TPS calibration
Posted: Tue Feb 06, 2024 7:28 pm
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.
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.