Mattey MES

Tuner has no clue saying fuel pump ? But it doesn’t make sense. stock intake haven’t investigated further. will data log this week.

Cats got clogged due to another misfire. Bad coil. Left side cat was slightly clogged and wouldn’t let enough air out at wot. truck was re tuned when cats were gutted.

Just a multiple missfire code. hard to show the problem without giving it lol you can actually see it “break” out of the mis

Just a multiple missfire code.

What exactly is closed vs open loop?

Yea scanned it multiple misfire code. Drove it with the scanner hooked up pretty well all cylinders on both banks missfire all random it bounces between cylinders. No particular cylinder misfires. Also zero misfire when warmed up.

2014 sierra 5.3 currently 430xxx km or around 265 miles misfire when cold feels like it’s running on 4 cylinders rough idle. When driving cold feels like it needs to break out of the misfire then goes full power. Will attach video. No major work done. Didn’t change coils. New plugs and wires. Compression test showed 230-240psi across all 8. Cel flashed when misfire is “over” and stabiltrak light turns on also. After the truck has its moment the misfire goes away completely while driving. truck is stock. DOD deleted since new gutted cats. They were clogged