[castle_Rock]

Ok, A friend told me that perhaps the TPS is or has failed, causing the van to think that the pedal is floored.

By Quote:

"I had a similar issue awhile back with an old Buick. Complaint was long drawn out shifting and trans suddenly dropping out of overdrive and into 3rd at highway speeds and banging into gear. It turned out to be a TPS that was faulty and suddenly maxing out at 4.9v"

And he said every time the TPS spiked, the trans would downshift because the computer thought the driver was flooring the accelerator. It was also causing the trans to delay shifting.

My question is whats the best way to check to see if it is the TPS is faulty, maybe this will clear ALOT up.

 

[astro355]

If you have a scan tool, you can monitor the TPS output voltage.

If you don't have a scan tool, get a multimeter and back probe the signal wire. You can monitor the voltage that way also. I don't know which wire it is off the top of my head.

 

[castle_Rock]

Thanks Astro, I'll use a Multimeter and report the voltage.

Recently I checked for any codes, and only had the code 12, so it seems like the van is healthy, just needs performance upgrades.

 

[castle_Rock]

I just checked the voltage of the TPS, and received a voltage of 50. It doesn't show that the TPS could be maxed out. - this could be a good thing, but was hoping it would clear the shifting issues up if this was the case.

I tried removing the Bolts from the differential plate and it is super corroded. I sprayed it with WD-40 and tried to scrub it with an wire brush as well, hasn't made much difference.

 

[astro355]

50 volts? It shouldn't be that high. Did you use back probes and measure in parallel for the voltage? Or did you wire the multimeter in series?

 

[castle_Rock]

sorry, I didn't add the decimal, its .50 volts, I used a 7 function digital multimeter, and was using the 2000k scale, and tested the connector (the middle lead and the end lead), I'm not sure where the plunger is on the sensor, so the reading was solely based on the connector. is there a way i can adjust the TPS even if its not faulty, since this is only thing I can think of that may be causing the harsh shifting?

 

[astro355]

No, there is no adjustment to the TPS. So it measured 500 millivolts regardless of the position of the throttle blade?

 

[castle_Rock]

Yes. Since the Computer is not showing any codes, I am wondering if its more fuel than Exhaust issues thats causing these issues, as far as acceleration, it sounds like fuel, maybe its lacking, but am not sure. I dont care about the shifting, but the very slow acceleration is getting to me. What is the recommended PSI for a 94 Safari?

 

[astro355]

If the TPS voltage never changes from 500 milliVolts regardless if its at idle or wide open throttle, then that is your problem (or a problem). That voltage is supposed to change depending on the position of the throttle blade.