Project Miata Update

I spent all day Saturday stripping a wiring harness from a junkyard Honda Pilot to get some quality OEM wire and then running a new TPS ground wire from my sensor to my ECU analog sensor ground. I didn’t want to drill any new holes in my firewall and there wasn’t enough room to run it through the same hole as my vacuum reference hose. So I did what many others have done and just poked a tiny hole in the large rubber boot that seals the hole where the vast majority of OEM wires pass through the firewall to the ECU. It’s not pretty but it gets the job done. One day I’d love to shave the engine bay and do a custom wire tuck and motorsports harness with high end connectors. But for now I just want the car to run!

Unfortunately, the wiring change did not result in a significant improvement in the level of TPS noise. So my choices now are either to live with it (and a TPS averaging lag factor of 30) or completely rewire the TPS using shielded wire. If I rewire then I will probably just get rid of the vacuum line I’m not using now (it was a major pain to run through the firewall and I was saving it for a potential switch to ITB Load Mode down the road) and just run the shielded wire through there and make the necessary changes on the ECU connector. Does anyone know how to de-pin wires at the OEM ECU connector?


Also, the Auto-zero TPS function doesn’t seem to work for me as I still get occasional negative TPS values if I calibrate the sensor normally. So instead I have to manually overshoot the “Closed throttle ADC count” so I don’t go negative as the ECU doesn’t know what to do with negative TPS values.

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