I hoping the new water pump is here tonday so I can get it put back in and start it up and put on the scanner later tonight. I'll try to get the hole print out and send it to you so you can take a look at it and see if you see anything. I'll do one with the motor warm and started and one with it warm and not running.

Well it ended up being the IAC Once I changed that out it ran great

What IAC did you get? Merc or auto version?

Mercrusier

Thanks. Just replaced mine with an auto one and we'll see how it hold up.....

That's what was in it that I just replaced it was put in back in 2013

I wish I could figure out who makes them for Merc anyways some of the auto cross overs do not do as well plus have different PWM % compared to what Merc uses. Some auto cross overs even after new install will have a slight rough idle.

The harder the IAC works the faster it fails and of course on some IAC failures it has knocked out the PCM. I probably see 1 per year on an average.

Merc IAC do not even come painted anymore they use to. Just saying.

Ran mine for the first time today after replacing IAC with a NAPA one and it was obvious the idle was too high, around 900rpm per tach. Even after it warmed up it around 850-875 again per tach. Had my scanner with me but never hocked it up. May scan it tomorrow to see the exact rpm. I saw your other post BUP on running the test so I don't have premature failure. ay do that tomorrow too. I know theres also a thread on here somewhere that talks about the high idle but haven't found that one yet. It may be buried in the same thread as where you talked about testing it..... In case I don't find it, what do you do if it idle is high? I know it's from the IAC so do I mess with the idle itself or swap out the IAC till I get one that has the proper idle setting?

i'm having similar issue as you vindicator101 on my port side motor. Did you ever resolve the high idle?

Hi yes I did it was the Idle air control valve.