TPS calibration

[aklackner]

Takeaway:
The OEM p73 ecu reads Throttle Position Sensor voltage from .5V Idle to 4.5V WOT. However if you’re using an OBD2 reader you’ll see absolute throttle position based on 0-5v. So you should read something like 10% as 0, and 90% as 100%. Yet some the ecu isn’t happy much above 8% more than that and the engine revs at idle.

So I’ve been chasing some issues on 010386.
Specifically I was facing surging under throttle and separately throttle was sticking a little open when heat soaked. (Say 30min drive)

Surging turned out to be a bad primary O2 sensor and is now resolved.

The I was running an Edelbrock GSR throttle body and throttle cable for simplicity with JRSC. This is a very old unit and I think it may need to be rebuilt leading to sticking issues so I swapped to a brand new Edelbrock ITR specific TB, throttle cable, and LHT throttle cable roller bracket. This was easy enough but couldn’t seem to get multiple position sensors to read 0-100% or 0-5v. Finally got the Absolute TP % PID on my obd2 reader to show 0% but then got a cel that tps was under voltage.

Pulled out the Helms and turns out despite that the pid was reading 0-5v the ecu needs the sensor between .5v-4.5v (0-100%).

This has potential to impact all sorts of data logging and analysis.