92 MS3X with erratic TPS when engine is running
 

Hello All,
I just completed my MS3X build from Frank's instructions and the car (mostly stock 1992 with 1.8BP) starts and runs (a bit rough and stumbles). Before i actually started the car i went through the calibration requirements. I calibrated all the sensors to include the Wells 201TPS (Mod installed), stock CLT, GM IAT, and LC-1. Then is set the timing to ten degrees. All though i was actually getting a solid dual indication of 8 and 10 degrees with the timing light. I know i am at least close since switching back to the ignition tables, puts the timing at 22.8 degrees of advance at idle. Now to the actual problem the TPS. The TPS appears to work correctly when the engine is off (sweeps 0-100% smoothly as throttle is applied.) When you start the Engine the TPS signal fluctuates between -2 to -66.4% during idle. The TPS only reacts when you apply over 50% throttle, but even then the TPS% on tuner studio is very erratic and never stays within 40% of where the throttle is actually at.
So far i have verified the wiring to the TPS: TPS sig (main 22/2L), GND (main 2/2D), and 5VREF (main 26/1N). I am not sure where to go from here.
I will unplug the TPS tomorrow and see i can get it to run better. I need to get the registered version of tuner studio as well. But i would like to have the car at least idle well first.
Hopefully someone else has seen this issue, or know what went wrong. I have attached a data log. Hopefully this helps

Seems like ground noise. You can splice in a temporary wire and ground it to a clean area of the engine (you'll have to look up the sensor ground points for the 1.6L, I know its different than the 1.8) and see if that corrects the issue. If it does, you can come up with a more permanent solution.

go back and double check your wiring, to both the harness and tps.

Ok, Status update. The wiring is intact. I double checked it from ECU plug to the sensor connection. Then I checked the 5VDC and discovered 11.7 VDC. Slightly under battery voltage. Sensor ground .2 ohms and TPS signal had .792 VDC all while disconnected from the TPS sensor at the connection. I verified the measurements from the ECU connection (probed from the back of the connector). So I guess there is a failure on the U5 voltage regulating circuit. I will trouble shoot this. Again thank you for all the responses. I will report back when I make progress on this problem.

EDIT: I found the problem! I wired the 5VREF to pin 26 on the expansion board, when it really belongs on the main board. Doh!
Well now i can run the extra wires for the sequential injection and ignition and finally install the Toyota COP's i got from Andrew a few years back. lol