Hey, folks...

If you have a scantool that can show the voltage of your TPS, how many volts do you read when you are applying zero throttle (and while you're at it, WOT, too?)

Here's why I ask... my '87 GT (47,000 miles) has a habit of hesitating when I apply only very little throttle (like, just enough to begin rolling). It will hesitate for about1 second, and then run perfectly. I have not read the voltage via my scantool yet (I was noticing this problem on the way into work this morning and my scantool is in my wife's van), but I am curious to see what voltage everyone else has.

The hesitation feels as if my foot has moved the throttle plate, but the ECM has no idea that anything has changed, so it hesitates a second until it can adjust the fuel delivery to match this sudden "vacuum leak" from the throttle plate moving. This leads me to beleive that the TPS may have a "dead" spot in it, or is reporting a voltage that is just too low for the ECM to accurately gauge.

Does that make sense?

Yes, it could very well be your tps, but I'd check the map sensor voltage too. The tps volts should be less than 1v at idle and over 4v WOT. What you want to look at is a slowly increasing voltage as you depress the gas pedal. Any jumps forward or backward would indicate a bad tps.

Phil

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86 GT TTops, 3.4 Auto.....bought from Doug of Fiero Warehouse

GM auto tech for 27 years. Specializing in electrical and computer problems. I will never be able to return as an auto tech again. I get EXTREME satisfaction helping others and will go to Extreme levels to help you if you need help. I have LOTS of free time on my hands. This forum and the help I give, allow me to have a purposeful life. Bring on the problems......LOL.

quote Originally posted by VoicesInMyHead: Hey, folks... If you have a scantool that can show the voltage of your TPS, how many volts do you read when you are applying zero throttle (and while you're at it, WOT, too?) Here's why I ask... my '87 GT (47,000 miles) has a habit of hesitating when I apply only very little throttle (like, just enough to begin rolling). It will hesitate for about1 second, and then run perfectly. I have not read the voltage via my scantool yet (I was noticing this problem on the way into work this morning and my scantool is in my wife's van), but I am curious to see what voltage everyone else has. The hesitation feels as if my foot has moved the throttle plate, but the ECM has no idea that anything has changed, so it hesitates a second until it can adjust the fuel delivery to match this sudden "vacuum leak" from the throttle plate moving. This leads me to beleive that the TPS may have a "dead" spot in it, or is reporting a voltage that is just too low for the ECM to accurately gauge. Does that make sense?

The TPS voltage varies with each engine ( or if someone screwed with the throttle plate stop screw). Manual says .60 to 1.1 at closed throttle and as the Dude said >4v at WOT. Make sure when you hook up the scan tool to get a closed voltage reading and it should increase smoothly as you depress the throttle. Also they don't always go back to the same EXACT voltage when you release the throttle. Check the MAP also as the Dude says. Also if you ever take the TPS off you must reset the ECM..........Paul

Just use an analog meter to test it using Ohms. If it jumps around when you SLOWLY move it it may be damaged or just dirty.

Thanks, folks.

I'll check it out.