Well i recently switched TB and im having trouble with a high idle.

When i first start the car the idle seems ok, it starts high and then drops down. Looking at my datamaster it starts out about 70 when the motor is warm but it will steadily drop until it gets to zero. It will idle fine untill i touch the gas, then it will carry a high idle at 1500-2000 rpm. If i let the car sit for long enought it will drop to about 1200, somtimes get as low as 1000. Idle is set for 875

The throttle blades are closed and i can find any vacume leaks, i sprayed carb cleaner at every vacume line i could find and the idle never changed.


The TPS volts are .55.


Any ideas, the IAC sensor was fine on my stock TB, and i had my friends 52mm with his own sensors on my car and it worked fine.

 

OK, i found a vacume leak and fixed it, the idle is back to how it usually is but the IAC step is still going back to zero. I guess the car has been idling just a little bit high, like 100-200 rpm and ive never noticed it?

Is the IAC bad?

 

You probably need to adjust the blades on the new TB you swapped on via throttle stop. Odds are that the throttle stop was in a different position from your old TB and the blades are cracked open a bit more than your old TB, letting in more air and causing the IAC to drive shut in order to maintain the commanded idle. This is provided that there are no more vacuum leaks.

 

The blades on the TB are closed, i already tried adjusting the throttle stop, its all the way backed out.

I think i am going to go buy a bunchg of vacume line and replace it all. Looks like some of it is starting to crack and get dried out.