'86 Firebird 2.8.
my tps wasn't giving me correct voltage numbers.. so bought a new one.. installed today .. was able to set voltage at closed throttle to 0.54 volts as I have read on this board.. but at WOT it's supposed to be over 4 volts.. or in the neighborhood of 4.75 volts... at WOT my new TPS only reads 3.15 volts??? as i measured the voltage and slowly opened the throttle, the voltage did increase smooth and linear as it's supposed to.. tried it several times.. only would go up to 3.15v. ?? Can anyone help with this? Would really appreciate it.

 

What is reference voltage ?

 

I'm not sure what that is.. the voltage before I plugged the 3-wire harness into the TPS was just about 5v.. is that what you mean?

 

Yes the gray wire is the reference voltage. Sound like the potentiometer has to high resistance is the old one faulty ?

 

not sure if old one is faulty, but it was giving me weird voltage readings.. i replaced it because i'm trying to fix a stumbling on acceleration problem which seemed to be the MAF, but I replaced the MAF (which didn't help), i replaced the IAC,, so now I'm trying the TPS.. even with all that it still stumbles on acceleration.. unless the I unplug the MAF so it reverts to speed-density mode (as I've read on here). then i don't have the problem of stumbling.. but with the MAF plugged in I have the problem.. and nothing else seems to affect it,, just the MAF, but it's a brand new ACDelco MAF and it didn't fix the issue either,, so I'm pretty lost here. and i do really appreciate you assisting me with this problem. Maybe you have some input about the MAF?? Thank you.

 

Just checked ref voltage at grey wire.. 5.00v. The middle wire (blue) at closed throttle is right on the money at 0.54v. But still only goes to 3.15v at WOT.
Also tested the old tps.. not attached to throttle body but just plugged into harness.. completely wide open only goes to 2.88v?? ..which is why I figured it was bad. So I'm still confused.. need more help.