tuning.. winter blend vs summer blend

[cobra916]

since the winter gas vs summer gas has a different molecular structure.. would a car tuned with one blend not run optimal with the other blend? or will our ecu catch this and adjust accordingly?

 

[JRS03]

I would like to know this as well

 

[scooby3694]

me too. my car doesn't like the gas it is sipping currently......

 

[cobra916]

anyone?

 

[sprstr1000]

Here too??????
Whats the diff??????
Running super low timing and still getting knock

 

[sprstr1000]

If the oct rating changes for winter gas then they should advertise as such

Anyone know where to send fuel to have it analyzed?

 

[Mainn]

99% certain it will adjust accordingly. As long as the octane rating is the same, it should be fine. How would stock cars work if they only ran properly in temperatures above 0 degrees C?

 

[eficalibrator]

The stoich point and octane rating should be the same between summer and winter blends of the same advertised/sold fuel. The big difference is RVP (Reid Vapor Pressure), which is an indicator of how quickly the fuel evaporates at a temperature. Winter fuel is high RVP, so it evaporates more easily in cold temperatures. Summer fuel is low RVP to avoid vapor lock at high temps.

Chances are that if you're having a cold weather issue, it's likely a symptom of something else that's amiss in the calibration. Tuning around inaccurate injector data in the summer often leads to decent warm driveability but sketchy cold performance. There's a few other things that change with temp too, so it's tough to tell more without seeing a bunch of data and digging further.

Greg Banish
Calibrated Success, Inc.