High idle at 1900 RPM. Otherwise good

[CaptainMak]

Replaced all my bellows this winter. Pulled engine to replace oil pan gasket and rear main seal.

When I started her back up again, the idle RPM was around 1900. It was nice and smooth idling, no shaking, sputtering, racing, etc. Just stayed at 1900.

Went to check the throttle cable. Seemed okay. Took it off, boat still idling at 1900 RPM.

What gives ? IAC, TP Sensor ? Engine is a 2001 5.0 EFI Alpha...

 

[CaptainMak]

Re: High idle at 1900 RPM. Otherwise good

Could last season's fuel also be the problem ?

 

[Volphin]

Re: High idle at 1900 RPM. Otherwise good

I'd be searching for a vacuum leak and checking the timing.

 

[alldodge]

Re: High idle at 1900 RPM. Otherwise good

+1 with Volphin, may have pulled a vacuum line loose when winterizing. If not that pull the IAC and IAC muffler in the throttle body

 

[CaptainMak]

Re: High idle at 1900 RPM. Otherwise good

I was wondering if anyone can help me out with this IAC valve.

When you unplug it while motor is idling, do your RPM change ?
Because when I unplug mine, nothing happens to idle speed.
Just to make sure, here's the pic of it. It's on the LEFT with 4 wires.

 

[Bt Doctur]

Re: High idle at 1900 RPM. Otherwise good

disconnect the throttle cable first at the TPS

 

[alldodge]

Re: High idle at 1900 RPM. Otherwise good

I was wondering if anyone can help me out with this IAC valve.

When you unplug it while motor is idling, do your RPM change ?
Because when I unplug mine, nothing happens to idle speed.
Just to make sure, here's the pic of it. It's on the LEFT with 4 wires.

View attachment 230544

I don't know of an IAC with a vacuum line, they have an electrical plug

Edit: the thing with the 4 wires coming out of it

 

[CaptainMak]

Re: High idle at 1900 RPM. Otherwise good

Not sure if it's a vacuum line, but I've seen some IAC VALVES with hose coming off it. If I take TPS connector off, engine starts shaking and runs rough. But doesn't stall

 

[Bt Doctur]

Re: High idle at 1900 RPM. Otherwise good

the cable not the connector .wondering if your linkage is giving you the rpms

 

[CaptainMak]

Re: High idle at 1900 RPM. Otherwise good

the cable not the connector .wondering if your linkage is giving you the rpms

Took the throttle cable off completely. Same high idle. Will replace the IAC today and see if that helps. If not that, I'll save the aggravation and cave in for the local shop here. :facepalm:

 

[alldodge]

Re: High idle at 1900 RPM. Otherwise good

Took the throttle cable off completely. Same high idle. Will replace the IAC today and see if that helps. If not that, I'll save the aggravation and cave in for the local shop here. :facepalm:

Suggest take it off and clean it with some carb cleaner before buying another

BTW, did you use the Merc engine rings to pull the engine or bolt the chain to another location? Also when pulling the engine did the chain rest against anything which may have been moved/bent?

 

[CaptainMak]

Re: High idle at 1900 RPM. Otherwise good

UPDATE*********

Went to NAPA and got a new IAC (idle air control) valve. $25 part # 3-1755.
Installed.

Motor started at about 1100 rpm for 10 seconds, then dropped to 750. Wohooo.

If it wasn't so early in the morning, I'd have a toast for all you guys that helped out.

 

[CaptainMak]

Re: High idle at 1900 RPM. Otherwise good

Been starting it all day on and off since about 9 am. Fires right up, idle at 650 stable. In FORWARD gear idle, 1100rpm. I'm sure it will be lower once in water.