Cold Idle problem 2001 Corolla CE - Toyota Nation Forum : Toyota Car and Truck Forums

sh0wn · 09-01-2009, 12:14 PM

Twice now I noticed when I start the car in the morning the idle will be below 500 rpm for about 20 seconds. During which the engine feels and sounds rough. After that the idle goes back to the normal cold speed of about 1100 rpms.

I haven't done any recent work on it and it's due for an oil change. I have about 156,000 KM on it.

Anyone heard of this or have any ideas on what it might be?

-sh0wn

fishexpo101 · 09-01-2009, 12:30 PM

Could be a number of things causing that. From fouled or worn sparkplugs, to bad gasoline, to vacuum leaks, various sensors, electrical issues, running oil that is too viscous (some motor oils get thicker the longer they sit in the crankcase, some shear down very quickly), more etc.

For your model year, there is also a MAF and IAT sensor in the air box (air filter cover). Given 156K KM on the clock, could be a dirty throttle body and/or dirty MAF sensor that is causing this initial stumbling. Many have reported much smoother, even idle when these are cleaned. This is also assuming that there is nothing else causing this issue.

Might be a case of just need a good tune up to fix the stumbling idle at cold temps.

sh0wn · 09-01-2009, 12:50 PM

Thanks for the quick reply!

Do you know how to clean a dirty Throttle body and MAF sensor?

I have an appt booked for a service on Friday but I'd like to see if I can make any headway before then.

fishexpo101 · 09-01-2009, 02:38 PM

Lots of info online - here are some links that I had handy:

http://www.spydermagazine.com/2002/M.../maf_clean.htm
(On a MR2 - but same principle)

http://www.4x4wire.com/toyota/mainte...throttle_body/
(On a V6 engine - but same principle)

http://www.corolland.com/forums/inde...ost__p__159456
(Write up I did some time ago on my 2002 Corolla)

sh0wn · 09-01-2009, 05:11 PM

Thanks alot for all the good stuff! I'll let you know how it goes

sh0wn · 09-02-2009, 10:08 AM

The car is idling much smoother after I cleaned the Throttle body and MAF sensor. Awesome! I'll do this on my dad's corolla too!

The initial problem of rough and low idling during a cold start is still there. Any more ideas that I could try?

fishexpo101 · 09-02-2009, 10:15 AM

I'd pull the plugs and read them. Even if they still look good - double check the gap. Even off a little bit (should be 0.044" gap) - they would cause stumbling when cold.

Could be a vacuum leak, electrical noise, or possible fuel issue (bad gas, not enough initial fuel pressure, etc.) - but will take more diagnostic work before you can narrow down the field.

Also, it helps the engine computer relearn new settings if you pull the negative battery cable off for a minute or so - to clean the ECM. Since you cleaned the TB and MAF sensor, you need to "jumpstart" the ECM to notice the improvements. Note that if you have an alarm system - it might not be too happy about this. Radio presets will be wiped as well. Other option is to use a OBD-2 scanner to reset the ECM.

sh0wn · 09-02-2009, 11:57 AM

I'll check the pluggs and kill the power to reset everything. I'll post the results tomorrow.

Thanks alot for your help!

sh0wn · 09-03-2009, 05:22 PM

The car started fine this morning. I disconnected the power overnight. I'll monitor it and post the results.

sh0wn · 09-08-2009, 01:02 PM

Just got lucky the one time. The problem is back every morning now.

grayface44 · 09-08-2009, 07:58 PM

I have a similar problem. I tried everything from MAF, IAC, TB, and all the Vac lines. The problem was a leaking O-ring on the Injector. Apparently a common problem on this car, or so i was told. Mine started as an air leak, then this morning blew completely and spat GAS all over the place. I took it to a shop today and they fixed it for $50!! Easy fix for a shop.... get the Injector rings looked at... Hope this helps