Has anyone seen a factory virtual flex fuel setup go awry before?
I had a customer bring back a 6.0 GMC Sierra today that was tuned last year.
The engine was pinging, mostly under medium load, low rpm. After scanning it, we found the fuel trims way out (~-13%) and the ethanol percentage at 70%, so the truck was trying to run WAY more spark than factory when the customer had 87 octane fuel in it. Everything on the truck was stock otherwise and the only changes to the engine tune was more aggressive PE mode. Has anyone else had something similar happen? Could the MAF have caused this?