I'm not sure if this has been covered, but I'd like to start a thread about pump gas quality from different stations. It is know that some parts of the world and even neighboring states only sell 91 octane. This may apply to the 91 octane crowd just the same from station to station.
As a tuner, there has always been an issue with knock in the 2.2 Daytona even with small amounts of boost or part throttle and low timing which may be from compression ratio or an oil intrusion problem in the cylinders, especially in very hot Texas weather. I live in Dallas area and it drives me crazy when the only place I can find 93 octane which makes all the knock go away is at a small 7 Eleven down the highway (which also gives me the worse gas mileage and best performance). I believe this is Citgo fuel, but not all 7 Eleven fuel in other places treat the Daytona with the same respect if it is tuned for the Citgo fuel.
If I have to fill up at the Texaco down the road, the car immediately starts retarding cylinders at part throttle which is uncontrollable until I start removing ignition timing. I've had the same experience with Cheveron and Shell fuels.
Does anyone else have this experience?
Is it possible these places are selling us 87 octane from the 93 octane pumps?
Is it just possible this Citgo fuel is designed to produce less gas mileage for more consumption?
What are your thoughts?