The throttle body on my TPI seems to stick when
the motor is warm(89 TPI IROC, w/ LB9/T5WC).
It sticks at different points (1500 - 2500 rpm). A gentle touch on the gas pedal returns the idle to normal (750 rpm). I've checked just about everything i can
think of for binding; accelerator cable, cruise cable, i've removed and cleaned the throttle body and checked for hindered mouvement of the throttle blades.

A friend of mine says it's comon problem,
has anyone had the problem and found a cure.

Thanks guys.

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Sat "IROCkid" Bimrah
1989 IROC-Z 5.0 L / 5 spd

 

89,

Misaligned throttle plates can get stuck in the bores at various locations. A worn throttle shaft or worn bushings can introduce some misalignment. Dirt in the bores can make the problem worse.

If you have disconnected the TPS and all cables and cleaned the unit with no success, you may be shopping for a new throttle body. If the cables are intact and operating smoothly, there isn't much left but the throttle body and return spring.

Check the throttle body for smooth operation. Clean the TB bores and IAC ports with a spray-type carburetor cleaner. Check the throttle operation by hand with the engine off to make sure it operates smoothly and returns to the idle position without binding. Look for polished areas around the throttle plates and bores where there might be interference. Open the throttle wide and try to move the throttle shaft up and down to check for excessive play.

A weak spring can cause poor return, but it's more likely that the shaft/bushings are worn. Unfortunately, unless you have a small lathe and mill, installing replacement bushings is not a fun chore. You could disassemble the TB, drill and ream for the next standard bronze insert, press in the inserts, then finish ream for the throttle shaft size, but you would still probably have some wear and clearance at the shaft itself.

A replacement throttle body may be the answer if you find yours worn, but make sure everything else is checked before you get out the plastic.

If you find the TB is operating corectly and is not excessively worn, you're back to the cables and TPS possibly binding the throttle shaft.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

I had a similar problem on my 87 tpi.. there is an unused post off the throttle body above where the accel cable attaches.. i went to a hardware store and bought a nice spring and put it from there to the cable mounting bracket that screws into the plenum just put it on and it works like a charm.. but now i'm replacing my TB so i should no longer need it.. hope it helps..