Originally Posted by
InTruckDesign
Just recently I have been noticing some pinging/detonation in the 4,000-5,000rpm range. The ecm tune has been unchanged for several months. I've been pulling my hair out trying to figure this out and for some reason decided to look at the % of ethanol in the fuel I am purchasing...I have found that the stations around me are all selling E-15 rather than the E-10 we have had here for years. My question is, what if anything needs/should be changed in a tune when the fuel changes in ethanol content by 5%? Thanks.