I got the Overkill tunes for my 2013 Impala a few years ago, ran well on the 91 tune. After switching to the 87 tune I can hear it pre-igniting (or pinking as I call it) under power / uphill.
I emailed Will a few weeks ago asking for help in solving this problem, have not got a reply.
The question is, how do I solve this problem?
I have the HP Tuners tool, I'm maybe hoping someone can help walk me through what data I need to collect, how to analyze it or what to look for, and what changes need to be made.
The other alternatives I have are to put the factory tune back for 87, or take the car to someone with a dyno and spend some money on getting it dialed in.
Appreciate anyone who might be-able to help me out.