08-05-2011, 08:58 AM
Join Date: Nov 2010
Total Cats: 0
VTPS, IAC, and Wiring questions
I have a TEC-2 standalone controlling my 1.6L miata with a 1.6 Auto throttle body. Currently the IAC is controlled by the factory ECU, everything else (fuel/spark/O2, etc) is controlled by the TEC-2.
I had originally wired the TPS into the factory harness as such:
Manual < -> Auto
black/green < -> black/green
red < -> green/red
green/white < -> red
Tec-2 TPS < -> red/black wire
Where the left column is the factory harness and the right side was the sensor side of the wiring.
Admittedly this wasn't right and not providing me good resolution as the TEC-2 would show between 0-1.6v output from closed to WOT. So working through the factory manual and using a 5V output from the tec-2 we provided 5v, ground, and VTPS signal to the tec-2 and cut the OE ECU out of the loop.
Initially this worked great, and TPS was good. However now when starting the car, it will start and die at any attempt to idle. My question is this: If the factory ECU doesn't see a TPS signal on startup, will the IAC act erratically? This car was running fine, no map changes, it has just gotten progressively worse the more I've driven it since the change. I can put it back to the prior wiring but wanted to get it "right".
tldr: Changed TPS wiring, factory ecu doesn't see TPS, will this cause IAC issues?