Maik04

LOL we dooo. I hope you find a cure man :l
What im going to try doing is messing around with the iacv, the tps, and.cleaning the throttlebody. Ill be adjusting the tps and iacv and hope i find the sweet spot. Going to try to find a mulitmeter to check the resistance on them too.

ScDre

Hey, sorry for late reply. Now i am learning more about this car as i tweek with it through help of these wonderful forums, and people. I found culprit of high idle, and hopefully it will fix yours and others. The simple thing is the "throttle stop screw". Its little screw with a 8-9mm nut on it, and what was wrong with mine was that the little nut got stuck on the screw, and the throttle lever was way down, which caused high idle. Just a simple 5min adjustment,maybe 2 minutes, but if you adjusted the tps, and thought it was the tps prior of doing what i did, you may have to set tps back to way it was, or when you drive the car, and try to give it full throttle, it will pull slow like mine. So im go ahead tomorrow and adjust tps the way it was since the throttle stop screw was the culprit. Hope yours is the same problem too

Maik04

Awesomeee, where is the screw located?
Yeah i do not remember where the tps was at so i guess ill have to adjust it bit by bit.
I will report back with how it went, thanks!

Maik04

Found it! Quick question though, you adjusted the screw when the high idling was happening, or did you just adjust it and tested it out? Also, you loosened it correct?

ScDre

I adjusted it and then tested it out,but you can do it while running,doesn't mess nothing up. it fix high idle,but remember I adjusted my rod prior to finding this out,and its strange the car idles good with the tps turned all the way counter clockwise, which in turn effects the speeds above 40 mph when I tested it yesterday,so it seems I also.have bad tps,but I have spare tps and will test today, also its like cars hesitates at high speed a, but im glad I fix high idle. Hopefully yours was case also

phillup23

Did anyone ever fix this problem?

marhain

That screw you guys are touching is locked down for a reason. It sets the flow rate through the butterfly when closed and can only be adjusted with a flow bench. You idle air valves are stuck open when your cars have high idle. When they are acting up, pinch the big hose going from the black intake tube to the idle valve. Your idle should come down substantially and stop whistling as well.

bigwhite

Was going to start a new thread but this one deals with the same issues. Started out I had a low idle when the car was warm, 400rpm, the alt. would stop charging and the radio would die out. So I made the mistake of lscrewing down the idle set screw to raise the rpm. It worked but then I was still having the issue with the auto. trans. shifting very hard into drive, even at 800 rpm. So i was hoping a new tps might solve my hard shift prob. and it was orig. with 160,000 miles. So I bought an o.e. o tps and installed it and set the adjustment. Now the car wants to idle at 1100 rpm. I backed off the idle set screw and made sure there was slack in my throttle cable, still high idle. Noticed if you turn the new tps all the way ccw it will drop the idle but that is way out of spec. Am going to try pinching the small black tube as recommended by prev. poster to see if its related to the iac . Then will need to clean the throttle body , im sure its being held open by some gunk. If anyone can tell me what to do with the idle set screw would be nice.

bigwhite

So I pinched the black hose and the idle came down to 100. Im thinking I should remove iac and clean it. Will go by instructions in the sc400 hesitation guide. Marhain, yes the throttle stop screw was locked with yellow paint, but im wandering if you might be referring to the 2 other screws with yellow paint, that are beside them as far as throttlebody flow?

bigwhite

So just when I think Im going to have to pull the IAC motor and the throttle body and do cleaning and testing, I take one last look at my idle stop screw and see that it could be backed off a little. I feel this is only necessary because i first adj. it to raise idle sometime ago. Also I discovered that my throttle body throttle return spring is fallen off and laying in the intake manifold area. Prob. from when I had the engine pulled and new gaskets. So I back the screw off a couple turns and connect the spring and the idle is down to 600. Readjust the TPS and all is good.