Wrong Octane Fuel

[KiwiGuy]

The dealer I bought my 2005 Seadoo RXT said I would be fine with standard fuel (91 Octane here in NZ) but under power I got a CHK ENGINE message on the dash. I only ran it for a few minutes on the learners key (too slow!) and a few minutes on normal key.

The dealer says it's a "Knock sendor " issue and has replaced it and is putting high octane fuel in (we can buy 98 octane here).

Would this have damaged my engine?
It's under warranty but I'm hoping all will be OK.

 

[Dr Honda]

If your boat is supercharged… you need the higher octane fuel.

Over there… you can’t compare your numbers to the numbers we use in the USA since they are not calculated the same way. As I recall… you will use RON numbers… and they are much higher than the USA numbers.

OK… if you are running low octane fuel… while under boost, you can have preignition, and “Knocking.” Knocking on a water cooled, normally aspirated engine can cause problems… but normally is just annoying. On a boosted engine… you could break the piston crown, melt the piston, crack the rings, mash the wrist pin and main bearings, or blow the head gasket. So yes… if the dealer says the warning light was the knock sensor… you could have caused problems. I would put in the highest octane fuel you can find, and drive it around at low throttle settings until you’ve burnt at lest half a tank of fuel… then top it off again with the proper fuel. You should be good then. (if your engine is ok now)

One of my favorite sayings from an Ol’ School racer here in the states, by the name of Bernie Bergman, who liked boost from a turbo is… “By the time you can hear preignition under boost… it’s like hitting the top of your piston with a 10Lb (4.5Kg) sledge hammer has hard as you can.”

Good luck