Cylinders 3 and 4 misfire?

2002 GMC SONOMA

156,000 MILES • 4.3L • V6 • 4WD • AUTOMATIC

CLI3200

MEMBER
2 POSTS
FOLLOW

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.

May 1, 2023 at 7:46 AM

Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.

STRAILER

AUTOMOTIVE REPAIR CONTRIBUTOR
54,189 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.

Images (Click to enlarge)

May 1, 2023 at 11:08 AM