i have an obd1 D15 in my 88 HF. i used the obd0 injectors, alternator, and distributer. i have a 90 SI ecu running it.

the problem is it has a surging idle. The IAC valve is unplugged because if its plugged in, the idle goes to about 4 K when i start it up, then drops to a surging idle. what could be causing this? vacum leak? timing? i'm clueless. the car is also throwing a code for the O2 sesor. its running rich, but i can deal with it running really rich, and i dont think thats the cause of my idle problems.

please help, i need an answer fast, this is getting real annoying

 

bump

 

put a new iacv on it , and check all your gaskets for leaks . mainly the t/b gasket and intake gasket

 

a mechanic that lives across the street today said it was the timing. i dunno if hes right or not... any more suggestions?

 

Take off your intake tube and put your finger over the hole inside of the throttle body to close it off from the IAC and if that fixes the problem then it is your IAC. You can always make a gasket to put between it and the throttle body to close off the flow for a temporary fix.