Hi guys
I have a problem with my Tib. I have a slightly fluctuating idle but if I rev the car to say 5000, the car stays there? The throttle body is working and I have tried 2 different TPS kefico and bosch. I can't figure out what is wrong? if I switch the car off and turn it back on it is fine. If I dosconnect the tps the revs drop back down and go back up when I reconnect but this happens with both TPS. So do I hve 2 bad TPS? Or maybe a vacuume leak or something?

Thanks in advance for any help

 

Could be a bad TPS, or you could have your idle adjusted too high or too low. The IAC is a tricky little buggy device that has alot of qwerks when you get into it's nitty gritty. Sometimes the IAC works counter intuitively.


Make your car idle at 800 rpm with the IAC disconnected and the A/C off. Adjust your RPMs at the throttle body. Once your car idles properly without the IAC, then connect it and see what happens after you reset the ECU.

The IAC may be dirty as well. Sea foam will clean it out. Then shoot some silicone lube in there to lubricate it back up. Not too much or you'll end up wetting the electronics.

When you let go of the gas, the car opens the IAC wide open to drop the rev slowly. It may be that it is sticking, or your idle is adjusted improperly.

 

check the spring on your tb,the butterfly may be sticking??

 

Thanks for the suggestions. I have checked the idle with the IAC on and off even with it disconnected the car is reving up and down at idle, I disconnected both the IAC and the TPS and it is still bubbling on the revs. I can't see a vacuume leak either. Could it be that I have 2 faulty TPS?

 

Could be. You recently do anything to the car?

 

If the TPS being disconnected doesn't change the symptoms, I'd say to try looking else where.

How is the FIC mapping looking these days? Did your computer lose its marbles maybe?

 

I took the supercharger off the car and I also disconnected the FIC.

The TPS and IAC didn't make any difference to the fluctuating idle.

Could the 1.8L cam be causing a fluctuating idle?

 

No. The cam will not affect running qualities in a notable fashion.

In your first post you said the behavior changed when the TPS was disconnected, then the next post seemed to contradict that. Could you please give a more detailed description of what exactly happens, with and without the TPS connected?

Yes you can have 2 bad TPSs. There are probably several hundred thousands of bad ones around the world.

You said that the throttle body is working, but how about the cable? If the throttle cable hangs/sticks, that might explain sticking at high engine speeds.

What have you done to check for vacuum leaks?

 

First of all, go to a local auto parts store and order a NEW TPS (if that doesn't fix the problem, just return it and say you didn't need it).

Check the TPS wiring harness (perform the "wiggle" test).

Do you have a 1.8 ECU in your car by any chance?

If you reset your ECU, will the car act normally for awhile afterwards?

Have you checked the throttle/cruise cables?

Do you have any CEL codes?

 

Thanks for the help guys

It turned out to be the idle adjusting screw. It was tightening itself when the car was reving high with the vibration hence causing the revs to stick. I have now removed the screw and everything is running perfectly.