Engine idles too high sometimes 04 SSV

[msutoad]

I have an 04 Launch SSV with the Assult Indmar engine. Sometimes the motor seems to idle high like at 1500 RPM, which is about 900 RPM too much. If I disengage the prop and rev the engine, it will drop down to normal, or if I turn the motor off and back on it will be normal. It does not do it all the time, and it is not just when the motor is cold or hot. The timing varies. Any idea what the cause of this might be? I know the motor is computer controlled, so I am a bit unsure.

Many thanks

[DKJBama92Mariah]

Im thinking a sticking idle air control valve.

Does anyone else have an idea? anyone...... Bueller...... Bueller. :-)


DKJ

[msutoad]

What is that, and where is it? Is it a dealer only fix, or can it be done be me at home? My boat is still under warranty, but the dealer is 162 miles from home :(.

Thanks alot.

[DKJBama92Mariah]

Sorry, its taken so long to reply. I went to the beach for the weekend and ended up sitting on my butt waiting out tropical storm arlene.

I hate to say it, but i see a long tow in your future. Since your boat is still under warranty, I couldnt with a clear conscious advise your to just start throwing parts at the boat based one my speculation.

I'm not sure exactly the layout of your motor since mine is a good old fashioned carb motor, but i'll give it a shot at describing it.

The idle air control valve (also known as a stepper motor in some applications, mostly british) regulates the amount of air entering the intake manfold when the engine is at idle and the throttle butterfly in the throttle body is completely closed. On a carb, this was accomplished by the idle stop screw which holds the primary butterflies open a little but. In an EFI motor, the idle air control valve (IAC valve) provides a bypass around the throttle butterfly for air to flow when the engine is at idle. The engine computer (ECM) uses the IAC valve and its control of the injectors to maintain idle speed. If this valve sticks, it will allow too much air into the motor, and hence, a abnormally high idle speed.

As far as where to find it, here goes. The IAC should be a device screwed into the intake plenum close to the throttle body. It will have probably 2 or 3 wires attached to it. The part screwed into the plenum will probably be about 3/4" to 1" in diameter.

Thats about all i can tell you. The only experience i've had with these was on my land rover defender. The IAC's (british term stepper motor) are notorious on these motors for getting gummed up, and sticking, causing the same symptoms you describe. I've found on my rover, that simpy pulling the valve and giving it a good cleaning with carb cleaner usually solves the problem.

Nonetheless, i would still advise just taking it to the dealer and letting them fool with it. I'm not sure how warranty work is handled, but you may not have to take it to a Supra dealer for the motor work. If i understand correctly, the engine is warranted through Indmar, not Supra, so an Indmar dealer should be able to process the warranty claim for you. This might help if there is an indmar dealer closer to you than your Supra dealer. You can search for Indmar dealers on their website www.indmar.com

Hope this helps.

Cheers,
DKJ

[KenG]

Msutoad,

I know a little about GM MEFI (version 3, which is probably older than what you have but the basics are the same). There are a few easy checks you can do yourself.

1) Make sure your throttle valve is returning fully to the stop when you return your throttle lever back to the neutral/idle position. The throttle valve stop should be fully against the stop on the throttle body at idle. If not, you could have a weak spring on the throttle valve, a binding throttle cable, etc.

2) The ECM actually uses both the IAC valve and the ignition timing to control the idle speed. If you have the jumpers to put the ECM in service-mode and an inductive timing light, check the base timing. I think 10° BTDC is normal for the GM 350 with EFI.

3) To test the IAC valve:
a) With the engine at normal operating temperature, note the engine RPM at idle.

b) Stop the engine and disconnect the IAC wiring connector at the IAC valve.

c) Restart your engine and note the engine RPM. The engine speed should be a couple hundred RPM higher with the IAC valve wiring disconnected.

d) With the engine still idling, re-attach the wiring connector to the IAC valve. The engine speed should decrease close to the original RPM noted in step a.

e) If the engine speed varied as described in steps c & d, the IAC valve is probably OK.

f) If the engine speed did not vary, then, using a 12-volt test light, with the engine running and the wiring harness disconnected from the IAC valve, test each of the four terminals in the IAC valve wiring harness. The test light should blink when connected to each one. If so, the IAC valve is probably defective. If one or more terminals do not cause the test light to blink, there may a damaged wire in the wiring harness, a poor connection at the ECM or a faulty ECM.

4) Inspect the distributor cap and rotor. The aluminum contacts inside the cap can get very corroded.

Good Luck.

--KG--

[Brian Raymond]

Do you have a Digital Pro or Wakeboard Pro installed on your boat? Brian Raymond

[msutoad]

I have Wakeboard Pro Brian. Does that matter?

Thanks to all that have replied!

Jason

[msutoad]

Brian-

Does the model of Perfect Pass matter for the idle irregularity I am referring too?

Thanks for your help.

Jason

[DKJBama92Mariah]

Toad,

To check and see if your PP is causing the problem, just unhook the PP servo cable from your throttle arm and spend a day at the lake riding the old fashioned way. If possible, i would disconnect the power to the PP when doing this so the electronics don't freak out on you.

Cheers,
DKJ

[msutoad]

Thanks for the info. I have spoken to Indmar, and they think it is the IAC valve as others have mentioned. I have it going to someone Monday to get looked at under warranty :). I will post the findings here when they are done with it.

Thanks

Jason

[jflock2]

Jason, I think I have the same problem on my SSV. What was the verdict?

[msutoad]

It was a TPS ( Throttle Position Sensor ) on the motor. It was this little plastic piece that tells the computer where the throttle position is located. Part was 100.00 or there abouts with an hour of labor. A good Indmar mechanic can properly diagnose it if they have the computer module. My guy did it first try and the part was warratied by Indmar. It is working perfectly now.

Let me know what you find yours to be.

Jason

[jflock2]

Jason, what were the results? I now have the same problem on my '02 SSV.

[msutoad]

Jflock-

The results are above in the thread before you posted. The TPS (Throttle position sensor ) was bad on my engine. 100.00 part, and 1 hour of labor solved the problem.

Hope this helps. Any Indmar service location can tell you definitively if yours is the TPS, when they hook the computer up to your motor.

Let me know what you find.

Jason

[jflock2]

msutoad, thanks! Hey, if I e-mailed you a pic of my engine, could you point out the TPS to me?

[1988comp]

you can set the choke in a hurry, just check with a manual, and make sure you do it with a dead-cold engine.

[jflock2]

Thanks for your help Jason. I'm going to purchase a new TPS and install it next week. I'll let everyone know how it turns out.

- Jim

[msutoad]

GOOD LUCK!

[jflock2]

Well, as it turns out I did not need a new TPS. The guy that sold it to me told me to check 3 or 4 other things first as he has never heard of a TPS going bad...here's what I did:

1. Make sure all hoses leading into the throttle body are air tight. There are 3 of them.
2. Check the linkage on the throttle cable/perfect pass (in idle, it should be pressed fully towards the back of the boat)
3. Use carb cleaner on the air intake valves as they may become gummed up over time.

I did all of the above and she ran fine. So I guess I'll return the TPS next week...thanks for everyone's help.

[msutoad]

Glad you got it fixed. It was a much cheaper fix than the TPS also!!!

The mechanic that installed my TPS did all of what you said, and my guy even cleaned and lubricated the IAC ( Idle Air Control) valve. None of that stuff worked on my boat. That is when he hooked the computer to the motor and the code that was being thrown pointed to the TPS.

Glad it all worked out.

Jason

Damn it man, the high idle problem is back. Same as described in the original post...I guess a trip to the dealer is in my future....Arrrggggg!

Any other suggestions before I take her in?

[tallnskinny]

My '01 22 SSV Launch is now doing the high idle thing too. I installed the RideSteady and it ran with no issues for months. 2 boat trips ago it decided 1500rpm was a good idle speed. The problem is intermittent for the first hour or so then it's constant. It will fire up and sometimes go straight to the high idle and other times it will go to 800, then 1000 then 1500 within seconds.

I felt no air leaks, see tons of fuel being sprayed onto the closed butterfly valves when the air filter is off.

TPS replace?
IAC cleaning?
Carb cleaner?
Fuel filter replacement (Anyone know which one it is? I want to do this regardless)

Thanks in advance for any suggestions or help!

-KS:confused:

[morpheusmac]

14 year old post...Start a new one...