My son and myself installed a 87 305 MAF TPI on an 86 305 El Camino. We have managed to get everyting to work correctly except the idle speed. No matter how the idle adjustment and tps is set it will return to a fast idle (1500 rpm) when the engine is restarted. The min idle adjustment looks good and the engine runs very smooth during this setup. All sensors are new, all seem to work correctly and no codes are present. Does anyone have any experience with this or know where to look? Thanks, Dave

 

my solution was to unplug IAC and idle never above 900rpm. Every time i adjusted IAC it would run real good but after restarting it would idle at 2500rpm. Something in the computer is wrong or some sensor is missing. I also found that when my motor heats up one of the blades would get stuck unclosed making idle 300 rpm's higher when warm.

 

did you put the tpi on your car or did it come with it? do you know where the timing is? i also noticed that the timing is at 30 deg when you restart. i tried to adjust it back and also unpluging the advance and it did bring the idle speed down but you lost advance with it therefor loosing performance. Do you know where the timing should be at idle with the advance pluged up? if you unplug the iac will you not have problems with idle being smooth when the ac comes on and off? Do you have a program or know of one that will allow you to see the actuals and targets at the same time? that would at least let you know if it is doing what it is being told to do.

 

If you've properly adjusted timing, the IAC and TPS, look for a vacuum leak. I had a 2000 rpm idle after incorrectly installing SLP runners. Once corrected, the engine idled properly.

 

If the timing advance and IAC are unpluged, you can adjust the TPS and low idel screw and get the idle you are looking for. What should the idle timing be with the advance pluged up?