if you go into boost, the car switches into open loop fueling where there is no compensation, it reads the MAF and adds fuel based on MAF reading.

Any change in the intake system, will change the relationship of the MAF voltage -> air volume table to reality.... especially if your intake is a larger diameter than stock where the MAF hangs out. Basically you will have a lot more air moving slower in that case so the ECU just isn't designed to compensate for that and requires a full retune on the MAF table.

Good luck!
 
#7 ·
Look at the MAP requirements on the Cobb Website. Anything other then what is on there can cause many different issues. You probably have a boost leak as well. But call Cobb or any Pro-Tuner and see what they say. This isn't a NA Civic/Neon/Jetta where you can just throw a intake on it an call it good. Subaru's (and many other makes) have very little room for change before you are out of the tolerance it can calibrate for.
 
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