I have a tune set for 91 race tune, and while i was gone i think my parents accidently put unleaded 89 oct.

what do i do?

 

You might get some spark knock, but then again you might not. I don't think it will hurt anything, as long as you don't make a habit of it. The engine has a built in knock detector, and it will pull timing if it detects it, so it shouldn't be a big deal. On the other hand, I don't know if your tune will affect the engine pulling timing or not. That is something you'd have to ask the guy who set up your tune.
If your really worried about it, just reset the tune back to stock, or put an 89 tune in the car until you use up that tank.

 

hmmmmmmmm.....im confused

 

Just don't mash the throttle until you get rid of that gas! If you do, you'll hear the detonation, not good. I've been through this here in AZ with the heat while messing with tunes. Just drive it like it's a Camry until it's out of gas, fill it up with 91 and hammer down!

 

would octane booster be of any help?

 

Yes,

 

what kind?

 

Also, if your car is experiencing pinging, specifically at WOT, then another option is to retard the global timing a degree at a time with your handheld tuner until the pinging goes away.
And then reset it to the original timing when the 89 octane gas is used up, and you fill up with 91 octane again.

 

but will the octane booster help out alittle?

 

A bottle of octane booster raises the octane level by only approx. 1 point when added to a full tank of gas. While this may be sufficient to prevent pinging, it will also cost you some $. But retarding the timing a degree or 2 is free, and you will not lose that much power. Plus, the timing will be returned to its original setting when the 89 octane gas is burned up.

 

retard the timing 2 degrees (as in subtract 2 degrees, or -2 degrees) globally until the gas is gone and then put it back where it was when you put 91 back in

 

i dont no how to do that...i just dont want to mess with anything, umm plus i just bought 104 Maximum octane boost, and put that into my tank but in the long run how do i subtract 2 degrees with the Xcal?

 

DANG!! now that i think of it, it was actually 87 oct. because regular was put in!! **** so now its even worse

 

Xylene or Tolune should work

 

now im hearing that the octane boost i put will ruin my spark plugs!!

 

Your making this way to complicated, just return to stock and finish the tank. I think I got a headache !

 

but i would have to take out my JLT II intake, and put the stock one in...plus the stock intake is alittle dusty

 

Yup. This just must be common knowledge for current/former WRX owners. Go to one of the subie sites to confirm.

 

Get a locking gas cap and hide the key!

 

Don't you have a different tune you could put in the computer? Is the 91 tune the only tune other than stock that you have? just put a lower octane tune in the computer until you run out the gas in your tank.