I've been chasing a too-rich-at-idle condition on my 2056 D-Jet (rarely above 11.5 on AF mixture). I've previously changed out the TPS board and calibrated it, and I have a new wiring harness I installed in the spring. THIS THREAD got me thinking about it.

I understand the ECU goes into "idle" state when pins 12 and 17 are grounded, and then the mixture can be adjusted via the Pot knob on the ECU. To test this I removed the ECU connector and with throttle closed checked continuity at pins 12 and 17 on the connector. Nothing. Pushed down on the throttle to see if I could close it more, and thought maybe I was getting some connectivity. So then I checked continuity between pin 17 at ECU connection and at the wire terminal for 17 at the TPS connector. That was good. Tried connectivity between TPS terminal 12 (the middle wire on the connector) and ECU connection pin 12 and found nothing.

Am I checking this right? I assume there should be connectivity from the TPS wire connector (the middle wire on the connector) to Pin 12 on the ECU, right? I wonder if I have a wonky wire on that circuit.

At one point I tried the calibration method with the throttle body mounted and rotated the TPS switch clockwise while checking continuity between ECU pins 12 and 17, and at one point I thought I had it and tightened down the screws. Then it was gone.

Kicker is now my AEM Innovate wideband is crapping out and need to order new sensor. Car's running great, but I would like to get this resolved so I don't foul oil, plugs, etc.

And Jeff just corrected me that I should be checking pin 11. Thanks Jeff!