Rev Limiter ---help

Today was probably the first time I opened my boat up to see what she could do. Push the throttle way down and just to make sure nothing left I pushed to the floor and the RPMs actually dropped by about 200. I think I hit the rev limiter. After that, the boat ran around idle speeds like crap. A few times when changing out boarders, the engine would turn over and immediately die. When it did turn over and idle enough, I didn't wait and gave it some gas.

While I was getting the trailer for the boat, my wife was idling around the docks and the boat felt like it was missing and about to stall. When I got in the boat it was as if it was in Limp Mode. Also, not only did it feel like missing extremly bad, when in gear forward or reverse, the prop was barely turning enough to get me to the dock.

Last year when I was demo'ing my boat, afterwards my dealer said "they were hitting the rev limiter and it needed adjusted". Sounds like the same thing. Hopefully I can figure it out, but most likely I'll take the boat back to the dealer over an hour away.
Could it be the throttle and wires? Location in the throttle assembly or back in the engine compartment. Engine is Merc 330 Scorpion on my Centurion Avalanche. Prop and shaft are in perfect condition, that's not it. Thanks.

If it is hitting the rev limiter it would be that the wrong prop is on the boat. There is no adjustment for that. It should not run bad after it hits the rev limiter. The limmiter is RPM based so as long as you are under the uper rpm limit it should run just fine.

The dealer needs to check the computer for why it was running so bad at idle

(Message edited by krbaugh on June 14, 2008)

I have hit the rev limiter in my 06 tige due to a bent prop and it cuts in and out at high speed but runs fine once back at an idle. Is yours electronic throttle or cable. If it is cable something may have slipped causing a lower idle. Try adjusting the cable if you have one. mine is electronic when it messes up the boat goes to an idle and sounds an alarm telling me it has a problem. If I shut it off and restart it everything is good. My dealer is ordering me a new controler.

Joe, it sounds like a couple of bent valves. However that is really unlikely so you can let your heart go back to operating normally.
Most likely it's an electronic fault in a sensor, and is not likely caused by running on the rev limiter. With car engines I've used the rev limiter many times to avoid shifting gears for a couple seconds. There should never be a negative affect from the bumping the limiter.
On your engine the redline is 5200. Any rev limiter should kick in above that.
What RPM did the boat get to?

"Is yours electronic throttle or cable. If it is cable something may have slipped causing a lower idle."

I'm pretty sure I have a cable and that's where it slipped. That extra inch I pushed it to the floor probably loosened the screw that holds the cable and my dealer probably talked mumbo-jumbo to me since I'm not terribly good with engines other than an oil change.
The prop is stock upgraded for boarding and surfing so I just expect a low top end. 5200 is my limit and I was there. Effects were noticed at idle only.

I don't think I messed up the engine at all, but I do need an adjustment somewhere (my wife agrees there).

Thanks for the replies, I'm going to trace the throttle back to the engine to see if a wire is loose. If it was loose, it might explain why sometimes it may grab and give me throttle, other time so loose I can't get idle

his boat is running rough and your guess is bent valves? there is a ton of stuff that will make a boat run rough. joe i think i would try some other stuff before i pull the heads off. or pull them off whatever.

With the up grade wakeboard prop it would not surprise me if you hit the rev limit.
Something is wrong with the idle problem. I am pretty sure that the idle speed is set by the ecm.You do have a mechanical shift and throttle on a 2006 scorpion

My neighbor that works on his boat came over and believe we narrowed it down to the throttle cable where it connects to the engine might be broken as we were not sure if it's meant to separate like that or not? Threads on the wire right there at a Block on the wire---not sure if the threads are supposed to hold the wire to that block or not...

Neighbor thought it was the idle ECU. Between the two I'm pretty sure that's it. Going to water test it in a bit. There's a nob on the idle ECU to adjust the idle and I'm going to mess around there and watch the cable at different engagements of throttle.

Do you have perfectpass?
http://www.perfectpass.com/pp_support_figure_A.html

Just got back from the test run. I also got pulled over and safety checked....

I got it to happen again and it was after Perfect Pass. I shut the boat down and everything was fine (with Perfect pass Off). I couldn't get it to happen again with PP off.

I'll take a look at the link above. Wife says PP was sometimes not working that day. I thought she was just a terrible driver. THX

Just looked at the PP pictures Kevin gave a link for: http://www.perfectpass.com/pp_support_figure_C.html

On my post above when I said "Block on the wire" that was the Brass Hex in the picture and there was a gap in between the Hex and the 'L' Adapter.

Looks like I get to fiddle with PP and save a trip to the dealer. Thanks alot guys.

No problem use the link to Perfect pass they are VERY Helpful either by email or phone.

The other thing to remember don't go wot with perfect pass engaged



(Message edited by krbaugh on June 15, 2008)

would a loose knock sensor mess with the ECM like this?

I do not think it would mess with PP, but that could be a seperate issue...

Spoke with Perfect Pass people. I'm going to pull the fuse on the RPM Sensor and see what we come up with. He said the RPM sensor if a problem would just want to throttle-down, but wouldn't mess with the timing/knocking.

After thinking about it, PP might be throttling down; and the boat, sensing stall, idling up for a tug of war so to speak. Not sure if that would explain it missing/knocking so bad though???

I'll keep you all posted. I run PP via speed, not RPM so removing the sensor shouldn't change how we use PP.