jim1000

My 1999 4Runner SR5V6 knocks when I use 87-octane. Question for Toyota: Shouldn't a $30+k car have a sophisticated enough knock sensors to be running efficiently on 87-octane gas without knocking?

As an aside, California gas stinks -- we only get 91-octane for premium; back East, I know Sunoco even sells their Ultra grade with 94-octane. In California, gas stinks, but the weather is nice.

What types of grade of gas are other forum members using?

mam4994

On my Heep Grand Cher. it would start knocking and what I always did was put 91 octane in for a couple fills, put 87 octance back in and it was good for about another 15,000 miles.

I don't know if this a great fix or if it is okay for the engine, but it worked on the Heep and it is still going strong.

Maybe someone has a better fix?? But that has been the only car I ever owned that knocked.

UNR.Grad

My old Ford Exploder used to knock on 87. I just upgraded to 89 and it went away for the most part, sometimes when going up a hill on the freeway it would have a slight knock. On 91 it never knocked.

Rick F.

I'd check the plugs and timing and run a fuel system cleaner once or twice through the tank. Are all your vacuum lines in good shape? Does it happen with different brands of gas?