zeeseventyone

Background:

5.3 L33 stock harness and PCM
223/227 .61x.61 111+2 Cam
243 milled .30 with .10 thinner head gasket

stock injectors stock intake stock TB. Truck ran fine before cam swap. pulled it in for cam swap, swapped cam, and heads got a base tune for startup.

open loop it's fine.

closed loop bank 2 O2 lowers (shows lean) and reads steady while Bank 2 fuel trims shoot up to 29% to add fuel. (when it doesn't need it)

running pig rich on bank 2. bank 1 is perfectly fine.

plugs 6 and 8 look wet. 2 and 4 just look carboned up from excess fuel.

tried swapping coils, tried swapping injectors, tried a new O2 sensors, tried looking for vacuum leaks, passes cylinder balance test, tried tuning MAF several times. no matter what I did, 6 & 8 look wet and bank 2 trims SHOOT up to 29%

I've tested all injector wiring with a test light for constant voltage.. tried different injectors, I'm out of ideas.

someone please chime in. this is my DD and don't have much more to do to it. I'll send anyone hpt data log via email.

RockinWs6

With 6 & 8 misfiring the 02 will go lean because there is too much o2 in the exhaust so it adds fuel. You need to find why those cylinders are not burning fuel. Do compression and leak down tests, check for spark too.