Low TPS Voltage

I took my 95 SC out with my scantool hooked up yesterday to check some things out and noticed TPS voltage was 4.5 at full WOT. Went full WOT 3-4 times with the same results, 4.5 volts. When I got home I turned the engine off and with the ignition on and gas peddle to the floor I get 4.4 volts. So I get out and fully open the throttle body by hand and get 4.7 volts which is what it should be at full WOT. About ten months ago I installed a Magnum Powers 85mm throttle body but before that I had a BBK 75mm TB on it and it always read 4.7 volts at full WOT so it's probably been low every since the 85mm install. My 94 SC with a 70mm BBK has always shown 4.7 volts at full WOT as well. I know I need to figure out whats going on and correct it but my question is would the low tbs voltage have any affect on performance. I have noticed my 95 feeling a little sluggish when getting into the throttle lately.

Have you confirmed the throttle plate is 100% open when you press the pedal inside?

Might be worth it to have a helper investigate so you can be sure this isn't contributing to whatever...

KMT said:

Have you confirmed the throttle plate is 100% open when you press the pedal inside?

Might be worth it to have a helper investigate so you can be sure this isn't contributing to whatever...

Click to expand...

No, I haven't confirmed the throttle plate is 100% open with the peedle to the floor yet but I'll be checking it out. Another thing I noticed is TPS voltage is .8 at closed throttle and I bellieve the consensus is it should be .9 at closed throttle. What I really want to know is will a low TPS voltage at full WOT have a negative affect on full throttle performance.

When attempting to service and/or diagnose a TPS, it can be important to remember that the communication back to the EEC is based on a range from a base value.

The base value can vary slightly and not be of (primary) concern as long as the range (base vs. peak) is within spec.

Do a search here for TPS set or calibration and review previous discussions, etc. to learn more...it has been covered in glorious detail, I'm sure