2011 Subaru WRX, will only run if I have my foot on the gas pedal

[Simply_Richard]

Just a little update tuner made a map forcing the car open loop and no change, AFR is still super rich

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[bp05obxt]

This is an interesting one..

Is the car running a cobb flex fuel kit? I assume it is with the description but it technically only says flex sensor so I wasn’t sure. If so has there been any attempt to remove the flex kit and try returning to pump gas on just the factory harness? Cobb flex kits have been known to fail or have odd issues.(the factory harness could have issues too; anything is possible)

A random thought I also have considering you did a smoke test did you check the brake booster independently. I’d struggle to see it causing this much trouble but potential it has failed internally and only causes running issues due to pulling air into the system. You are on SD so again I don’t see that being likely but a smoke test or boost leak test wouldn’t show anything with the check valve in place on the booster vacuum line.

I have seen ethanol mess up injectors even if they are rated for Ethanol. One thing you could check is on the top of the injectors there may be SS filters/screens that may have corroded causing the injectors to not work as they should. This will cause the car to run sporadically.

A couple thoughts..

[Simply_Richard]

Originally Posted by jphil101

Or what about the MAF sensor

Originally Posted by bp05obxt

This is an interesting one..

Is the car running a cobb flex fuel kit? I assume it is with the description but it technically only says flex sensor so I wasn’t sure. If so has there been any attempt to remove the flex kit and try returning to pump gas on just the factory harness? Cobb flex kits have been known to fail or have odd issues.(the factory harness could have issues too; anything is possible)

A random thought I also have considering you did a smoke test did you check the brake booster independently. I’d struggle to see it causing this much trouble but potential it has failed internally and only causes running issues due to pulling air into the system. You are on SD so again I don’t see that being likely but a smoke test or boost leak test wouldn’t show anything with the check valve in place on the booster vacuum line.

I have seen ethanol mess up injectors even if they are rated for Ethanol. One thing you could check is on the top of the injectors there may be SS filters/screens that may have corroded causing the injectors to not work as they should. This will cause the car to run sporadically.

A couple thoughts..

Yes the flex fuel sensor is a Cobb, i have not pulled the sensor, should i just unplug it the sensor and try running the car that way? I also didn't check the brake booster individually but i thought the car would lean out if it was a vacuum issue not die rich. These injectors are also brand new and have never had ethanol ran through them. The car is currently at the point where it will idle and start consistently it runs really rich (confirmed not the tune) checked my fpr and everything as well. The afr cor. and afr are perfect while the car is cold but as soon as the car warms up it runs at -25 afr cor. and like 13 afr. Then if i press the gas pedal the car will increase in rpm but as soon as i let of the car gets super rich and then dies because of to much fuel.

[Simply_Richard]

Update after reading some stuff online i am interested in trying to replace coolant temp sensor any objections to this?

[Simply_Richard]

Another update here, i vacuum tested the brake booster individually so i can rule that out also tested the check valve in the hose from brake booster to manifold and that is all good.

[BlackFighter]

Not sure if it was address before but do you have a light FW with a light crank pully by any chance? I had same issue when i put in a very light FW with a cheapy OBX light crank pully.