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Dan, Technician
Category: Chevy
Satisfied Customers: 24464
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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Chevy tahoe: egr valve..misfire at low..throttle..check engine light

Resolved Question:

how to tell if egr valve is bad on 5.7 vortec chevy tahoe? misfire at low to medium throttle, idles fine. misfires at higway speed, check engine light flashing.
Submitted: 6 years ago.
Category: Chevy
Expert:  Dan replied 6 years ago.

Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Ask follow up questions, thanks.


Did you replace spark plug wires?

Customer: replied 6 years ago.
not yet, but sprayed them lightly while it was dark out, see no arcing. also found map sensor unplugged but was packed full of carbon, which i replaced.
Expert:  Dan replied 6 years ago.
I would replace the spark plug wires but you could put a plate under egr valve so it cant allow any exhaust gas to pass to see if thats the problem but I think its more likely wires.
Dan and other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
also sometimes check engine light comes on and sometimes nothing at all, also runs great early mornings when its cold out.
Expert:  Dan replied 6 years ago.
Next time check engine light comes on drive right to parts store and they can check diagnostic codes for free and that may help. Let me know if you run into questions, thanks.
Customer: replied 6 years ago.

been there done that guess im at the wrong place at the wrong time, when im usually around the code reader the check engine light is not on, but shows no store odbII stored codes either... weird.

Expert:  Dan replied 6 years ago.
You will need to drive right to the store with light on, dont even shut off vehicle....Check codes with it running so they arent erased.
Customer: replied 6 years ago.

well, would egr valve cause the check engine light to flash at highway speeds, local mechanic said check engine light flashing is bad

Customer: replied 6 years ago.
Relist: Other.
new to site hit wrong button
Expert:  Dan replied 6 years ago.
The check engine light flashing means there is a multiple cylinder misfire which could be caused by the egr valve...If it always runs good at idle you can just unplug the egr valve and see if problem stops at highway speeds if not the egr is not the problem.
Customer: replied 6 years ago.
Relist: Answer quality.
completely unspecific, please refund 14 dollars
Expert:  Dan replied 6 years ago.
You asked if egr could cause engine light flashing, YES it could......and yes its bad thing for it to flash.
Customer: replied 6 years ago.
f**k you dan I want my money back!