I am tuning my '98 C5. AFR heads, G5X3, LS6 intake, long tubes, 30 lbs SVO injectors. Recently hooked up LC-1 for some SD tuning.
All is going well except the wideband is reading extremely lean AFRs for the first 5 - 10 mins. after a restart. Happens when car is hot or cold. Happens with my SD tune and with my full MAF tune.
I wasn't too concerned about this - i've learned to let the AFRs stablize and richen up before beginning any serious logging. However, I start working on my idle trims. After making adjustments, the cats began glowing as the trims worked down close to 0. I have rear O2 sims so no COT richening.
I've put the idle values back to keep it artifically rich for the time being. After talking to some other folks, I am learning this 5+ mins of extremely lean AFR is not normal.
Wracking my very small brain here. Any ideas?