Idle speed jumping

[FoolhardyIDI]

So the idle speed has been jumping around the last week. From 650 - 750 rpm, it has done it 3 times now. No running rough or anything when it happens. Just kind of strange. I don't see any leaks anywhere. Anyone have an idea?

 

[IDIoit]

check the idle screw, and make sure nothing is in the way of the cable.
may wanna disconnect the high idle solenoid and see if that cures things....
when its warmed up, there should be a space inbetween the idle solenoid and the throttle lever.

 

[FoolhardyIDI]

The three times it done it so far. I was driven it around town so the engine was nice and warm. I also checked the linkage and saw noting in the way of binding or getting in the way of the idle screw. My high idle solenoid has never worked. Always been a huge 1/2in gap from it to the IP lever.

 

[IDIoit]

i cant think of anything else besides a throttle cable going bad.....
is the spring nice and tight?

 

[madpogue]

You'd have to "catch it in the act", that is, stand in the driveway staring at the IP with it idling warmed up, and when the idle jumps, see if the cable/throttle actually move. I'd have to think it's more something IP-internal. Hmm, come to think of it, does the cold _advance_ (separate from the cold _idle_, but controlled by the same sensor/switch) still work? Is it hooked up? Maybe that temp switch is acting up and the cold advance is kicking on and off when it's warm. You could try disconnecting the switch and see what happens.

 

[FoolhardyIDI]

Next time it does it I will disconnect the cold idle advance and see if it changes anything.