IAC Valve Calibration

[Gizmo99]

I just replaced the IAC valve on my stbd 07 DF175. I know the original was bad because I swapped it out with the port motor IAC valve and now the port motor is running good but the stbd is not. Anyway, the stbd motor has the new IAC valve and is running but idling at 1000rpm.
I have read that new valve may need to be calibrated. I looked through the service manual but I couldn't find a calibration procedure.
Does anybody know if this procedure is in the manual or how to do it?

[artdf175]

Page 2-16 of the service manual idle speed

[Gizmo99]

Thank you Art. I completely overlooked that.
So just to clarify, in the step 8 notes it says to perform the ignition key operation while the engine is running at idle. So, basically try to start the engine while it's running 5 times within 10 seconds. I just really hate the sound of the starter hitting a spinning flywheel.

[artdf175]

I hear you but you don't have to hold it until the starter engages
I think the ECM just needs a signal to be generated

[Murray]

Shouldn't the ECU recognize the engine is running and not allow the starter to engage?

[Gizmo99]

I gave this a shot this morning but didn't have time to finish the process before work.
The ECU does let the starter engage on my engines. It would make sense that it prohibit it though.
I started the engine and after about 20-30 seconds the intermittent alarm sounded like it says in the manual. I didn't perform the ignition key operation so I am wondering if the ECU sensed the new IAC valve and put it into fixed mode automatically. Anyway, I will go through the whole process tonight.

Thanks for the help guys.

[redlowrey]

Thank you Art. I completely overlooked that.
So just to clarify, in the step 8 notes it says to perform the ignition key operation while the engine is running at idle. So, basically try to start the engine while it's running 5 times within 10 seconds. I just really hate the sound of the starter hitting a spinning flywheel.

'''' If your starter motor is engaging the ring gear with the engine running you must have the early soft ware system, because the late system allows you to turn the key to the start position with the engine running, the ecu senses the tack signal when the engine is running and won't apply a ground the the starter relay when the key is turned to the start position.

[Gizmo99]

Update:
Went through the process of resetting the idle speed according to the manual. I did notice that it let me turn the key without engaging the ring gear. However, the alarm didnt sound for about 30 seconds though, and it will start to sound after 30 seconds of running even if I dont turn the ignition key.

I tried to screw in the idle adjustment screw clockwise but it went about 1/4 turn and bottomed out. I tried to back it out and go back in but it went to the same rpm.

I thought the new IAC may have been faulty so I swapped the valve out on the motors. I put the new valve on the port motor and its idles correctly as it did with the older functioning valve. (FYI the old faulty valve didnt pass the resistance test outline in the manual). I put the older valve on the stbd motor and the high idle issue persisted. Now the stbd motor has its original valve on it but idles high no matter which valve is on it.

I tried checking vacuum lines they all seem good. My only other thoughts could be the cable linkage is stuck or out of alignment, I did put some lithium grease on the cable heads during all this. I also have my engines hooked up via NMEA to my Lowrance MFD. This caused issues in the past with a bad NMEA 2000 connector. I will disconnect it tonight to see if that could be the issue. I was using that hook up to accurately sync the rpm to both motors though.

Im stuck again.....

[Gizmo99]

I think I found the source of the high idle. The gasket between the intake manifold shells blew out in one of the corners near the fuel vapor separator. I had forgot that there was back fire right after I installed the IAC valve. I guess it blew the gasket out. Zuke dealer here says the rubber gaskets are reusable which I guess is good because it looks the seal isn't sold outside of the whole assembly. Funny, because the service manual says to replace the gasket.

[Sushiseeker]

Hey Gizmo,

Did re-installing the Intake manifold gasket solve your high idle problem?

I had a backfire and have the same blown out gasket.

Thanks in advance,