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lexpert, Lexus Master tech
Category: Lexus
Satisfied Customers: 2100
Experience:  Master Certified with lexus, 8 years experience with Lexus
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Lexus ES 300: I put a new alternator in my 2003 Lexus 300.

Customer Question

I put a new alternator in my 2003 Lexus 300. Afterward, it would not maintain at idle. Kept dying.Drove it 20 miles to "reset" the computer. Still died. Battery and alternator test ok. I let it idle at 1500 rpm for 15 minutes but still would not maintain idle. Repeated. Still won't idle...just dies.
Submitted: 2 years ago.
Category: Lexus
Expert:  Victor replied 2 years ago.
Hello and welcome to JustAnswer.There's is a valve attached below the throttle body. This valve controls the idle. It gets carboned up. Remove the intake rubber bellow and spray some carb throttle cleaner into the valve. There are small ports at the bottom of the throttle bore. Spray cleaner into these ports. Button everything up and start it up and see if the car idle differently.
Customer: replied 2 years ago.
why would replacing the alternator cause problems with the valve?
Expert:  Victor replied 2 years ago.
By disconnecting and reconnecting the power source, the valve resets. If the valve has too much carbon build up, it will have a tough time moving back to its original position.
Expert:  Victor replied 2 years ago.
Hello, just following up. Did the cleaning help with the idle?