Why guys, I have a question about gas, I'm currently running 87 through my cherokee, and was thinking about changing to 89 or 91, is this a good idea, or will it cause problems?

 

What is making you want to change?

 

It's losing power, and a couple people suggested that running better gas through it could help the problem

 

Won't hurt anything. You can even put 98 in there. Might give you a slightly better mls/gal (have to do the maths if that gives you a benefit or not in regards to increased fuel price). Unsure if it makes a significant power difference though.

We don't even have the 87 here in Oz, lowest here is 91. Although it will run on it, I wouldn't advice to poor in the 10% ethanol variant though.

 

it wont make a difference unless its pinging or knocking. the ECU is tuned for 87, and will not adjust timing to be more agressive with higher octanes, which is what would give more power. Keep the 87, from a decent station.

 

That's all we have in the US (courtesy of uncle EPA), we have so much food we burn it.

 

It has been knocking a little bit, but it's got 270,000 miles, so that's kinda expected

 

if youre down on power and have that many miles, whens the last time you changed the plugs?

 

I haven't since I bought it 5 months ago, do you think that's something I should try?

 

well they call for replacing them every 30,000mi, and unless you believe the previous owner did them recently.... replace them with champion coppers.

 

Unless u have a glove box full of recent maintenance receipts, presume the PO did nothing and get started. Also, Google octane myths......some have already appeared in this thread.

 

I run 91 just because pretty much every station around here (southeast Iowa) has ethanol in all but the "premium". That's the price of driving a Jeep in the land of corn. I have to pay extra to avoid it.

 

New NGK plugs, Napa cap, rotor and wires.

Click on the pink link below and do posts 1,3,4, and 5. Report back when done.

 

This x100 lol

My 91 had no trans fluid in it. I bet you plugs are nasty. Might as well go for the whole tune up.

 

Why would premium not have ethanol as well?