I read the "Whipple 500 efi" thread but did not find what i was looking for, I have a 2000 502 Mag, side mount Whipple still running the original MEFI 1 and Whipple piggyback computer. Had an idle issue at the end of last season. The IAC was replaced and the idle was good at original throttle up but then would not back down below about 1200 rpm. Boat was winterized and stored for the winter. Still having problems this season, timing was off and has been set to 8 degrees per whipple and Merc spec. its always been cold natured but it will nowl idle about 900 rpm for a while but will die as soon as i shift into gear. I have to keep the rpm about 1000 while idling in gear and even then it will serge and then bog down and die and it can be hard to restart. Could the IAC be bad or is there some way to reset it after it was replaced? If a vacuum leak is suspected where should i start to look? I need to get this fixed docking is impossible!!

Did you replace IAC with the same exact one? They are NOT all the same!

Not sure i did not replace it myself, the work was done by an OSO Sponsor engine builder who I have 100% confidence in but i guess mistakes could happen. He did not have an extra in his shop so he pulled one from another engine he was building so he could get me back on the water. How would i determine the corrrect IAC i need?

Try removing the iac filter and see if it works correctly. They get clogged up and don't flow enough air. Wash it with carb cleaner. I've found that to be a problem several times on the side mount whipples.

Bob
Full Throttle Marine

Thanks I will check it but it was replaced with a new one last labor day same time as the IAC probably does not have 30 hours of run time on it.

You can run it without the filter. Take it out and see what happens.