I just installed a new Professional Products 58mm TB on my heads/cam 350, now when the blades are closed, TPS at 0%, it idles very low, however, once driving, the throttle wants to stick around 10-12% open and I have to do a quick rev to bring the throttle back closed. When the engine is off there is no problem with the throttle returning to zero, but when engine is running, it wants to stick slightly open, DataMaster says 10-12%. What could cause this and how to fix?

I do plan on doing the 1/2" tube to the IAC port on the intake soon, but I don't see that causing the partially sticking open throttle?

 

Do you have ASR? I had the same issue with my '93 vette when installing a 58mm. It was the throttle cable sticking after I had ajusted it.

 

No traction control,

 

I've seen too many issues related to throttle position adjustment and sticking at various temperatures from the cheap cast throttle bodies. You cannot beat a billet cnc throttle body from TPIS. You get what you pay for.

 

Update: I guess these just have to "break-in", because other than the initial first drive with it last night, it ran fine the rest of the night and today it is running perfectly fine as well, no sticking, idle is normal.

I do love the quicker throttle response and what feels like more pull at high rpm's vs the stock 48mm TB.

 

Nice. Yeah maybe it was just a bit of a rough casting..

I always like to go over my TB's and port / polish them lightly. They are almost never perfect from the factory.

 

I had simular issues with my professional products TB. I simply adjusted the idle screw, which takes a few tries, to get my idle to hang around 11/1200 rpm when I'd push my clutch in. When I first installed it, it would hang around 1800 untill I came to a full stop then it would slowly drop to 850. All part of the aftermarket game.