TPS Eratic

[John 69 Camaro]

Hi,

I have an Edelbrock 3500 Pro-Flo EFI in a 383 Stroker. The optimal setting for the TPS is 13 degrees. The problem I am having is maintaining the 13 degree setting. It may be okay for days, weeks, or even a month or so, then it moves either upward or downward. I installed lock washers to ensure the bolts stay tight but that didn't solve the problem.

Has anyone experience this issue and if so, what was the fix.

Thanks, John

[DeltaT]

TPS may be bad and need replacement, but also check to see if your TPS uses a reference voltage and that all your engine/chassis/body grounds are in place and effective. If it does use a reference voltage, take a look at that when the TPS value changes for no reason - it might be a reference voltage issue.

Jim

[camcojb]

also make sure your throttle blades are closing completely without issue; too tight of a cable, kinked accelerator cable, something under the dash rubbing on the pedal, bad angles for the cable to throttle body or cable to pedal, etc. can all add just enough resistance to change how the blades close, and if they close completely. Of course any change there changes your tps voltage.

Jody

[John 69 Camaro]

I did some checking today and found my throttle rod connecting the throttle body to the gas pedal was a bit too long and it wasn't allowing the throttle blades to fully open. I shortened the rod and now both the primaries & secondaries open. I took it for a ride and the TPS at idle maintained 13 degrees. At WOT the TPS reads 84 degrees. I believe the optimal TPS reading at WOT is 90 degrees, so I either need a shorter throttle rod, increase my idle & readjust my TPS, or remove the insulation around the gas pedal to allow it to travel further. I'm leaning toward the latter because I think I have my target idle set pretty good at 1027 RPMs. This stuff is fun!