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FixItMan, Master Technician
Category: Car
Satisfied Customers: 17424
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2000 lesabre: 000 miles..normal operating temp..stumble..30 seconds

Customer Question

i have a 2000 lesabra 3.8 w/151,000 miles. when the car warms up to normal operating temp it will stumble during idle, not often. it could be every 30 seconds or it could take a minute or two. when it does sometimes it will cut all the way off but most times it doesn't. there is a knock nose when it does it and sounds kinda like a spark knock. any ideas?
Submitted: 8 years ago.
Category: Car
Expert:  FixItMan replied 8 years ago.
HelloCustomer is this a super charged engine? Is the check engine light on?
Customer: replied 8 years ago.
no it is not supercharged and no check engine or MIL.
Expert:  FixItMan replied 8 years ago.
Will the vehicle always start right back up?
Customer: replied 8 years ago.
Expert:  FixItMan replied 8 years ago.
I do not think it is a spark knock, but the vehicle trying to stay running. I would start by cleaning out the throttle body. These commonly get dirty and can choke the engine at idle. It is located where the intake tube meets the engine. It can also be a clogged ful filter causing this. Is this something you plan on fixing yourself?
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Customer: replied 8 years ago.
Bobby, i tried your suggestions and i also installed a TPS and they did not work. when the engine gets, to normal temp and you drive it, it stumbles some especially under load. if you floor it, it will not always kick into passing gear but stumble worse. when you accel to speed and let off the gas, it doesn't want to slow in speed as fast as it should.
Expert:  FixItMan replied 8 years ago.
Okay. When was the vehicle last tuned up?
Customer: replied 8 years ago.
I am not really sure. my scanner read no misfires on any cylinders but i have not pulled the plugs to check them. when it stumbles during idle the clunking sound comes from the right side of the engine.
Expert:  FixItMan replied 8 years ago.
If the fuel filter has not been changed recently then start with that. Otherwise I would check the plugs and also check the plug wire connections for corrosion.
Customer: replied 8 years ago.
i have unplugged all the sensors one at the time, the only one that effects it is the mass air flow.the car runs great with it unplugged when i drive it.
Expert:  FixItMan replied 8 years ago.
That does not necessarily mean it is bad. You can remove it from the throttle body and make sure it is clean. Be sure that is does not look damaged in any way. When was the fuel filter last changed?
Customer: replied 8 years ago.
Expert:  FixItMan replied 8 years ago.
Pull the hose off of your fuel pressure regulator and see if there is any fuel in it. You should also check the fuel pressure to see if it is at spec.