help with idle/throttle (TPI)

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Jan 31, 2005 | 08:30 AM

BlackC6LS3

Thread Starter

Melting Slicks

Joined: Nov 2003

Posts: 2,679

Likes: 1

From: South Amboy NJ

help with idle/throttle (TPI)

I know this is CF.com but the car is a TPI and many of you are very knowledgable about them so i figure you guys can help.

I bought an 88 gta, 305tpi, 5spd yesterday. While driving it i have noticed that the throttle hangs sometimes (the revs stay up). The gas pedal isn't sticking and the idle itself sometimes drops to ~600-800rpm, but sometimes stays up around 1500-2250rpm. The previous owner said they replaced some relays and tightened the throttle body screws that attach it to the intake. Any ideas are welcome. This is my daily driver and so i need to fix it asap.

Thanks in advance,

Dave

Jan 31, 2005 | 08:56 AM

comp

Team Owner

Joined: Sep 2003

Posts: 88,393

Likes: 2

From: eville in

look at and feel everything, has it been lubed when it was worked on ??

Jan 31, 2005 | 10:19 AM

WNDOPDLR

Burning Brakes

Joined: Apr 2004

Posts: 792

Likes: 1

From: Stanfield NC

First check inside the drivers cpmpartments and make sure your problem isn't with the pedal or linkage. disconnect the throttle cable at the carb and make sure the cable is free. If all is OK you may want to check the IAC which is a small piston/seat on the underside of the TB. These get carboned up and can cause erratic ideling. If that is the case, clean both the piston and the seat with carb cleaner and mild abrasive like steel wool. Doo not use emory paper or you may ruiin the seat. Go to this site for detailed instructions: www.geocities.com/jgkov/tpsservice.

Glad to help. Shear the knowledge.

Jan 31, 2005 | 10:48 AM

CFI-EFI

Race Director

Joined: Sep 2000

Posts: 17,298

Likes: 33

From: The Top of Utah

Quote:

Originally Posted by BlackRoseLT1

I know this is CF.com but the car is a TPI and many of you are very knowledgable about them so i figure you guys can help.

If you don't find any outside interference or binding, chances are that the bore in the TB that the throttle shaft turns in, is worn. Sometimes they only stick when the engine is running, due to air flow and pressure of the passing air. There are shops that will bush and seal those shaft holes, otherwise it's time for a new TB. Originally, the shaft just runs against the pot metal of the TB casting.

RACE ON!!!

Last edited by CFI-EFI; Jan 31, 2005 at 10:53 AM.

Jan 31, 2005 | 11:05 AM

lildrgn

Intermediate

Joined: May 2004

Posts: 46

Likes: 0

From: Huntsville AL

How long does the throttle stay up? Is it like driving, release gas/hit clutch/ slight rise in RPM while shifting?

Does the idle jump when just sitting around after warm up?

Im working on a Honda right now that does that. Found he was getting coolant into one of the cylinders causing it to just act funny.
Ofcourse, my Honda does that and it was just a vacuum line that had come out.

Jan 31, 2005 | 02:05 PM

BlackC6LS3

Thread Starter

Melting Slicks

Joined: Nov 2003

Posts: 2,679

Likes: 1

From: South Amboy NJ

i have a whole spare TPI set up but i don't wanna go replacing everything piece by piece. The idle sticks after the car has been reved up; it doesn't go up alone. The IAC was also replaced.