Hi, I have a 1991 Firebird, 3.1L V6, auto tranny, 155k miles. My problem is that lately the car wants to idle very high, like 1500 to 2000 rpms. What will happen is that it will be fine (normal idle at 600) and then randomly the idle will shoot up. And the only way I've found to get it back down to where it's supposed to be is to disconnect the battery or pull the ECU fuse by the air cleaner. Once I do that, it will work fine for a day or two and then start the high idle again.
All the vacuum lines look good (replaced 3 years ago). Also, there is very little carbon build up in the IAC valve and throttle body. I used a scan tool and found that while the TPS sensor is showing a voltage of .58 (according to the manual that is in the closed throttle range), the computer says the throttle is 20% open, even though the throttle body is completely closed (I visually checked) and I am not stepping on the accelerator.
The plugs, wires, cap, and rotor are all brand new. And I replaced the computer with a rebuilt one and it is still doing it. Please help, it is so annoying to have to reset the computer every couple of days, and then have to deal with the car stalling and running awful while the computer is releaning. Thank you so much!
All the vacuum lines look good (replaced 3 years ago). Also, there is very little carbon build up in the IAC valve and throttle body. I used a scan tool and found that while the TPS sensor is showing a voltage of .58 (according to the manual that is in the closed throttle range), the computer says the throttle is 20% open, even though the throttle body is completely closed (I visually checked) and I am not stepping on the accelerator.
The plugs, wires, cap, and rotor are all brand new. And I replaced the computer with a rebuilt one and it is still doing it. Please help, it is so annoying to have to reset the computer every couple of days, and then have to deal with the car stalling and running awful while the computer is releaning. Thank you so much!
Aug 31, 2007 at 12:28 PM