TPS fault diagnosis test
 

Just made a backprobe test on my 1995 tps...

black voltmeter pointer on grey tps connector wire, red voltmeter pointer on battery terminal, key on

Reading is 0.01 and stay there, no move on...

Can we say it's time to replace it?

On your car the TPS is non adjustable, and the minimum is set by the ecm when you turn on the key...With key on the TPS should read around .6 volts, and while moving the lever to WOT the voltage should move up smoothly without any voltage drops up to around 4.5-4.6..If you meter isn't showing any movement , and the wires are hooked up right , then it's time to replace your TPS..:thumbs:....WW

First of all, I would say that I've made a mistake, chilton's manual say to read voltage at TPS connector blu wire not grey, so i need to came back to the car and make a new read

What chiltons says its a little bit strange....

"The voltage should read less than 0,5 volts"

I think with minimum open throttle it should be around 0,54V

The reason I'm not familiar with what wires to hook to is because I always set mine with a scanner...Scanners are quicker...:D...WW

PS...The .54 is for a L98 engine, the LT1 starts with a slightly different reading. You just want to have a smooth voltage progression with no dead spots or fluctuations as you move the throttle upward....WW

Well i've just made a read again, seems that there's a slightly voltage progression... But just from 0,60v to 4.13 or 4.64 don't remember right one...

Anyway there are two strange thing

No possibility to get it lower then 0,60v this is full unscrew TB screw...

It won't go over 4,64 v as higher voltage

What I'm searching for is the right voltage to set lt1 Tps via TB screw

If you have a 95 Corvette your TPS is "NOT" adjustable..You just screw it in and your finished...If your reading goes from .60 to 4.64 without the voltage dropping, then there's nothing wrong with your TPS......The only ones that are adjustable are on the older cars..You can screw the TB screw all day and it won't change the settings on the TPS..But you will mess up your idle adjustment...:banghead:... .WW

It's true that tos in not adjustable, infact in cannot rotate it when Installed on TB

THOUGH

screw on TB side moves shaft and blades as result it moves even tps on the other shaft side located

My problem is that screw was been messed

A normal multimeter is typically too slow to register a voltage drop off in some cases. While some multimeters might display the drop, I recommend a graphing meter.

https://www.corvetteforum.com/forums...lp-needed.html

here our friends mention about 0.64 v with minimum open throttle.

infact mine wont go under 0.6 v. but I can increase it a little bit tighting TB screw

You don't have to worry about if it's .6 or .64 or whatever as long as it's close, because the cars computer ( ECM) will figure out what your low reading is and will set it for you from there...Your making this much harder for yourself then it has to be....:willy:....WW

:iagree:

The PCM reads the TPS voltage when you turn on the ignition and saves that number and calls it "idle". It should be approximately 0.6 volts for non-adjustable TPS sensors.

Ok i've got it...

But what is the TB idle screw purpouse?i've heard many times that there's a plug on it, and is a good thing do not mees with it

Chris

The idle screw is to adjust the amount of air that the engine needs to work properly with the other components of the engine.. If you have moved the screw off of factory settings you would have to do a "minimum air adjustment" to get it back where it belongs...WW
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Yes I've done it,

do you know what need to do in order to get a minimum air adjustememt?

Thx my friend

I've already try to this some months ago, but my idle no go under 850-900rpm

It will if you turn the "idle" screw enough. As you take away the air, the idle speed has to slow down.

On my car this not happen
The reason is that at some point, TB shaft has a stop that is screw unconnected with it

So i can turn screw again and again but idle stay there.

This point that i would to call "zero" match 0,60v on TPS and 850-900 rpm

Either your throttle body is too dirty to allow the throttle blades to close all the way...

Or, you have a small vacuum leak somewhere causing the higher idle...

Or, your ECM is commanding the IAC open too far for some reason

Or, your IAC is not acting correctly.

All except the first are easy to spot with a good scan tool.

Those plugs on on the throttle body so people don't screw around with them trying to fix it the WRONG way. Not a dig at you but I've seen that before on GM throttle bodies.

Dumb question does it idle at that RPM ALL the time? A/C on and off? In gear and not in gear? Hot and cold?