Strange Idle Problem Similar to Another Post

[Stratnick]

I recently removed the carbs on my 2000 I/S. I cleaned them, replaced slow and main jets, and replaced all orings, etc. The engine ran sooo much better and all of the stumbling, etc. stopped. After the weather warmed up, I noticed that the engine would idle really high after warm up, especially after letting it sit for a few minutes. After the engine cools back down, it idles normally again. One day, after arriving home, I let it sit and idle fast. Then the radiator fan came on, and it began to idle at normal speed. On another post, someone suggested a problem with the coolant temp. sensor. Could this really be the culprit? Thanks for any suggestions.

[Chrisj CMA]

you cant adjust the idle to 900-1000 once its warmed up with the knob?

[R J]

you cant adjust the idle to 900-1000 once its warmed up with the knob?

THEN, don't muck with it afterwards.    It is normal to run a little rough at times  on a cold start and NO choke.   That is one of the reasons you keep your fingers off the throttle when ya 1st start it and try to give it some gas, it will usually die.

[Patrick]

Like the fellas said, set the idle speed when the engine is good and warm and leave it alone.. Since you just stuck the carburetors back together, you may want to consider a sync..

[salty1]

+1 on carburetor synchronization ! 

[Stratnick]

I plan to do that as soon as I get some gauges. As I said, most of the time, even when at normal operating temp, it idles as it should, around 900 rpm. Then after sitting on a hot day for a few minutes, it will idle fine after starting, but then idle around 1500 or so randomly. Then the radiator fan straightened it out. I'm a pretty good mechanic, but this has me scratching my head. it's not an idle adjustment problem, there's something abnormal going on. I put #35 slows in and turned mixture screws out 2.25 turns.  I will sync carbs, then report what happens. Meanwhile, any other advice will be appreciated. Thanks for responses.

[Patrick]

Are you sure there isn't a throttle cable issue ?? About the carb sync, all thats needed is a plain ole vanilla style vacuum gauge and some vacuum line and maybe some forceps..

[Stratnick]

Are you sure there isn't a throttle cable issue ?? About the carb sync, all thats needed is a plain ole vanilla style vacuum gauge and some vacuum line and maybe some forceps..

I don't believe its a cable issue. I checked that and it all was working as it should...no binding, etc. What is a vanilla style vacuum gauge? Thanks.

[Patrick]

A plain vanilla style vacuum gauge means that its just a plain ole vacuum gauge [preferably with a damper].. You really don't need anything fancy to sync these carburetors..

[Stratnick]

A plain vanilla style vacuum gauge means that its just a plain ole vacuum gauge [preferably with a damper].. You really don't need anything fancy to sync these carburetors..

thanks. Where can I get one? Do auto parts stores have them?

[salty1]

Good ole Harbor Freight has them. Search here and the VOAI site for what folks have done to accomplish carburetor synchronization. Motion Pro also has the tools for the job too. Good Luck! 

[Chiefy]

Mine did something similar, but not identical to yours when I bought it used.  The dealer fixed it free.  He told me the choke apparatus on top of the carbs was the problem.  I didn't ask for more details.  Might be something to look at.  My idle would randomly be fine, then be high at different stops.  Reaching down and fiddling with the choke slides caused it to change.

Yeah-yeah I know, the stealer is crazy.