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Old 10-30-2008, 03:46 PM   #151
Innovative Tuning
Former Vendor
Member#: 67958
Join Date: Aug 2004
Chapter/Region: Tri-State
MY96 Time Attack
and 06 STI daily


Originally Posted by Mechie3 View Post
Lastly is the secondary air pressure sensor signal (B134:27). This is the only item connected to the ECU that is interrupted when removing the valves. I need to play around with my valve a little bit, but my guess is that there are 2 options here:

1: Disconnecting this results in a CEL that we turn off.
2: We can bridge this wire to another with a resistor to fake the signal.

There's the problem. I don't know the function of the air pressure sensor, so I'm not sure what it should be bridged with.

Has anyone here been protuned without the airpump and without messing with the harnesses?

Unless I'm missing something, I don't see this interrupting anything except a secondary pressure sensor which, by the term secondary, is more than likely a backup. My guess is that people saw 1 part of the wiring (probably the schematic, which is confusing as all getout) and figured all of the sensor grounds were suddenly interrupted. The wiring diagram (which is a bit more common sense than the schematic to read) seems to show that that isn't true.
I just found this thread. Thanks for the kind words.
I didn't have much info when I sent you that e-mail other than seeing an ECU freak out with my own eyes simply due to the air pump being removed on another customer's car. It was adding a timing floor, making the minimum timing higher than what's prudent to run in the lower RPMs at high load.

That secondary sensor is the barometric pressure sensor, not a backup MAP sensor. That ground seems to be the one causing issues which make the ECU prescribe dangerous ignition timing. With that ground hooked up the car goes right back to normal. Before it was hooked back up I kept trying to remove timing from the ECU cal in various way and none of them did anything at all. Again, with that plug hooked back up, I could make adjustments and get the desired affect with no funny business.

I have a feeling the people not having issues are not unplugging that portion of the system:

You can isolate the ground wire and run it yourself if you don't want to keep that unit shown for clearance, like when you're putting a GT35R kit and a front mount IC on an 07 STi...
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