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Dan, Technician
Category: Chevy
Satisfied Customers: 24442
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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2004 Chevy Silverado 2500: Service engine light is on..coil packs

Resolved Question:

I have a 2004 Chevy Silverado 2500. Service engine light is on and the computer reads mulit-cylinder misfire. Was told possible coil packs. Should I change all eight or is there a way to tell which one is bad. Or is that the problem?
Submitted: 7 years ago.
Category: Chevy
Expert:  Dan replied 7 years ago.
What size engine? Thanks
Customer: replied 7 years ago.
Expert:  Dan replied 7 years ago.
Does it run rough? Has any work been done recently such as the crankshaft sensor being replaced or battery disconnected? Thanks
Customer: replied 7 years ago.
no runs well gas millage down a little
Expert:  Dan replied 7 years ago.
Did you have this diagnosed at a dealer or independent shop? thanks
Customer: replied 7 years ago.
independent shop
Expert:  Dan replied 7 years ago.
Ok.....well I HIGHLY doubt a coil is causing the problem because if it was you would have a problem with only one cylinder and it wouldnt run good......It is more likely you have a vacuum leak, dirty throttle body, dirty mass airflow sensor, or the vehicle might need a crankshaft position sensor relearn procedure done which has to be done by a scantool at the dealership......At this point I'd recommend cleaning the throttle body and mass airflow sensor yourself while looking for vacuum leaks and if you dont find anything bring vheicle to the dealership and recommend they do a crankshaft position relearn procedure. Let me know if you have questions, thanks.
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Customer: replied 7 years ago.
Thanks for all the information. I will try all that.