what octane am I at?

[wickerham]

My new PCM requires 92 octane or above, the old broken one used good ol' 87. So today I ran the tank down to 1/8th or less (I know....just replaced filter too!) and put in $5.00 worth of 93. At $3.19 a gallon that's about 1.57 gallons. Then I ran that down to an 1/8th or less and put in $6.00 of 93. At $2.99 a gallon that's 2 gallon. I finally took it to the 1/8th tank again and filled up with 93, 20.6 gallons worth. It's a 23 gallon gas tank.

Where am I at as far as octane? Math whizzes time to shine!

 

[VK56VD]

~You are good to go at this point.

Which car is this?

 

[wickerham]

1993 Jeep ZJ (grand cherokee)

why?

 

[SecondMonkey]

Why in gods name would you use 92 octane in a 1993 Jeep?

 

[wickerham]

I need to use 92 octane or above because the PCM is tuned to run 92 octane or above. What does the year and make have ANYTHING to do with the current topic?

 

[SecondMonkey]

I'm not entirely sure what the "current topic" is. Go fill your tank with 92 and be done with it. It's not that big of deal. I don't understand what you're trying to do here.

 

[mechtech2]

You can't simply do math/algebra to get your result.
This is because the initial amounts of octane raising additives raise it more than subsequent amounts.

But really, just keep filling it with your favorite fuel, and it will quickly get to the level you want. Right now, you are close enough.

 

[af0h]

Originally Posted By: mechtech2
But really, just keep filling it with your favorite fuel, and it will quickly get to the level you want. Right now, you are close enough.


+1

Some people insist on making things harder than they really are.

 

[postjeeprcr]

Originally Posted By: SecondMonkey
I'm not entirely sure what the "current topic" is. Go fill your tank with 92 and be done with it. It's not that big of deal. I don't understand what you're trying to do here.


I agree, I would say just fill with 93 and be done with it

 

[Kestas]

Even the fuel refiners are lucky to hit within 0.1 octane accuracy.