Regular gas spark knock

[WJCO]

More resurrection on this thread about spark knock and fuel quality!

I have a 2010 JKU. I bought the truck slightly used with 3k on it in Denver, and drove it back to Detroit.

Since then, I've had to use premium in it where I live to cease the spark knock - especially in summer months.

However, I have gone out of town a few times with the Jeep and have noticed a dramatic difference in mileage and knocking with fuel out of my immediate area in Michigan. Just over the holidays, I was on the west side of Michigan and filled up at a Meijer station with 87 octane and to my surprise, I got 20-21 mpg on the highway going back to the east side of the state! Zero spark knock also. I use Meijer also where I live, because I grocery shop there and get points/discounts that can be used at the fuel station.

I posted a question on another jeep forum, and the consistency answers I received was a different in Ethanol content.
I found a station near me that sells Recreation Fuel at 90 octane, zero Ethanol. I tried it, and sure enough, no spark knock and 20 mpg around town. But at $5/gallon, that isn't a long-term solution.

So in my case at least, Ethanol seems to be the culprit. I've not had this trouble before with other vehicles, even from my BMW motorcycle. But it seems there is a difference in fuel quality and Ethanol content at the Meijer stations around Michigan. Interesting!

Epic first post from joining 9 years ago

 

[bobfriesenhahn]

More resurrection on this thread about spark knock and fuel quality!

I have a 2010 JKU. I bought the truck slightly used with 3k on it in Denver, and drove it back to Detroit.

Since then, I've had to use premium in it where I live to cease the spark knock - especially in summer months.

However, I have gone out of town a few times with the Jeep and have noticed a dramatic difference in mileage and knocking with fuel out of my immediate area in Michigan. Just over the holidays, I was on the west side of Michigan and filled up at a Meijer station with 87 octane and to my surprise, I got 20-21 mpg on the highway going back to the east side of the state! Zero spark knock also. I use Meijer also where I live, because I grocery shop there and get points/discounts that can be used at the fuel station.

I posted a question on another jeep forum, and the consistency answers I received was a different in Ethanol content.
I found a station near me that sells Recreation Fuel at 90 octane, zero Ethanol. I tried it, and sure enough, no spark knock and 20 mpg around town. But at $5/gallon, that isn't a long-term solution.

So in my case at least, Ethanol seems to be the culprit. I've not had this trouble before with other vehicles, even from my BMW motorcycle. But it seems there is a difference in fuel quality and Ethanol content at the Meijer stations around Michigan. Interesting!

Don't know who 'Meijer' is. Some stations are ambivalent about where they get their gas. If they get their gas via a network (e.g. Chevron), then it usually says so on the pump.

 

[rich67]

I got the CEL knock sensor circuit code while traveling to Georgia from Florida the other day. Bad engine knocking even at low RPM. Apparently Ga gas is complete watered down garbage. Went from 15 mpg towing a camper down to 11 mpg. Cleared the code and gassed up in Florida and went back up to 14 mpg. Now dealing with the residual garbage and still getting the code. It will take a couple tanks to flush and get back to normal, I guess.

 

[cozdude]

I got the CEL knock sensor circuit code while traveling to Georgia from Florida the other day. Bad engine knocking even at low RPM. Apparently Ga gas is complete watered down garbage. Went from 15 mpg towing a camper down to 11 mpg. Cleared the code and gassed up in Florida and went back up to 14 mpg. Now dealing with the residual garbage and still getting the code. It will take a couple tanks to flush and get back to normal, I guess.

Run a tank of 93 in it and it will help push it thru. You can also put in a fuel stabilizer to help get the water iut