Is this possible?

So about 2 months after I first got my 2004 ranger I noticed engine knocking during acceleration. I started putting 89 octane fuel in and the problem persisted…I upped it to 91 octane (sunoco) and the problem seemed to go away. Yesterday I was driving my brother to the airport and lo and behold…engine knocking…I’m wondering if it’s something else. It only does it when Im accelorating up hill. I just thought 91 octane would put an end to it.

its not like im driving a high performance vehicle or something, the manual says 87 octane

any thoughts?


I dont think it has anything to do with the octane, and you should bring it back to the dealer before you touch anything.

Visit the dealer. It’s under warranty, no?

my old ass 89 does that too,I throw 93 in and it stops.

Yeah 2004 should be under warrenty unless your over mileage

i got 2k left before warantee’s up :slight_smile:

to the dealer!



I found something interesting out

my truck has a compression ratio of 9.7:1

wouldn’t that require a higher octane fuel than 87? I was under the impression that 87 octane should not be used in vehicles with compression ratios of 9.3:1 or higher?

I just don’t wanna go in bitching about knock and have the guy say “fucker, of course its knocking on 87”

the 91 still doesnt make sense though.


manual says 87. Thats false advertisement

good point.