2012 Forester 3011DS V10 spark knock

[Mach428]

Has anyone had a problem with pre-ignition (spark knock) and what did you do for a remedy. I can't believe Ford expects us to run premium fuel. I use Shell so it's not like I use cheap fuel.

[grumpy0374]

Running premium is a waste of money. The V-10 and it's computer was made to run on good ole 87 octane. Anything else is useless.
Your spark knock may be due to a plug going bad or a coil-over-plug going bad.
Posssibly a sensor going bad.
35,000 miles on our 2012 Lexi V-10, and have always used 87 octane. Never a miss, never a hic-up.
Grumpy

[Kenny kustom]

87 is all you need.

[RamblerGuy]

I agree with the previous posts. If you have spark knock something is wrong. Have someone check your codes.

Here's a thought:

Have you had spark knock long? If it just started, is it possible you got some fuel with diesel in it? It's possible some could have been mixed in the gas, like if a tanker's compartment wasn't completely emptied and it was used for unleaded the next load. Does it run okay? If it surges or is down on power, you could have some diesel in your tank.

[benagi]

I've even run 85 octane from Costco and haven't had spark knock.

[Mach428]

Thanks for the ideas folks.

It's been doing it for a while so I know it's not something like diesel. I've refueled in many states. I can usually work the gas pedal to avoid it but that's a pain in the butt. I've worked on cars all of my life and have found the main culprit to be timing too far advanced, but the timing on these engines are set by a computer. I've also read that a spark knock sensor was not used in 2012

[bob caldwell]

Lean condition...check EGR system...

[Mach428]

But that too is controlled by the computer and would set a code, would it not?

[bob caldwell]

You have a code reader?.....Auto zone does.....will give you a nice free read out.....

[markb422]

Like my Scan Gauge. Use it to scan codes if needed or mounted on column for continuous readout of four parameters.

[A32Deuce]

If it is spark nock, it should throw a code!