I am tuning ZL1 stroker engine as the owner said (the owner don't know the spec of his engine) CAI- headers- pulley and camshaft stage 2.5- ID1050x injectors. I am using Daytona Wego 4 for the wideband. I am facing a problem where the timing is removed around 7deg just before 6000rpm no matter what I change in the tune. I cannot find what is removing the timing. The car was previously tuned with another tuner and the AFR was way off. Does anyone have any idea what is the problem? I spent 4 hours on the dyno with 7 pulls trying to figure it out and still same problem. I do not feel comfortable for more useless pulls with heavily modified engine so. I am suspecting a tire slip on the dyno, can the slip cause this problem. He has old M/T ET street tires.
Thanks