Mystery Electrical Issue - Sends into limp mode after hitting large wave

[huntwerner]

Need some help with a mysterious issue I’ve been having for a few years which is getting worse. When we hit a wave hard the boat will go into what I think is limp mode. Engine does not cut off, just goes into idle and will not go any faster. Can turn the boat off and back on and runs fine. It has been progressive worse over the last two years. My thought is that it’s a loose ground but was talking to someone who mentioned it could be a bad knock or temp or oil pressure sensor. Suggestions of where to start? Thanks

[ScooterMcgavin]

Welcome to the forum, what model and year is the boat? What engine does it have?

[huntwerner]

It is a 2006 Air Nautique SV - 211 TE with a PMC Excalibur 330.

[jkallen21]

I think I know what your issue is - I hope so anyway. Disconnect the battery. Remove the kick panel at the driver feet. Look for the red and black wires that power the panel. I don;t have pics but it should be obvious. They are held on with copper/brass nuts - hopefully they are still there. Tighten them up and that's it. If that is not it, perhaps its the bilge switch under the dash - try lightly pounding the area around that while you're slowly underway. That switch has been known to go bad and cause similar issues.

[NautiqueJeff]

What you're describing is not limp mode. Limp mode will limit you to 2500 RPM's, but not just idle speed.

Is the big red light on the dash on? If not, that's not limp mode.

I would guess you might have a throttle position sensor issue.

[jkallen21]

It’s funny - I believe Jeff told me the exact same hint about it not being limp mode years ago and that’s what guided me to look elsewhere. I eventually found it by running the engine and stomping all around the boat and it happened most near the kick panel. I also replaced the potentiometer with no luck along the way.

[SkiLakeCav]

jkallen21 - I'm having this issue on my 2006 with a 330 excalibur, as well. Changing the throttle position sensor and throttle body didn't work for me either. I haven't had a chance to check the battery cables behind the kick panel, though that's next on my list. You also mentioned a bad bilge switch could cause this issue. Do you know why that is?

[jkallen21]

I don't know what the switch is actually called but “Bilge switch” is not the words I should have used. It's the 3-position switch under the dash (bilge only, all off, all on). My theory was that if this switch is loose, it would cause the engine to rapidly go off/on which causes this issue that's a lot like limp mode.

Iā€™m curious what your kick panel looks like though. Be sure and disconnect the battery first because if the wires are loose they could touch anything back there. Mine was an 06 too but ZR6.

[jmo]

If the connection to the 3 position toggle/kill switch is the issue, it would result in a complete loss of power when it glitches and you would have to restart the boat, hence I think your issue lies elsewhere. I had the blade connector on the back of my kill switch come loose after removing the kick panel to do helm work and I forgot to put the screws back in to hold the panel in place. I then trailered it 3 hours at the start of a vacation where with the panel moving around it caused the loose connection. This resulted in no power to the dash, once I tightened it all up I was good to go.

[SkiLakeCav]

Circling back here as I believe I've solved the throttle issue on my boat. I recently replaced the TCP to TAC Jumper wiring harness (PCM Part # R121086) and have not had the issue since.

I went down this route since the issue was temporarily fixed whenever I would unplug and replug the ends of this wiring harness. Simply turning off and turning back on the engine was working less and less. When I plugged in the ends of the new harness into the TCP and TAC, the connections felt significantly more snug, almost to suggest there was a loose/poor connection on the older wiring harness.

The part was approx $60 and took seconds to replace. It ultimately could have been the combination of the new throttle body, TCP, and this new wiring harness. However, this new harness was apparently the missing piece. Definitely a simple and relatively cheap solution that I'd recommend crossing off the list before moving on to more expensive components.

Now just hoping it continues to hold up.

[jkallen21]

Great info - can you say where this harness is located for future readers?