5.7 L 350 MPI IAC, 2004 22V

[bsmithuw]

I did a search for IAC valve and noticed there have been a ton of threads about it. I'm sorry for adding another one.
My boat runs great when I'm moving, but sometimes at idle it dies, sometimes it doesn't. Very frustrating.
After reading the other posts, it seems I should change or clean the IAC valve. Does that sound right?
My boat also has a very loud air sucking sound so I suspect I'm missing the IAC muffler too.
Thanks for the help!!

[mjsti]

Yeah, the IAC valve can be cleaned with some carb cleaner if its sticking. Just remove from the engine, careful not to damage the gasket, and wash it good with carb cleaner to free up the movement. This may clear up your idle issue. Others with more experience than I may chime in on other suggestions.

Regarding the IAC muffler, if the loud sucking sound is at idle then you're missing the muffler. Its a cheap part, more than likely to pay 3X for shipping than the part itself. However, its a night and day difference with the noise. Money well spent!

[bobbysky]

I just had a problem with my idle as well. I removed the IAC and cleaned it and it didn't help my problem. My problem was on the initial start up it would fire up but go way low on the rpm's (400) then either die or surge up and down till it finally idled. Mine ended up being the muffler that is in the throttle body. It was completely gunked up and not allowing enough air through at idle. My redneck solution was to rip the green part off of a kitchen sponge and jam it down there as a new muffler. Low and behold it's worked perfect all summer long. So it's worth a shot to check that too.

[bsmithuw]

Also, I read on another site that the Smartcraft would beep twice repeatedly if the IAC was bad. Is this true? I haven't heard any beeps.

[strohlde]

If it is the IAC just get a whole new throttle body. Every part on Marine Power engines just costs more and are harder to find, the IAC alone is $305. I bought a new throttle body (including IAC) for $390 last year, and if I recall I think I bought it directly from Marine Power.

[bsmithuw]

I have the Mercruiser Mag 350. I can buy the IAC for less than $100, but I'll explore getting a new throttle body.

If it is the IAC just get a whole new throttle body. Every part on Marine Power engines just costs more and are harder to find, the IAC alone is $305. I bought a new throttle body (including IAC) for $390 last year, and if I recall I think I bought it directly from Marine Power.

[strohlde]

I have the Mercruiser Mag 350. I can buy the IAC for less than $100, but I'll explore getting a new throttle body.

Mercruiser parts are cheaper, probably just the IAC in your case. My mechanic just suggested for the extra $80 to buy the whole throttle body.