575sci High Idle Question....
 

Two weeks in a row I had the same intermittent problem with my port side motor. The motor runs fine while running hard......then I come off plane to a idle speed.....as soon as I put the shifters in to neutral the port side motor jumps up to about 1800-2000 rpm and stays there.......won't come down at all. I shut the motor down and idle on the starbord engine for a minute or two, start back up the port motor and it is ok but seems to surge from 800 to 1200 rpm..... Now I know IAC is gonna come up as a possible problem but I installed a new IAC in the beginnig of this season............what else should I be looking in to................................

Try swaping IAC. Let us know if problem stays on same motor.

Do you have twin IAC motors or just one?

I have to check .....

I have seen several of these do that its been the tps sticking. they are easy to replace.

A friend of mine also mentioned the TPS so I ordered one this morning....... thanks so far guys I will let you know if any of these fixes the problem.........

How about checking the value of the IAC. It should be at about 15.
Just because it is new doesn't mean the setting is correct.

Also check TPS, but I'll bet that is ok.

Check the seat where the IAC seals. Sometimes you will get carbon built up and it will prevent the IAC from seating all the way. Use some carb cleaner and get rid of the carbon. Those engines run a little rich so they are real susceptable to carbon build up in the throttle body and intake. Hope this helps,Eddie.

according to my serial # (0M052321) I only have one IAC.....


http://www.mercruiserparts.com/Show_...ody+Components

Didn't think of this......I will check this too Eddie.......Thanks..