the truck is a 09 silverado 2wd that came as a 5.3. The modifications are a turbo and 6.0 block bored and stroked using 50 lb injectors. spark plugs gaped at 30 when swapped just to make sure... new battery and cleaned terminals ( they did not have any build up just wanted to make a fresh surface before install. Injectors all flow tested before install. prc heads with behive springs

The truck performs great under 8 lbs of boost pressure, no knock , no errors clean profile while data logging.

Above 8 lbs of boost the drivers side o2 bank while making dyno pulls goes lean (02 sensor reads 02 in exhaust) the fuel trims attempt to correct the issue and then all of the sudden it is fine again all while raising the rpm. logging the fuel pressure it holds steady

to try to identify / simplify the diag i have done the following 1st swapped the 02 sensors (both where new for this build but i still swapped sides) with no results, next where coil packs, spark plugs, wires , and fuel injectors the problem stayed on the drivers side bank and never moved. I checked the grounds to the block 2 on the front side of the passenger side head 1 to the body on the rear of the drivers side head by the firewall, and 2 wires right above the oil pan on the drivers side of the head. Ive checked the ecm with a lab scope and logged the results, an identical anomaly showed on wires coming out of the ecm to the coil packs while boost was over 8 lbs. I then made another run testing the voltage into the ecm to ensure i wasnt loosing ground or power to it and they both stated perfect durring the run. the coil packs drivers showed as low as 3 volts coming out and 4.8 as the high but held steady at 4.8 on the other side. I took this as confirmation of a bad ecm but when replaced and new hp credits where purchased this morning .... it was not a good diagnosis. The problem continues and Im just looking for some suggestions / ideas to fix the problem.

If you can properly diagnose / identify what is causing this issue you will receive. 400.00 by check , PayPal, cashiers check , or pizza and beer delivered to your door lol. Not going to just swap parts until it is repaired. I need a way to test the reccomended repair an then if it is a legitimate fix you will be publicly praised and paid for your skills.

 

Needs to check the temp of each cylinder on that side. If a cylinder starts to miss slightly it'll show lean. All it takes is one cylinder to cause the problem. Could be a weak spring or a lifter preload issue.

 

What plugs are you running? Have you read them right after the 02 us showing lean?