Idle Speed Control valve (ISC)

[1madbird]

Can some one tell me what exactly this vavle does. I belive mine is bad due to the fact that my sled is hard to start when it gets hot and the valve is very hot and ohms out of spec.

 

[Zakre]

This valve allows the engine to control the idle speed when the throttle is fully closed, aka when you start the sled it idles high ~2200 rpm plus to warm it up and as the sled warms the computer closes the valve a bit to slow the idle down to ~1550.

 

[1madbird]

Zakre I know it controls the idle but how? It has no control on the linkage and the only thing I can see is it controls vacum or something to each throttle valve.
The issue I think I am haveing with mine is when its cold it starts right up but when it gets hot it wont start and the manual says if the valve sticks closed it wont start. Not sure what this would have to do with it starting.

 

[yamahaboy701]

You can check if the ISC in the diagnostic mode. It is extremely easy to do and you can do it right on the trails when the sled is hot. Diagnostic mode will open and close it 5 times and you will be able to hear it each time if you don't you might have a problem. You will need a service manual for the steps to get into diagnostic mode and the code numbers.

 

[Zakre]

Zakre I know it controls the idle but how? It has no control on the linkage and the only thing I can see is it controls vacum or something to each throttle valve.
The issue I think I am haveing with mine is when its cold it starts right up but when it gets hot it wont start and the manual says if the valve sticks closed it wont start. Not sure what this would have to do with it starting.

its a smalll solenoid that opens and closes an air path for the engine while the TB's are closed. Its simailar to the IAC on a car just a small little hole that lets enough air by to idle. If the valve is stuck or not respoding I would test it first or when the sled is hot will it start if you give it a bit of the flipper, in other words let in some air so she can run?

 

[1madbird]

I messed around with it last night and figured out that it just lets a controlled amount of air past the throttle valves when they are close the more air the higher the idle. I have went through the diagnostics and it seems to work fine when it is cold but just because you can hear it move doesnt mean it is going to the correct position. I have tryed to give it some throttle when it wont start and it doesnt make any difference but with fuel injection I think when it see the throttle move it does something to the fuel. I know with cars they tell you to not give it gas when trying to start. I am borrowing a friends tonight to see what it does and will post back my results I sure hope this is the problem

 

[Beauryan Best]

I messed around with it last night and figured out that it just lets a controlled amount of air past the throttle valves when they are close the more air the higher the idle. I have went through the diagnostics and it seems to work fine when it is cold but just because you can hear it move doesnt mean it is going to the correct position. I have tryed to give it some throttle when it wont start and it doesnt make any difference but with fuel injection I think when it see the throttle move it does something to the fuel. I know with cars they tell you to not give it gas when trying to start. I am borrowing a friends tonight to see what it does and will post back my results I sure hope this is the problem

Did you figure it out?