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idle speed too high


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Idle speed is not really adjustable on EFI engines. It is controlled by an idle air controll motor (IAC) which regulates how much air to let passed the throttle body and the ECM then matches that with gas from the fuel injectors. The IAC is pretty dependable, so I would look for other ways air is getting into your engine intake area. First make sure your throttle plate is fully closed when throttle is at idle speed. Then look for vacuum leaks, loose hoses, loose manifold or plenum. Lastly have the IAC ckecked.

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I had the same exact problem on my RLX a year or so ago. I narrowed it down to the IAC (idle air control) or TPS (throttle position sensor). Pete from Smooth Water Sports was nice enough to stop by on his way to pick up some boats and hook his laptop up to my boat's computer (I'm still in debt to Pete forever, as he saved me nearly a month of having my boat wait in line at my local dealer for diagnosis and repair). After a quick trip up and down the river, it was determined that the TPS was the culprit. A 10-minute fix with a new TPS and all was as good as new. Thumbup.gif

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I'm having a similar problem. My I idle very fast. And my perfect pass has problems stabilizing. If you have it set at 23. It'll first go up to 30, then come back down to 21, and kind of bounce up and down from 22-24 from there. Even when just going straight no smooth water.

Does anyone know if the Throttle position sensor cause both of these problems??

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I had idle rise to 1100 rpm. With ehgine running, pushed throttle plate closed at cable linkage attachment. That lowered idle. So adjusted cable a little at the throttle plate location to allow throttle plate to close entirely. That fixed it. I would try that before you jump to all the more complicated possibilities.

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I'll try this again. My idle speed is 1500-1600 rpm. Does anyone know how to bring it back doen on an EFI engine?

Thanks everyone for your input, as usual these threads are invaluable- I couldn't have done it w/o you guys! Thanks electric john. It was a vacuum leak. I did find a disconnected hose; assumed it was idle air control. After reconnecting everything was normal. On the river for a great day. As I thought, the smoke was probably the residual can of WD-40 I used during winterization.

I still want to know how to properly fog these EFIs. Where is the fogging oil inserted??????????

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I had a similar problem, especially after towing someone. The manual solution was to pull out the nuetral pin (or whatever that thing is called) and rev the engine and the idle would slow down. When I had the boat in the shop for service recently, I explained the problem I was having. They said they found the problem (I believe they said it was a faulty sensor) and replaced it under warranty. Now it runs perfect. I have a 2007 Monsoon 340 EFI.

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I still want to know how to properly fog these EFIs. Where is the fogging oil inserted??????????

Some folks remove the spark plugs, spray a small amount into each cylinder, pull the lanyard and bump the motor over.

Others don't bother. Particularly if boat is not stored in a exceedingly humid environment.

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wd40 is very ineffective at long term lubrication. its a water displacing lubricant and evapourates rather quickly so spraying it in the cylinders does basically nothing.

you need a good fogging oil so you coat the pistons, bearings and crank with oil so rust won't form.

for any layup I'd recommend fogging the motor. it takes only a few minutes and condensation can build up in any environment. 5-10 seconds in each hole with fogging oil, then bump it over a few times.

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The smoke he's talking about came from, I believe, wd-40 sprayed on the outside of the motor. I'm assuming he used fogging oil in the intake to fog it out.

Edit: And Boeshield T9 would be better for spraying the outside of the motor.

Edited by VinRLX
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wd40 is very ineffective at long term lubrication. its a water displacing lubricant and evapourates rather quickly so spraying it in the cylinders does basically nothing.

you need a good fogging oil so you coat the pistons, bearings and crank with oil so rust won't form.

for any layup I'd recommend fogging the motor. it takes only a few minutes and condensation can build up in any environment. 5-10 seconds in each hole with fogging oil, then bump it over a few times.

The sump oil does a pretty good job of coating the crank, rods and bearings, and fogging oil shouldn't get below the rings in any quantity, or you have a problem. Pistons are aluminum, which CAN'T rust. Fogging is good treatment for cast iron cylinder heads, valves, and the cylinders above the rings. I suppose the case could be made that there is some residual coating on the cylinder walls after the rings pass, but the oil ring should take care of the lower cylinders anyway.

Unless, of course, your boat is a two-stroke.

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