TPS low WOT voltage

[6gunn]

I installed a new TPS and can get the max idle setting to .040. The WOT voltage will only go to 1.95v. It is getting 5v and the ground is fine. The WOT voltage with the old TPS behaved the same way, but the idle is much better with the new TPS. Any ideas why it's only showing 1.95v WOT?

 

[earlbrown]

You either have two bad TPSs or your 5v signal is dropping at WOT.

 

[6gunn]

You either have two bad TPSs or your 5v signal is dropping at WOT.

I put the positive lead of the VM on the 5v wire(grey wire) and held the throttle WOT. The voltage held steady at 5.05v. Would a voltage drop only occur with the motor running?

What's the TPS brand of choice of everyone here?

 

[6gunn]

Got another TPS (BWD from orileys) and it goes to 2.5v WOT now. This code 22 was the only code in the computer. Any ideas what I could try next?

 

[TurboDave]

To adjust the TPS for max WOT voltage, loosen both screws and push/pull the tps assembly as far forward as it will go, then thighten both screws just enough to hold it in place. To then adjust the idle tps voltage, keep the bottom screw lightly tightned, and loosen the top one enough to allow slight movement of the front of the switch up or down to obtain proper idle value.

 

[6gunn]

Even with the TPS rocked all the way back(top is far back and bottom is far forward) the idle voltage will only go to 0.25. If I press down on the TPS lever to make it read 0.40v, the idle is up around 1800rpm...and this is with the idle screw backed all the way off.Also took the TPS off the TB but kept it plugged in and moved the little lever as far as it would go. It still only went to 2.5v.

BTW, when I first checked the idle voltage on the original TPS, it was 0.16. This was before I touched anything.

 

[TurboDave]

You're getting all wrapped around the axle adjusting things the wrong way and making too many adjustments, and doing them wrong to begin with. Why did you rock the tps nose so far up? If anything is should be just a little above horizontal, and pushed forward. And you don't want to mess with the idle bleed screw (NO it's NOT an idle rpm adjustment!!) until you get the tps where you want it.
When and ONLY when the tps values are correct do you want to mess with the IAC screw, and to two have to be tweaked together.

How are you measuring the voltage values at the tps. Where's the + lead and where's the - lead?

 

[6gunn]

You're getting all wrapped around the axle adjusting things the wrong way and making too many adjustments, and doing them wrong to begin with. Why did you rock the tps nose so far up? If anything is should be just a little above horizontal, and pushed forward. And you don't want to mess with the idle bleed screw (NO it's NOT an idle rpm adjustment!!) until you get the tps where you want it.
When and ONLY when the tps values are correct do you want to mess with the IAC screw, and to two have to be tweaked together.

How are you measuring the voltage values at the tps. Where's the + lead and where's the - lead?

A little concerned about this, and it's frustrating to not get any results after 2 TPS swaps. Ok, I'll breathe and calm down.

I rocked the nose so far up because the voltage was no where near 0.42 when it was sitting horizontal. Rocking it up increased the voltage but would still only reach .25v.

The + lead is stuck in the blue(middle) wire. The - lead is stuck in the black(bottom) wire.

Thanks for the help.

 

[TurboDave]

A little concerned about this, and it's frustrating to not get any results after 2 TPS swaps. Ok, I'll breathe and calm down.

I rocked the nose so far up because the voltage was no where near 0.42 when it was sitting horizontal. Rocking it up increased the voltage but would still only reach .25v.

The + lead is stuck in the blue(middle) wire. The - lead is stuck in the black(bottom) wire.

Thanks for the help.

What are you measuring from black to gray? key on.

 

[earlbrown]

If you hold the TPS in your hand and can't get 4V, you either have a bad signal wire or a bad TPS.

Take your TPS, plug it up but don't mount it. probe the output, and actuate the lever by hand... If you have 5V going in, and less than 4V coming out, you have a bad TPS.

Take the TPS off the car and set your meter to Ohms. probe the resistance between the prongs for blue and gray and write that down. Then actuate the lever to the WOT position and write down that number. The second number should almost be a direct short.

When you go back to the parts house, test the new one at WOT and see the ohm reading is numerically lower.

 

[6gunn]

What are you measuring from black to gray? key on.

5.05v

Also should mention that I have a Powelogger but no scanmaster. Will hook up the laptop in a sec and see what it shows for TPS voltage.

 

[6gunn]

If you hold the TPS in your hand and can't get 4V, you either have a bad signal wire or a bad TPS.

Can I temporarily run a new wire from the TPS signal(blue) to the proper pin on the computer to rule out a bad signal wire or would this cause problems for other sensors that use the same wire?

Take your TPS, plug it up but don't mount it. probe the output, and actuate the lever by hand... If you have 5V going in, and less than 4V coming out, you have a bad TPS.

Did that and the max voltage it would show was 2.50v

Take the TPS off the car and set your meter to Ohms. probe the resistance between the prongs for blue and gray and write that down. Then actuate the lever to the WOT position and write down that number. The second number should almost be a direct short.

I will do this once I get a new VM. Tried to measure resistance and it's not liking it.

When you go back to the parts house, test the new one at WOT and see the ohm reading is numerically lower.[/quote]

 

[earlbrown]

Take your TPS, plug it up but don't mount it. probe the output, and actuate the lever by hand... If you have 5V going in, and less than 4V coming out, you have a bad TPS.

Did that and the max voltage it would show was 2.50v

...and at that exact moment in time was the input wire showing 5V? If so, the TPS is bad

 

[6gunn]

It was a bad Voltmeter!!! What a relief! It showed up in Powerlogger. Here's a log of the idle numbers. Note: The huge TPS voltage spike and no RPM increase around 20 seconds was done by pushing the lever down all the way to see WOT voltage. Seems it's not good to go over 4.8v so I'll adjust that later. Also have the WG solinoid removed but guess it'll have to be reconnected to get rid of the code 31. Thanks Earl and Dave!

 

[earlbrown]

So your voltmeter read 5V on the signal line but wouldn't read 4.5V on the output because the meter was bad?

 

[6gunn]

I know...it's strange. Guess it'll remain a mystery. When I went to check the resistance, it flashed the battery light. Replaced it even though it had a good charge...and the new battery did the same thing. Some weird noises came from the little speaker when I wiggled the battery connection. Anywho, the car is running so much better and code 22 is gone. Got the IAC count to 52, idle at 750-800rpm, TPS to 0.42v idle and 3.65v WOT.

 

[earlbrown]

Open the throttle blade a little more and get this IAC number down a little. (don't forget to reset the TPS after you move the blade)