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Old 07-11-2008, 10:08 PM   #1
gibbon_guy
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Default Toyota Corolla - high idle

I am having an issue with my Toyota. I have a 4A-FE in my 1990 Toyota Corolla All-Trac Wagon SR5 with a M/T.

On cold start up my idle is 2000 rpm. When warm, it's 1100 with the blower motor and head lights on. I have checked for vacuum leaks, haven't found any. I used a smoke machine; I pressurized the system;I checked the idle air valve at the bottom of the throttle body. If I place my finger over the hole, the idle drops to 900 rpms when cold. I am at a loss as to what is causing such a high idle. Another possible symptom is that when I hit the "Lock" switch for the front diff., the diff does engage but if I hit the switch, it doesn't disengage unless I turn the steering wheel.

My coworkers at our shop say intake manifold gasket and throttle body gasket. Should I do it just to be on the safe side or is there something else I can check first?
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Old 07-11-2008, 11:25 PM   #2
ImportTuner
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Default Re: Toyota Corolla - high idle

Check the TPS (throttle position sensor) at the throttle body ...
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Old 07-12-2008, 01:00 AM   #3
BooUrns!
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Default Re: Toyota Corolla - high idle

Great car, not so much on the pretty side but definately a solid car for winter. The 4wd gave it a great advantage on our roads, especially up here where we see deep snow, black ice and -25c. I grew up with one. My mother finally retired it last fall.
They are importing tonnes of right hand drive models of that Toyota to western Canada these days. It was sold in Japan as the Toyota Sprinter Carib, the bambi bars and other details on those imports really make them look interesting.
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Old 07-12-2008, 08:19 PM   #4
stuckinohio
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Default Re: Toyota Corolla - high idle

I'm pretty sure there was still an idle speed adjusting screw under a rubber plug on top of the throttle body on that year 4A-FE. If so, have you adjusted it?

The TPS could need adjusting or replaced, and also carbon build up in the throttle bore could be keeping the plate open a hair and needs to be cleaned.

Does the cable have some slack in it when the throttle is shut?

If some one else has tried to fix this, they could have messed with the throttle stop screw thinking it was for idle speed adjustment, which could keep the throttle open too far and throw off the TPS signal. There usually is some paint on the screw and locknut. If the paints been broken, someone messed with it.
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Old 07-13-2008, 04:50 AM   #5
Kevin54
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Default Re: Toyota Corolla - high idle

Although this is for a 22RE, check this read on a throttle position sensor and see if it gives you any insight. Vacuum leak would have been my first guess too. But from the Toy's that I have owned, they do idle what seems unusually high when cold. It sounds like yours is normal. You may want to adjust the idle somewhat after warm and get it down to around 800-900 http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml or this http://www.240sx.org/faq/articles/th...or_adjustm.htm You have a variety of sensors that could contribute to it . A MAF sensor, MAP sensor, etc. All sensors affect the way the ECU will operate. One goes bad, the computer will compensate for it, therefore affecting other things. But as I said, 2000 is not abnormal for an older cold engine in a Toy. 1100 seems a LITTLE high but not bad. Adjust it down and you should be fine. But adjust it after the engine has warmed up and not before.


Or check this for Toyota high idle problems http://autorepair.about.com/library/faqs/bl179i.htm

Last edited by Kevin54; 07-13-2008 at 05:02 AM.
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Old 07-13-2008, 09:00 PM   #6
Gabriel J
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Default Re: Toyota Corolla - high idle



The Idle Speed Control Valve controls idle speed by allowing additional air into the intake plenum. The ISC Valve is mounted on the front end of the intake plenum and operates as a vacuum switching valve when the ECU grounds the circuit. The ECU senses electrical loads and uses the fixed idle parameters to maintain proper idle specifications. The ISC Valve inputs the ECU through terminal V-ISC.
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Old 07-13-2008, 09:01 PM   #7
Gabriel J
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Default Re: Toyota Corolla - high idle



Check and see if the ISC valve is sticking/seized.....Best I could do for now...-Gabe
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