Cylinders 3 and 4 misfire?

Tiny
CLI3200
  • MEMBER
  • 2002 GMC SONOMA
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 156,000 MILES
My truck listed above runs and drives fine with the misfire codes it’s throwing, but you can tell at idle it definitely has a miss. Has new plugs, wires, injectors, rotor, and cap points cleaned, new MAF and it still has cylinders 3 and 4 misfire. There is no gas or coolant in the oil, not burning any coolant and no oil in coolant. I'm kind of at a loss and don’t know what to do next.
Monday, May 1st, 2023 AT 7:46 AM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
These engines had a problem with the spider injector inside the intake manifold. But we should do a compression test to make sure the engine is okay.

This guide can help:

https://www.2carpros.com/articles/how-to-test-engine-compression

And this guide can help as well:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Here is how to change the injectors out in case you need them in the images below. I would use an OEM unit. Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

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Monday, May 1st, 2023 AT 11:08 AM

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