Throttle Stuck Open At 12%

[RedTalon95]

Last night while driving home, I was about to get off at my exit and realized I was having a hard time slowing the car down. With my foot completely off the pedal the SAFC was reading 12.5% throttle. In neutral the car revs to 3.5k-4k. I managed to get the car home, but the throttle is still stuck open.

The cable has slack and the spring rotates all the way to the stop and back. The pedal also goes to the floor and comes completely back up. Has anyone had this problem before? If the spring rotates all the way around, does that mean the plate is getting completely closed, or could it still be physically stuck open even if the spring is in the closed position? If it isn't the plate being stuck open, what would cause this to happen, maybe a sensor or the ISC?

 

[JusMX141]

The TPS senses movement of the throttle plate....so even if the ISC was stuck open and causing the car to idle unusually high, the throttle plate would still be closed all the way and the TPS would read 0% position.

I'm not sure what would cause this unless the cable is unwinding inside the housing.

 

[RedTalon95]

Could it be a bad TPS?

 

[JusMX141]

Possibly, but a bad TPS shouldn't cause a high idle. I mean, even if the TPS was bad and said throttle was at 100%, if the throttle plate is closed, no air would be getting by to raise the idle.

Something's gotta be holding the throttle plate open....look at the throttle cable and cruise control cable (if it's still in place). If it's the cruise cable, you can easily eliminate cruise on a '95 without effecting the throttle control.

 

[RedTalon95]

Thanks for the replies.

The cruise has been removed and the throttle cable doesn't appear to be snagging anywhere. Could it be bad throttle body shaft seals causing enough air to come through or would that just cause a high idle? The car definitely doesn't just have high idle. If I put it in first gear off the gas pedal it would accelerate.

I guess I have to take the elbow off and have a look. I just assumed that if the spring rotated all the way to the stop, the plate would physically have to be completely closed.

 

[Auto RS T]

I also agree it sounds like the throttle plate is physically open somewhat.

When it is reving on its own can you pull the gas pedal up and lower the rpm? Go to the TB and try to close it by hand. Does the rpm change?

Check your floormat, and follow the throttle cable from start to finish, seeing if anything is pulling on it causing the throttle to crack.

 

[RedTalon95]

I also agree it sounds like the throttle plate is physically open somewhat.

When it is reving on its own can you pull the gas pedal up and lower the rpm? Go to the TB and try to close it by hand. Does the rpm change?

Check your floormat, and follow the throttle cable from start to finish, seeing if anything is pulling on it causing the throttle to crack.

The gas pedal goes to the floor without resistance and comes fully up. The throttle body spring is at the stop and can't go anymore. The cable has slack at the throttle body and isn't pulling on the spring.

 

[RedTalon95]

I've fixed the problem. Somehow (possibly due to the addition of new Prothane motor mounts), the SAS screw wiggled the nut lose and rattled into a difference position. A quick adjustment and it was back to normal.