91 octane and knocking?
Thread Starter
Instructor
Joined: Oct 2013
Posts: 194
Likes: 7
91 octane and knocking?
Since new I've always filled with 94 octane. Took a road trip in the mountains and had to fill with 91 octane. Noticed considerable knocking under load. Has anyone else experinced this? Wondering if I just got a bad tank of fuel? Since owners manual recommends 91.
Race Director
Joined: Jul 2007
Posts: 10,959
Likes: 2,641
From: Texas Hill Country
it will knock a little bit until the spark timing learns down (retards). normal when you put in a tank lower than you usually do.
the stock high octane table will ping on 93 octane as well and needs to learn towards the low octane table even when bone stock right from the factory.
GM does not use pump gas to calibrate their tunes, they use a control fuel and leave a wide margin for error for different fuels, weather, and geographic locations.
the stock high octane table will ping on 93 octane as well and needs to learn towards the low octane table even when bone stock right from the factory.
GM does not use pump gas to calibrate their tunes, they use a control fuel and leave a wide margin for error for different fuels, weather, and geographic locations.
