95GMC
07-12-2022, 02:59 PM
Back to tuning on my POS 95 Sierra after letting it sit for a while out of sheer frustration. It's a 355 running 9.5:1 compression with a stock lt4 cam. Has a factory 5.7 tbi unit bored out to 50mm and horns shaved off with new factory spec 5.7 injectors with fuel pressure bumped up to 18psi and 30 psi big block fuel pump in the tank. Edelbrock performer intake with summit vortec heads and shorty headers. I've used Trimalyzer in open loop and gotten the AFR error to less than 5%. After switching back to closed loop I immediately found the Integrator and BLM will peg rich yet the o2 is pegged lean (verified with Tunerpro data and physically tapping into the signal at the ECM) and the truck runs like crap and the wideband is pegged lean also. I've done some reading and see this may be the o2 switching points? What can I adjust to fix this? I swear if I had known this would be this much of a pain I would have just done a stock rebuild. Thanks for any help, I've been tuning this thing off and on forever and am about ready to throw in the towel.