Hi guys, I'm working on an LQ4 that I swapped into a friend's 87 K10 with a TH400. The engine has stock 30lb 8.1 injectors, a BTR Stage 2 V2 truck cam and their LS6 springs. I've had an bunch of issues with the truck, but slowly getting them sorted out. Currently our issue is that it pretty consistently is breaking up and cutting out right at 4,000 rpm +-100. The truck is running great right now at part throttle, idle and cruise, and even first gear seem to rev up fine but once it hits second gear and the engine is under more load, it breaks up.
The engine is an 05 LQ4 but the pcm was gone from the pick n pull so we snagged one from a 2005 LM7 Suburban. I've compared the tube to numerous others that i've got saved from tuning other vehicles and can't seem to find the issue. The issue is noticeable at 15:58 in the log. It runs through first gear fine then when second hits, at 3970ish rpm the injector duty cycle shoots up, delivered engine torque dips, injector PW jumps 3 ms and the commanded AFR goes from 12.45 and then begins dropping to 11.31. I've even tried disabling power enrichment to eliminate a variable yet the problem still persists and the AFR drops the same. Any help would be appreciated guys! Thanks!