2003 Toyota Tacoma Engine stalling at idle, hot or cold.

ROVEROFFROADER

MEMBER
2003 TOYOTA TACOMA
4 CYL
2WD
AUTOMATIC
69,500 MILES

About six months ago, after a brief stop at a store, the truck would occasionally refuse to start unless the accelerator were depressed, and then it would run fine. Gradually, this problem became worse and more prevalent. Now, the truck refuses to idle most of the time, and is now very difficult to start even when cold.

All vacuum-hoses appear to be in good condition and the fuel filter is new. I listened to the idle-air control valve with a stethoscope while the ignition was being turned on, and heard only a buzzing, not the click of a moving part. I do not know what to expect to hear. The fuel-pressure-regulator is one of my suspicions, but I am not sure. I do not know what to try next. What are your thoughts?

Thank you for your time,

Chris

3 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi Chris,

Thank you for the donation.

The IAC would only move with a buzz and descriptions indicates it is working. However if engine does not idle, then the IAC could be dirtuy and partially clogged. That would restrict air flow resulting in it not working efficiently.

You would need to test the fuel pressure to eliminate that as a cause. Try turning the ignition on for 2 seconds. Turn off and on again. Repeat for 3 or 4 times and try starting. If it is easier to start, the fuel pressure is suspect.

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Sunday, July 4th, 2010 AT 2:38 AM

ROVEROFFROADER

MEMBER
2 POSTS

The problem turned out to be the idle air control valve. I took it apart and found that it was fouled with carbon. After scraping off the carbon, the control valve was then able to move freely. After re-installation, the truck started up first try!

Thanks for your help!

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Wednesday, July 7th, 2010 AT 10:38 PM

KHLOW2008

MECHANIC
41,815 POSTS

You're welcome and thank you for the feedback.

Glad to know you have fixed the problem. Carb cleaner is a good cleaning agent fot the IAC and you can try spraying some into the IAC air ports to lear up the passages. Note that you might have difficulty starting for the first time after carb cleaner is used.

Have a nicve day.

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Thursday, July 8th, 2010 AT 8:56 AM