check engine light due to 85 octane?

[wllbllck]

hey guys,

Im new to the forum and i have a 99 limited 4runner with the locking diff. I love the truck and living in CO it serves me well. My check engine light came on yesterday on the trip back from Canyonlands Nati Park. I got it checked today on a diagnostic tool and the code that came up said i was using to low of octane. Could this be because in where the car is from, in Kentucky, they dont have 85 octane gas. I have been using 85 and 87 since i got the truck in November, and filled up with 85 and the engine light on the way back from Canyonlands and check engine light came up shortly afer. If anybody lives in CO what gas do you use?

 

[fourwd1]

What octane grade does the truck require?

 

[fourwd1]

And more than likely it's the altitude.

 

[turbodudey2]

I lived up in Lake City (just south of Gunny) for several years, and always used 85 octane in the 4ruunner. Never had any problems. At that altitude the PCM should be happy with 85. You might try resetting the PCM if it's not used to the altitude...

 

[Burt]

As per the manual, I use 87. Haven't had a problem.

 

[Jeff Kleb]

85 Octane


Oh wow! Where in the heck can you find 85 Octane fuel? All we have here is 87, 89 and 92 (or sometimes 93, but it is rare).

I think 85 Octane gasoline would make my engine ping like a Jamaican steel drum, especially in my V8 Silverado!

 

[bluebullet]

The higher the altitude the lower the octane required to avoid pinging. Many refiners make 85 (R+M)/2 for high altitude areas in CO. Every penny saved is a penny earned.

 

[Jeff Kleb]

The higher the altitude the lower the octane required to avoid pinging. Many refiners make 85 (R+M)/2 for high altitude areas in CO. Every penny saved is a penny earned.

Oh, okay. I suppose it is because of the air being thinner. Makes sense, I suppose.

Here in VA, we have 87, 89 and 92 (sometimes you can find 93) as our choices for unleaded. However, all of our gasoline has 10 percent ethanol added to it. While I don't think it harms the anti-knock qualities of the fuel, ethanol does cause a slight decrease in fuel economy -- probably because ethanol mixtures (E10, in our case) have a lower BTU content than does straight gasoline.

I read a news story that the EPA is pushing for E15 gasoline along the East Coast; which would be harmful to older cars and small engines (lawn mowers, motorcycles, etc.). Damn corn lobby!

Ethanol belongs in my liquor cabinet, not my gas tank.
:AK47:

P.S. Next time I am up in the mountains (WV, MD or PA), I will look to see if they offer 85 Octane gasoline. I'll probably not be buyin it, though, as it will run rough when I come back down to sea level.
:hunter: