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Ask Michael Moore Your Own Question
Michael Moore
Category: Chevy
Satisfied Customers: 2956
Experience:  ASE Master/GM WORLD CLASS/GM Master/GM ASEP/Dodge Gold/Mazda cert.
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2000 chevy malibu: oil change..rpms are fluctuating..clunking sound

Customer Question

2000 chevy malibu had an oil change now the rpms are fluctuating and when thrown into gear makes a clunking sound
Submitted: 8 years ago.
Category: Chevy
Expert:  Michael Moore replied 8 years ago.

Sounds like something was leaft disconnected. Did you do the oil change or another shop? If you leave the oil fill cap off/loose or the dip stick loose, this could cause a vacuum leak, this will allow air to bypass the mass air flow sensor and the computer may be trying to make up for this. also if you checked the air filter, you may have left the intake air temp unpluged (located in the air hose between the air filter and the engine throttle body). also check the mass air flow sensor (located in the same hose from the air filter to the engine). one last check, check the air hose from the air filter to the engine and make sure its tigh, may have a air leak that by-passes the mass air flow sensor(large square sensor in the air hose).


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Customer: replied 8 years ago.
Okay so that seems to take care of what could cause the rpms to fluctuate but what about the clunking transmission? This is what happened after taking the car to jiffy lube.
Expert:  Michael Moore replied 8 years ago.
If the intake air temp or mass air flow sensor was left unpluged, the engine computer will go in to a default for the transmission control and cause the trans fluid pressure to go to max pressure. this will cause a hard/harsh shift and engagment in to gear.

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