corolla high idle - Toyota Nation Forum : Toyota Car and Truck Forums

eishiba · 01-04-2012, 10:09 PM

My 91 is idling almost an entire thousand higher than normal while in neutral. Its a 5 speed if that matters. Usually when you start it, it would go up to about 12 or 13 (thousand)rpm. Then it would slowly go down to about 800 while just idling. Now it will shoot up to 22 and then idle down to about 15. Do I have a sensor going bad? It runs fine while in gear and driving, but when you take it out of gear or push in the clutch, the rpms goes back up. I was starting to think maybe I need to re adjust the throttle. TPS sensor maybe? What would a bad TPS sensor do if it failed?

eberbs1 · 01-05-2012, 01:21 AM

I assume it being a 91 its EFI?
Have you checked all your vacuum hoses for leaks?

eishiba · 01-05-2012, 05:16 AM

I know they are all connected. I haven't checked for leaks though. I will try that and get back here.

90 GP · 01-05-2012, 05:41 AM

Bad thermostat . Gummed up IAC valve sticking and keeping idle high. Remove air intake and look for large ports in throttle body just ahead of throttle plate. Should feel vac when put finger over port when engine is cold. When warmed up should not feel any vac. Spray ports with throttle body cleaner to free it up.

eishiba · 01-05-2012, 06:50 AM

If it was a bad thermostat wouldn't it over heat? I'm not having that issue.

codeNO · 01-05-2012, 09:20 AM

First of all...what engine is it?? Anyway, all engines have screw to correct neutral idle.. That is 90% of your problem. Second...when it is neutral and having 1200rpm and you touch a little gas pedal..does it idle returns to normal of 850rmp??. If it does, your throttle is jammed...arround batterfly is greasily. Put out air flow plastic and clean it with wd40!! easy

eishiba · 01-05-2012, 04:46 PM

its the 1.6 4afe. with it in neutral it never goes down to 1200 anymore. It will idle at 1500 at the same time it would always idle at 850. If you tap the gas pedal while in neutral it doesn't go back down to 850. It just stays at the 1500 or 2200 if it just started.

codeNO · 01-05-2012, 05:27 PM

Ok, fixing idle can be done only when engine is hot (working temperature) This is engine of 1.3 but it is same procedure. http://imgur.com/pt6df red curcle is where need to fix with screwdrive this idle, left is for less rpm, I hope you have taco

If that doesnt help, probably idle gone out...it could be electronic inside, vacuum regulator, or sensor of water temperature, but dont think so, because you didnt mention that engine work incorrectly

90 GP · 01-05-2012, 05:51 PM

Quote:

Originally Posted by eishiba

If it was a bad thermostat wouldn't it over heat? I'm not having that issue.

Not if thermostat was stuck in open position. Could also have air trapped in cooling system. Park on incline, remove rad cap, start engine , turn heater on high and run till engine is warmed up to burp off an air and top off with more antifreeze and replace cap. Either the stat isn't letting engine get to full operating temp or the IAC is gummed up either causing your idle issue. If you haven't already checked make sure throttle is closing fully(gummed up throttle plate) or binding/hanging up cable or weak return spring.

blb · 01-05-2012, 06:39 PM

Quote:

Originally Posted by eishiba

. Usually when you start it, it would go up to about 12 or 13 (thousand)rpm.

I hpoe you mean 12 to 13 hundred RPM.

Anyway, I agree with the other thoughts above. Check for vacuum leaks, need a good operational thermostat preferabally OEM Toyota, and IAC needs to be working properly.