TPS readings

[clickittyclank]

1987 GMC Sierra Classic - 350 TBI

Testing on the TPS sensor and not sure what the verdict is on it. When testing the TPS manually with a volt meter and pushing the arm back with a screwdriver I get the full .5-4-5v range. However, if I use the throttle lever the TPS reading tops out at 3v. Mine seems to be the non-adjustable version so I'm thinking the TPS is worn out and not moving at the correct pace but wanted to make sure before I swap it.

I had another one on there before that was stuck at full throttle and giving me a code 21. With a little contact cleaner and dielectric grease on the arm I got it working again but no idea for how long. Both of these have some age on them but thinking if the cleaning/lubing brings the other one back around I'll swap it back in and call it good.

Appreciate any help.

 

[YakkoWarner]

Sometimes on the non-adjustable ones you can use a needlenose plier and bend the little arm that the throttle mechanism pushes on to get the readings in range. When you only get 3V at wide open, are you still reading 0.5 at full closed? If you tweak the arm to get 4.5 at wide open, you may find yourself with 1.5 or so full closed which is also not going to work well.

I had to use the tweak the arm technique because one of the screws broke off in my rebuilt throttle body (before I ever even got to start it once), so I only have screw and a stub now, which means its now a non-adjustable but tweaking the arm got it to go 0.47 to 4.3.

 

[clickittyclank]

Yeah it was .5 at closed. Hoping this other one holds up in its refreshed state but if not may tinker with that arm and see what the readings change to.

Those little screws are in a wonky spot unless you don’t have or remove the egr solenoid bracketry. Looks like these got replaced with some flathead screws/bolts back in day so even wonkier now haha.