High Idle

[mdk681]

I had a strange thing happen last night after a night of surfing on my '99 21v. We fired up and ran over to the typical surf spot where we rode for a couple hours. After draining ballast we decided to head in for the night. After running at higher RPM's for about a minute I came off plane to head through a no wake channel. I noticed that my idle was significantly higher - instead of the typical 600 RPM's, I was around the 900 mark. It seemed to be running smoothly, but just higher than usual.

After I made it through the channel, I tried revving up the engine in neutral, putting it in reverse, etc. and saw no change. I pulled over to the side and shut it off to visually inspect the engine compartment. Nothing seemed out of place with the throttle cable. I fired it back up and it was back to normal. We ran at higher speed for a couple minutes then idled through a long no wake zone and the boat was normal from then on.

Seems like a freak occurance, but I am still curious as to what happened. Anyone see this happen before?

[whitlock87]

Is your engine a MPFI? (Fuel injection)
Your throttle body might have had a small piece of debris keeping it from closing all the way.
This will allow extra air into the intake which will cause the higher RPM

[mdk681]

Is your engine a MPFI? (Fuel injection)
Your throttle body might have had a small piece of debris keeping it from closing all the way.
This will allow extra air into the intake which will cause the higher RPM

I am very poor with engines, so bare with my lack of knowledge. It is the 350 MAG MPI Tournament Ski motor.

[boatwakes]

Your problem is the throttle position sensor, had it do the same thing to mine but I always bring my engine computer and found a shop nearby with the part. The part number you will need is 803148 and costs about $90. There are two torx head screws that hold the unit on. When you replace it, keep in mind you'll have to put the tps on and then turn into position as the base is spring loaded.

[whitlock87]

If the boat is running fine now, I would leave it alone unless the issue comes back.

It could be any number of things from the IAC to the TPS, but my dad always said if it’s not broke don’t fix it!

[mdk681]

If the boat is running fine now, I would leave it alone unless the issue comes back.

It could be any number of things from the IAC to the TPS, but my dad always said if it’s not broke don’t fix it!

That's what I was thinking. Hasn't happened since and I have about 7 or so hours tacked on already. Thanks for the advise, if I see it come back at last I will have some direction.