Knock w/ Winter Blend Gas

[Sasuketr]

Is it typical to get knock on wot with winter blend gas?

Same gas station but winter blend gas 93 octane is giving me positive 3 4 degree knock above 5500 rpm. I ve been running the lund flex fuel tune and the temps are also dropped to 30 degrees here! Shall i reload the stock tune for winter? Any suggestions?

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[wildcatgoal]

All I know is my car is going through gas much faster lately... I don't know if we in GA get "winter blend" gas. I don't understand why there is such a thing in the first place. To make the cloud coming out of the exhaust in the morning after a cold start bigger? Beats me...

 

[Sasuketr]

I guess i m going to use the stock tune for winter since i can't go wot in these weather conditions anyway. We also got 6 inches of snow already and i need less power to actually keep going lol! Snow/Wet mode engaged!

 

[15GTBEN]

Is it typical to get knock on wot with winter blend gas?

Same gas station but winter blend gas 93 octane is giving me positive 3 4 degree knock above 5500 rpm. I ve been running the lund flex fuel tune and the temps are also dropped to 30 degrees here! Shall i reload the stock tune for winter? Any suggestions?

Maybe ask your tuner to send you a file with the timing dialed back a bit to compensate for the crappy gas or throw in some Torco?

This has been my main issue with tunes in general. You never know when you're going to get a crappy tank of gas...(take that with a grain of salt, I tend to be a bit on the OCD side when it comes to my cars).

More boring but I've never experienced any knock/timing pull on the stock tune.

 

[wildcatgoal]

Well that's because the stock tune is conservative enough to work on 87 octane gas... haha.

 

[BmacIL]

All I know is my car is going through gas much faster lately... I don't know if we in GA get "winter blend" gas. I don't understand why there is such a thing in the first place. To make the cloud coming out of the exhaust in the morning after a cold start bigger? Beats me...

http://www.atlasoil.com/Blog/Whats-the-Difference-Between-Winter-Blend-and-Summer-Blend-Gasoline

Winter blend has higher vapor pressure (because with lower ambient temps, you don't need to worry about evaporation as much) and higher volatility. The higher volatility is what's causing the increased propensity to knock.

 

[Sasuketr]

Yeah i ll stick with the conservative stock tune till April i guess!

 

[Sasuketr]

Well that's because the stock tune is conservative enough to work on 87 octane gas... haha.

I thought the flex fuel tune does the same as well but apparently the spark timing table is set and still trying to give more timing but then the pcm is pulling timing due to shitty gas. I am glad the knock snensors are active and able to pull timing otherwise Kabooooom!

 

[jasonstang]

Winter blend contains butane which has pretty low octane rating.

 

[whatsup62]

Yep..Winter blend is shit. Just arrived in Iowa.

 

[Terminator2]

All I know is my car is going through gas much faster lately... I don't know if we in GA get "winter blend" gas. I don't understand why there is such a thing in the first place. To make the cloud coming out of the exhaust in the morning after a cold start bigger? Beats me...

Cooler denser air means more fuel mass needed which lowers fuel economy in and of itself. Add in that they often use a different additive package which could decrease fuel economy or different mixture of gas and ethanol in winter (usually less ethanol which should increase fuel mileage slightly).

 

[Mustang_Lou]

Here in Canada the pumps are calibrated to 15 Celsius (59 F) and because gas will expand and contract based on temperature you get screwed that way as well ... another trick in the oil co's bag.

 

[Dr. Norts]

All I know is my car is going through gas much faster lately... I don't know if we in GA get "winter blend" gas. I don't understand why there is such a thing in the first place. To make the cloud coming out of the exhaust in the morning after a cold start bigger? Beats me...

Gasoline is made up of many different chemicals, or components, not just one uniform molecule. Smaller, lighter components have a high volatility (they evaporate easily) and boil at a lower temperature, whereas heavier, more complex components don't evaporate as easily and boil at a higher temperature.

Each fuel has its own unique signature, called a distillation curve; think of it as a recipe. The distillation curve tells the chemist which components are in the fuel and what their weights (e.g., their boiling points) and quantities are in relation to each other. A simplistic way of looking at the distillation curve would be to list all the fuel's components on a sheet of paper with the heaviest ones at the bottom and the lightest ones on the top.

The trick is to have the right fuel for the right time of year. In the summer, when the temperature is high, the presence of too many light components will cause the fuel to evaporate too readily. This can result in vapour lock, an over-rich mixture and excessive evaporative emissions. In the winter, too many heavy components keep the fuel from evaporating, causing hard starting, a lean mixture, heavy hydrocarbon emissions and poor converter light-off.

Obviously, since we can't change the weather, we have to use a fuel that will optimize performance and emissions for a particular climate. To do this, fuel manufacturers use heavier components in the summer and lighter components in the winter. This is a simplification of things, but it's close enough for government work.

For reformulated winter gas, lighter, low-boiling-point components are added to the gasoline to increase volatility. This makes your car easier to start and accelerates converter light-off, thus lowering emissions. That's the official line on reformulated gas.

 

[PatrickGT]

http://newsroom.aaa.com/2013/06/what-is-the-difference-between-summer-and-winter-blend-gasoline/

Also probably wouldn't run the flex fuel tune while using regular gasoline, seems kinda obvious since it's in the name and all...

 

[Sasuketr]

http://newsroom.aaa.com/2013/06/what-is-the-difference-between-summer-and-winter-blend-gasoline/

Also probably wouldn't run the flex fuel tune while using regular gasoline, seems kinda obvious since it's in the name and all...

Can you clarify why wouldn't run the flex fuel since its in the name? Doesn't flex fuel adjust to the alcohol level and octane rating of the fuel?

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