Mechanics

WHAT WOULD MAKE MY TIBURAN IDLE SPEED FLUCTUATE FROM 800 RPMS TO 4000 RPMS.

2003 Hyundai Tuscon • 118,000 miles

I installed a used 5 speed transmission in my tiburon and when I first started it the idle problem was there, it was fine when I started the trans. Replacement, I had replaced the tach/speedometer gear and sensor in the replacement tran. With the one from my old tran. Also I had the ignition switch on when I hooked up the battery post. Would a surge from hooking up the battery mess up a sensor that controls idle? Any help would be greatly appreciated.
Avatar
Ex3200
July 8, 2012.



It probably would not affect the Idle Air Control Valve which is a servo that controls idle. It would more likely mess up the ECU if you had the harness hooked up, but then you would more than likely have other issues. I would check for vacuum leaks especially around EGR at exhaust.
To help here is a walk through diagnostic for your situation. I think pulling the trouble codes will be important. Any Advance Auto or Auto Zone will do this for free. You do not have to have a check engine light to have a trouble code present which would really help eliminate a lot of possibilities.
Just use the link below;

http://www.2carpros.com/articles/engine-idles-too-high

Try this one to;

http://www.2carpros.com/articles/engine-surges