2016 Mercruiser 4.5l Shift Interrupt switch

[phil chieco]

Hello, I recently purchased a 2016 Hurricane deck boat with the new 4.5L Mercruiser engine. I have had several occasions where the engine has stalled when coming into dock.. This is certainly annoying and has been sometimes dangerous if not for my passengers stopping the boat from hitting. It seems to be an intermittently problem and happens when either slowing down from forward to reverse or just slowing the boat down to almost neutral. It's also happened from going from reverse to forward. The boat would completely stall and I would get a series of beeps and it would take about 10 - 30 seconds to reset itself so I could restart. My question is, could this be related to the Shift Interrupt switch and is this something I can adjust? Any assistance would be appreciated on how to adjust this properly.

 

[alldodge]

My question is, could this be related to the Shift Interrupt switch and is this something I can adjust?

It could, and it is adjustable
Could also be the IAC is starting to stick/fail. Is the idle smooth and at what RPM, and when it doesn't stall does the RPM stay steady?

 

[phil chieco]

Thank you for responding so quickly. For the most part, the idle appears to be smooth. However I did noticed a couple of times recently when cruising slowly just off of idle, the engine seemed to be a little erratic meaning it would speed up and slow down subtly and did not hold steady at that position on the throttle. It cleared up as soon as I gave a bit more throttle. Again I was still going extremely slow. I can take the boat out this evening and monitor the idle more closely. I would guess it idles at 600 - 700 rpms but will confirm. What is the IAC?

 

[phil chieco]

It could, and it is adjustable
Could also be the IAC is starting to stick/fail. Is the idle smooth and at what RPM, and when it doesn't stall does the RPM stay steady?

Thank you for responding so quickly. For the most part, the idle appears to be smooth. However I did noticed a couple of times recently when cruising slowly just off of idle, the engine seemed to be a little erratic meaning it would speed up and slow down subtly and did not hold steady at that position on the throttle. It cleared up as soon as I gave a bit more throttle. Again I was still going extremely slow. I can take the boat out this evening and monitor the idle more closely. I would guess it idles at 600 - 700 rpms but will confirm. What is the IAC?

 

[alldodge]

Idle Air Control valve.
Its what the computer ECM uses to control idle rpm. It can get gummed up or just go bad. Doesn't happen often but can happen.

If it goes out completely you have to give it throttle or it will die

 

[phil chieco]

Idle Air Control valve.
Its what the computer ECM uses to control idle rpm. It can get gummed up or just go bad. Doesn't happen often but can happen.

If it goes out completely you have to give it throttle or it will die

Do you by chance have a diagram of where it's located and whether or not it could be tested. Also could it be the shift interrupter switch and can I adjust that.

 

[alldodge]

What is the motor serial number?

 

[phil chieco]

Idle Air Control valve.
Its what the computer ECM uses to control idle rpm. It can get gummed up or just go bad. Doesn't happen often but can happen.

If it goes out completely you have to give it throttle or it will die

Hello, Do you have any instructions on where this is located as well as how to test it or just replace it. Thank you

 

[alldodge]

What is the motor serial number?

Again need motor serial number

 

[phil chieco]

What is the motor serial number?

Please see attached. Thank you

 

[alldodge]

Tx 2A455891
Looks like you have digital control, so drive by wire. The IAC is part of the throttle body (item 10). The bad news is its not serviceable and expensive

Your motor uses load anticipation (don't remember if that's the right term) which means the throttle is placed at a given RPM and then the PCM will adjust power to keep it at that RPM. Conventional throttle being moved to a certain position and if the load increases or decreases you would have to give more or less throttle.

Need to get the motor scanned in real time to see what is happening. Need Diacom software or Merc dealer G3

https://www.mercruiserparts.com/bam/subassembly/31525/16591/100

 

[phil chieco]

Tx 2A455891
Looks like you have digital control, so drive by wire. The IAC is part of the throttle body (item 10). The bad news is its not serviceable and expensive

Your motor uses load anticipation (don't remember if that's the right term) which means the throttle is placed at a given RPM and then the PCM will adjust power to keep it at that RPM. Conventional throttle being moved to a certain position and if the load increases or decreases you would have to give more or less throttle.

Need to get the motor scanned in real time to see what is happening. Need Diacom software or Merc dealer G3

https://www.mercruiserparts.com/bam/subassembly/31525/16591/100

Tx 2A455891
Looks like you have digital control, so drive by wire. The IAC is part of the throttle body (item 10). The bad news is its not serviceable and expensive

Your motor uses load anticipation (don't remember if that's the right term) which means the throttle is placed at a given RPM and then the PCM will adjust power to keep it at that RPM. Conventional throttle being moved to a certain position and if the load increases or decreases you would have to give more or less throttle.

Need to get the motor scanned in real time to see what is happening. Need Diacom software or Merc dealer G3

https://www.mercruiserparts.com/bam/subassembly/31525/16591/100

Thanks for your assistance. For now I'll use it through the rest of the season because it's very intermittent. However when I pull it out I guess I'll bring it to my local dealer and have them scan it.

 

[alldodge]

Thought of something else, because it will die when shifting.
Happening while shifting might be the shift interruptor switch (item 18) seeing you have a Alpha drive. The switch is used for a split second each time when shifting out of gear (FWD to neutral or REV to neutral). The switch causes the motor to misfire to unload the clutch in the drive so it will release

Look and see if the switch contact is dead center in the middle of item 3 when in neutral, and will also stay centered when in FWD/REV

https://www.mercruiserparts.com/bam/subassembly/31525/16591/300

 

[QBhoy]

Hi. The most obvious reason for this would be bad fuel or clogged filter perhaps. Do you have smart craft gauges or vessel view mobile installed ? A shift interruption error would come up on these. Like mine below