TPS calibration problem with DIYPNP
#1
TPS calibration problem with DIYPNP
Hello,
I've put together my DIYPNP and it bench-tests OK, flashes firmware, loads base map without issue.
But when I plug it into the car (1994) and I try to calibrate the TPS, I just get a static value of about 1023 regardless of the throttle position.
I have 5v between ground and the TPS point on the main board, and 0v
between TPS and VREF. That is irrespective of throttle position. I know the TPS itself to be functional.
What have I done wrong?
I've put together my DIYPNP and it bench-tests OK, flashes firmware, loads base map without issue.
But when I plug it into the car (1994) and I try to calibrate the TPS, I just get a static value of about 1023 regardless of the throttle position.
I have 5v between ground and the TPS point on the main board, and 0v
between TPS and VREF. That is irrespective of throttle position. I know the TPS itself to be functional.
What have I done wrong?
#10
Is there a good test procedure for the sensor? I get continuity between the bottom two pins with the throttle closed, and lose it with the throttle cracked slightly open. The top two pins have a variable resistance that depends on the throttle position. That seems pretty normal, right?
Also, I didn't have any drivability issues with the stock ECU. Wouldn't I have noticed something if the TPS was bad? I am not exactly sure what the stock ECU does with that information.
Incidentally, both fans also turn on with the key. I'm not sure why that is. Doesn't seem likely that it would be related, though.
#11
Looking at the wiring diagram, the TPS seems to be OK. The switch switches, and the rheostat, uh, rheostats. So I have two places to go from here: there's some problem with the wiring between the TPS and the ECU, or there's something with the MS that is shorting the TPS to 5V.
The logical next step seems to be replacing the stock ECU and seeing if I get the same 5V on TPS regardless of throttle position.
The logical next step seems to be replacing the stock ECU and seeing if I get the same 5V on TPS regardless of throttle position.
#14
Here's what happens with the MS powered up on the bench and TunerStudio running. The reading just keeps climbing.
But when I try to measure the voltage difference between ground and the TPS pad, the signal drops to zero and stays there until I remove the probe.
How is that possible? How can it tell? Aren't multimeters supposed to have virtually infinite resistance in volt mode?
But when I try to measure the voltage difference between ground and the TPS pad, the signal drops to zero and stays there until I remove the probe.
How is that possible? How can it tell? Aren't multimeters supposed to have virtually infinite resistance in volt mode?
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Zaphod
MEGAsquirt
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10-26-2018 11:00 PM