Hey Everyone,

I am at a loss with setting my TPS voltage. I have read through posts on here, over at thirdgen and others.

The car is a 1980 Camaro, with an '86 Corvette TPI

I tested my TPS voltage at WOT (between the top and middle wire), and came up with 3.85v. From what I have read it is supposed to be over 4. At idle, it is at .54, from again, what I have read, is correct.

I thought maybe it was the TPS itself, so I bought another, but it's the same thing. I tested the voltage between the middle and bottom pin, and got 5v. Again, within spec. I did a full sweep of both TPS's and they went all the way to 4.8v. Neither of them were jumping around while doing this.

I do not believe that the TPS is at fault. I test by manually operating the throttle body, and have confirmed that it does open all the way. Both manually, and with the pedal.

I am at an absolute loss as to where to go from here. I can get it above 4v, but my idle voltage is way too high.

Is something messed up with the throttle body? Is there something simple that I overlooked? Any help would be greatly appreciated. I want to get the car on the road soon, but from what I have read, if the TPS doesn't go above 4v, it doesn't go into "power enrichment mode" or something like that, and am not producing as much power as I can, because the car doesn't think it's at WOT.

I have seen posts where people have gotten it over 4.5v at WOT, im so confused!

If you need clarification on anything, please ask.

Thanks!

 

What year TPI and is it 350 or 305? Is TPS adjustable or non adjustable type? If it's adjustable, try backing TPS to .50. Do you have a scanner? if so what are your IAC counts?

 

It is a 350 from an '86 Vette. I do not have a scanner. I have had the idle setting from .4 to .7 or so. It doesn't really change the WOT reading though which confuses me. Since it sweeps from idle, to WOT, whatever changes at idle should be the exact same at WOT. But it doesn't seem to be the case. I'm very confused.

Thanks for the reply!

 

Lossen the tpi sensor and wiggle it to start fresh , set it to .54 and id tighten carefully . Recheck that it is at .54 then work the throttle to wot the voltage should rise steadily to 4.0 or so. If it doesn't check your wires since you say your tpi sensor is new. Actually to get it to read higher you would have to undscrew your idle screw so you start lower. But in order to do that we do a full minimum idle adjust to make sure the start point is correct.
Good Luck

 

I second the reset of the idle screw. Without knowing the IAC counts, you might be a bit off. When I got the corvette and reset the idle the end result was a full two turns of the screw. Run through these instructions:

https://www.corvetteforum.com/forums...dle-speed.html

I want to emphasize an important part:

Also, be careful with those TPS screws! As much fun as it was for me to drill out the old screw and get a brand new one, I'm sure you'd rather not do the same. :-)

 

Maybe I did not catch it, but what is wrong with the car?

 

The value "over 4" is an Internet legend. There is no place in the FSM that says that. Looking at the ECM code, it converts the TPS voltage into percentage. Anything over 70% is considered to be WOT. That works out to 3.5 volts, so the 4 volt number is bogus.

 

get an ac delco tps...theyre the only ones that ive had luck with. Car was a dog before, screamed afterwards.

 

So, then my 3.8v reading is sufficient. I just want to make sure that I am getting all that I can outta this engine. Thanks for the reply.

 

I did redo the idle during all of this as well. However, I just ordered a new IAC, because they're relatively inexpensive, and all the parts are over 30 years old now. I'll also give the TB a good cleaning.

Thanks for the info!

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