Is it normal to get knock retard when????

[denali804]

I have my ltft's dialed in to show me between -.76 and 0.00. I have had a full tank of 93 octane Shell gas in for about 100 miles. I'm using the 87 tune now on my 03 denali and i'm getting knock retard when at Wot. Is it strange to get knock retard of 5.xx-6.XX wot when im running 87 tune with 93 octane fuel. Just dont want to hurt the motor.

[06MonteSS]

that's gonna happen with Shell gas (crap gas).... get all that run out of there, and fill up with some good quality gas like Mobil, Exxon, Sunoco, Amoco, BP...

I used to run Shell 93 and had the same issue with my Monte when I first started logging a couple years ago... I changed to Mobil 93, and by the second full tank of Mobil 93, my KR was virtually gone...

[denali804]

wow, I thought shell was good quality stuff. Not doubting you ss but has anyone else had the same type of issues with shell? Thanks for all your help so far ss.

[06MonteSS]

not speaking for anyone else... but yes - around the forums, they have all posted the same results with Shell gas....

they guys here at diablosport will tell ya the same..

in fact, they told me that one Vette they were tuning that came in with Shell gas, they drained the tank, and filled up with Mobil 93, and then they were able to tune an additional 20hp/tq on top of what they had already done!!! all cuz of that shell gas causing KR, and robbing the car of spark advance/timing...

once that was out/gone, they were actually able to advance it a little more and get more OOOMPH! out of it... cuz no more KR from the shell sh..tuff...

[jsk06c6]

WIth ya on the different gas as well, I use only sunoco 93. If I was stuck I'd get BP(Ammoco), I've had no luck with Mobile, I think they use too much detergent, but to each their own.

[06MonteSS]

Hmmm... interesting... maybe I'll start trying some Sunoco gas and see if that improves things any more...

thanks for the tip Jon!!

[jsk06c6]

Np, I just wish they still had the 94, but they did away with it.

[06MonteSS]

yeah, same here... I used to use that all the time...

I'd run the Sunoco/CAM2 100 octane unleaded more if it was less costly but it's close to $7.90 a gallon here... so I only treat myself once in a while... but lemme tell ya, the car LOVES that stuff....