575SCi
 

New this year
When I put it in gear it almost dies but recovers and idles fine
When I put it back to neutral it revs up a bit then stabilizes back to a good idle. Just like an initial fast idle start.
Both engines are doing it. Each engine has two IAC's.
My first thought is the IAC's. What kind of number should they be at while idling in N and F/R. Next time out I'll plug the scanner in.
.030 pistons and 525ish roller cam if it makes a difference. Stock ECU's.

Mine did that with the AZSM tune. Eddie Young retuned as part of another project, and they idle perfect now.

Send them out and get them tuned or have it done in the boat

Any other changes Rob, or just a random glitch? If you run dual IAC's, one of them may have crapped out? You could unplug one at a time to isolate.

It was hot that day and I was waiting 2 hours at the locks so it might just be related to that. Forgot about it by the time I got back to Coulon and can't remember if it did it there or not. Next time out I'll bring the puter.

theres a little brass looking filter on the IAC housing that can get dirty and clogged. You could check that, hit it with some brake cleaner.

Actually, that day sucked. Left Coulon to cut, 15 minutes, idled 45 minutes to locks, waited for 3 hours to get through, 5 minutes to get to Edmonds. Moored and walked around for a couple hours, left Edmonds for locks, 5 minutes, waited 2 hours to get through, idled 45 minutes through cut, 15 minutes back to Coulon. But heck, I have a nice sunburn!

I gotta figure out how to convince Tracy that new props will resolve the issue.

Got some numbers port / star
fuel flow @ idle in N 2.7 / 2.7
fuel flow @ idle in F 2.9 / 3.0
injector on time in N 2.1 / 2.1
injector on time in F 2.3 / 2.3
IAC follower in N and F 0 / 0
base IAC in N 7 / 10
base IAC in F 70 / 72
IAC position in N 5 / 10
IAC position in F 70 / 72
baro 30.3
manifold 13.7
MAP @ idle V 1.96
throttle % 0
TPS @ idle .45
air temp F 82
engine temp F 143

The port engine is the one that feels loaded, like it has a larger prop. The RPMs and throttles are in the same position at all speeds so the props are true.
As I shift, the IAC,s go high then settle at the numbers posted.

If I've been running, come off plane to idle, let it stabilize, and shift to N, is when it feels like I've just taken a huge load off the engine the most. The idle jumps to about 1100 then settles back down. Port side only.
As I maneuver for docking it doesn't do the above but it does bring the RPM's down to about 500 every time I go into gear, then stabilizes at 750. Port side only.

Based on the numbers, your thoughts.

We talked a little about this on the water, Post #4 still is what I feel. I have a couple spare IAC's if you want to swap one out-

I'm thinking they're sticky and slow to respond. The numbers are close enough that I think they aren't plugged, just slow to get where they need to be. I don't want to break the paint if I don't have to. I've got spares on the engine next to it. One good thing about twins! I'll get them swapped over before I go out again.