1k to 2k idle climb when stopping

[Kaleid]

I've read about high idle issues on the site but wanted to mention my issue and get some additional feedback. Car starts normally- idles at 1k- after driving for a bit and coming to a stop the idle goes back to 1k (as it should) and then slowly climbs to 2k and stays there while still stopped. When putting the car in gear from a stop it drops the idle back down but the issue begins all over when stopping again. Linkages look good, pump rebuilt, throttle bodies rebuilt- all new parts- car was just recently restored- any thoughts? The person I would normally bring the car to is 1.5 hours away so to the extent I can diagnose/correct myself, I'd rather give it a whirl.

[NorthernThrux]

Checked the hand throttle ? Is it tensioning as it warms up ?

Ravi

[Kaleid]

Hey Ravi, yep, handle throttle is fine and responds when pulled…upon driving some more I did notice that it will be fine for a bit but after 10 minutes of driving and coming to a stop it will climb up to 2k and stay pegged there while idling.

[NorthernThrux]

Sounds like you are running a bit rich once things warm up. If you are somewhat rich then it will bog when you lift off the throttle and then return to idle.

So you might be on this edge. You stop and the idle drops to 1k and then starts to rise again. The MFI warmup thermostat could be clogged up with dried grease from the heaterbox heater line and sticking. Or much more unlikely, the thermo-time switch (actually the aux. starter relay) is stuck and you are injecting a lot more fuel. Not likely as this would be in the really rich category.

Also, I'd still double check the tension on the hand throttle cable just to be sure. Should have a bit of slack when fully down.

Ravi

[HughH]

my car did something similar a few years ago and from memory it was related to a sticky advance in the distributor. I had it completely rebuilt (and converted to point less) and no other material thing done to the car and it solved it

[boxster03]

I would guess throttle bodies worn on MFI - but u said they were rebuilt - so an expert like Ed Mayo etc will need 2 chime in

[edmayo]

When the high idle occurs disconnect the link rod that connects the cross bar to the throttle body, see if that changes the idle speed. Check the timing at 1,000 RPM, rev engine and then see if timing comes back to idle spec. Since you say car was recently restored I suspect mis-adjusted linkage somewhere.

[NorthernThrux]

Ed,

Always like these learning opportunities. Why would the linkage only act up when it is warm ?

Ravi

[beh911]

Heat expansion

[NorthernThrux]

Heat expansion

Thanks. Always nice to know what to look for. Hopefully I'm good for a few years before I have to chase down problems like that.