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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1685
Experience:  GM Grand Master Technician 2007. 14 year experience.
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I just bought a 2002 envoy sle. It has 121000 miles. It had

Customer Question

I just bought a 2002 envoy sle. It has 121000 miles. It had a miss in it. So I replaced the fuel filter,rear 02 sensor,crankshaft and camshaft sensor and spark plugs. The plugs I used were ac delco. Now it has a worse miss then before. What did I do wrong
Submitted: 1 year ago.
Category: GMC
Customer: replied 1 year ago.
The service engine light is on now. I noticed that 3,4,5 coil packs were new.
Expert:  AZTechBrian replied 1 year ago.

That's a bummer. Sorry you have waited so long for a reply. Are you able to get the codes? I would bet it's just another bad ignition coil. If you can't get the code, you can do a power balance test by unplugging the fuel injectors one at a time and which ever cylinder has no drop in rpm when the injector wire is pulled is the misfiring cylinder. It would be best though to get the code. Let me know what your code reads.

Customer: replied 1 year ago.
OK thank you. I'm going to go get a scanner and get the code. I noticed that when putting the coils back on they were hard to push down b7t when I tightened the botl they pushed right that normal?
Expert:  AZTechBrian replied 1 year ago.

That sounds normal. When you get the code let me know. Thanks