So I completed the throttle body coolant bypass mod this past weekend. Everything went well. Drove the car Sunday. Drove the car Monday. Car drives just fine both days. Yesterday I go to start my car and it's idling high, like around 1500 rpms. Usually it's around 800. I have a Scanmaster installed and it shows my throttle position percentage at 1.8 with the throttle blades closed. If I'm not mistaken this should be 0 when throttle blades fully closed.

Does this sound like a throttle position sensor issue? I don't own a voltmeter to check it, but I can get one. I just thought I'd see if others have ever experienced this issue.

Thanks for your help in advance.

 

sounds like a small vacuum leak. Check for cracked or unplugged vacuum lines. A vacuum gauge would tell you too.

 

Did you have the TB off or take any of it apart? Does Scanmaster ever show the TB at 0%, like key on, engine not running and blades closed?

 

The Scanmaster is capable of reading both the TPS volts and the TPS % (TPP). The TPS volts should be between 0.20 - 0.90 volts with the throttle closed. That will produce a 0% TPP reading.

 

I didn't remove the throttle body. I didn't plug the coolant inlet and outlet on the throttle body either. It ran fine without those being plugged all last weekend when I did the bypass mod and ran fine Monday. The next day, high idle issues.

Scanmaster shows 1.84 TPS voltage and 27 throttle position percentage. Both readings were with the throttle blades fully closed.

 

Have you checked to see if there is something mechanically holding the blades open? Have you taken the throttle and cruise cables off to see if the blades shut? Simply doing the TB bypass should not have bothered the TPS, unless you physically altered something when doing it. Are your TPS screws secure? Was it bumped or pried against during your work?

 

Problem solved. It was the TPS. Swapped it out and all is well. Thanks for everyone's help and input. I'm not used to fiddling with computer controlled cars lol