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Old 06-05-2013, 04:24 PM   #39
Scooby Specialist
Member#: 224449
Join Date: Sep 2009
Chapter/Region: VIC
2012 Kit B STI
Midnight ???


For those that know but are not sure about the problem.

Stumble Fix under acceleration for GR/GV STI

Disclaimer: This is more than clicking your seatbelt or resetting your ECU, it may permanently damage your engine or fueling system if done incorrectly.

This is the most prevalent issue with GR/GV STI's, our fueling system creates a water hammer pulsing effect which makes the car run lean and stumble from 2.4k-3.1k RPM (vehicle specific) during a light/WOT acceleration. For those that use OST, you may also notice your check engine light comes on if you cruise between 2.8k-3k RPM in 6th gear more than a few minutes with the code being P0171 of "Lean on Bank 1/2" or P0296 "Post catalyst fuel trim system too lean" . This will also fix that issue.

By lengthening our fuel line, it disrupts the pulse in the loop, creating a much smoother fuel delivery to the engine.

This guy will do a much better job at explaining than I ever will, pictures included.

Tested Compatibility
- MY09 STI
- MY10 STI
- MY12 STI w/ SPT Package

Worked for 3 cars, all with the same effect of fixing the stumble.
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Last edited by belaud; 06-05-2013 at 05:29 PM.
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