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2003 chevy trailblazer_lt_ext
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1 Posts
Discussion Starter #1
My 2003 TB all of the sudden started running bad at a stoplight. Check engine light flashed and then came on steady. Checked code when I arrived home. P0306, misfire cylinder 6. After going through the forum I decided to swap ignition coil 2 and 6 to see if the problem would move to cylinder 2. DON'T DO IT!:duh: After I swapped ignition coils the computer came back with a code p0300, generic misfire. It takes to long for the computer to figure out where the problem is. Back to the forum for more guidance. Found the perfect answer. Remove the coil connecters one at a time. If you remove the connector from a good ignition coil the engine will run even worse. If you remove the connector from a bad ignition coil there is no change in the engine performance. Once I removed the connector from the now bad position 2, there was no change in how the engine ran. Replaced the coil and now it runs grrrrrrrrrrreat!!!!!!! I love this forum!:woohoo:
 

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2003 gmc envoy_slt_xl
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9 Posts
I was about to go through that tomorrow as I am having the same issue, I am sure you just saved me lots of trouble shooting time.
Can you remove the coil wires when the vehicle is running?
Thank you
 

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2002 chevy trailblazer_ltz
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96 Posts
Bad ignition coil pack.

Truck must be fully warmed up and in closed loop operation or you will get a generic code 300. Word to the wise I have had 2 of these coil packs go bad. Carry 1 in the vehicle if you don't want to get stranded. Cheap insurance and easy to change on the road. :yes:
 

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2002 olds bravada
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17 Posts
Thank you TrailVoy.

I put in new spark plugs in preparation for a little trip tonight. My wife had been complaining about occasional rough running (the steering wheel was shaking when stopped at a traffic light). After installing new plugs I had a constant miss. No codes. Drove it around the block and eventually saw a blinking SES light. Code reader pulled a P0300.

Learned in this thread that you can disconnect the coils while running. I was worried this could damage the engine controller. Found that #2 was missing. Put in a used coil from the yard down the road and all is well again. I have a spare in the under floor compartment with enough tools to change it should another fail. This makes 3 failed coils in 160K miles. The previous two were ID'd as bad by the ODBC reader, this is the first P0300.

Thanks again.
 
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