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Old 01-15-2011, 05:40 PM   #1
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Default Strange TPS values when engine is running

I put a dial for my TPS on my tunerstudio dashboard today because I wasn't convinced my TPS is giving correct values.

Calibrated TPS.

Ignition on but engine off. Throttle closed 0%, Throttle Open 101%

Engine on. Throttle closed 10%, Throttle Open -22%???

Why would my TPS work fine with the engine off but as soon as it's running the values are all weird?
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Old 01-15-2011, 07:00 PM   #2
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do you have a vtps?
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Old 01-15-2011, 07:39 PM   #3
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Yes.

Tps & throttle body off a nb8. I can get full range values between 0-100% when engine isn't running.
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Old 01-15-2011, 09:30 PM   #4
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I think I had my TPS signal walking on me when I was experiencing bad grounds...or maybe a loss of the 5v ref signal. Check both of these.
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Old 03-21-2011, 01:41 AM   #5
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OK I seem to be having this issue too. I have a 3 wire vTPS off a 1.6 automatic, Wiring is correct.

Calibrating in TS is no problem. Ignition on, engine off, TPS sweeps from 0-100% without any issue, as seen here.
Name:  tpscal3.jpg
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Engine on, signal is a bit jumpy and goes from a low of -30 to about 50-60% max. Checked calibration of zero throttle in TS, no change in value.


I measured the voltages at the wires with the engine off and on.

5v reference: engine off zero throttle: 4.96 engine off full throttle 4.97
engine on zero throttle: 4.96 engine on full throttle 5.00
TPS signal: engine off zero throttle: 0.65 engine off full throttle 1.99
engine on zero throttle: 0.65 engine on full throttle 1.20

Why do I have a drop in voltage at the TPS signal wire when the car is on?

Can anyone guide me on the steps I need to do? I did try running a new wire for the TPS signal and ran it straight to the 2L pin. Same thing.
Is it a ground issue? If so, how do I track it down?

Thanks MT

Last edited by Greg G; 03-21-2011 at 01:58 AM.
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