First post, Hi all, 88 iroc 350 TPI. Rebuilt the engine , all fine ,now after about 2000 miles, engine runs withn a rough idle and no low end power. OK after you get to about 2000rpm. But shakes rattles in idle in drive really bad. Been reading the boards for a week and have changed relays, cap, plugs, wires, coil module, roter... still no relief. checked timing set to at 6btdc then reconnected everything a bit better but still lags. Tommorrow will change the IAC and the fuel filter see if that helps. any suggestions

 

Bob,

Welcome Aboard!

Instead of changing the IAC, you could try cleaning and lightly lubricating it. They really don't fail that often except due to dirt. Unfortunately, the IAC typically doesn't afect the idle quality, only idle speed. Unless the idle is excessively low (500 RPM or less) the idle should be relatively smooth.

You've eveidently covered the ignition system pretty thoroughly, so you may want to take a closer look at some of the other possibilities. Cylinder compression is easy to check, and can affect the idle quality significantly. Then there is the fuel delivery. A power balance test of the injectors might be pretty revealing.

 

how would a home mechanic check "A power balance test of the injectors might be pretty revealing"????

 

Hey, I cleaned the IAC and put a new fuel filter in, Rechecked the timing all much better, Im going to check compression today, try to find someone who knows about the injection to check that Thanks for the help and Im sure ill be back later for more info. thanks Vader. Bob