Jingling noise on hard acceleration

Sounds like it's pinking (predetonating).

Has it been doing this long? Have you done anything different recently (like changed fuel)?

Yes, it's been going on for a few months. Haven't changed any fuel octane.

Still sounds like pinking ;-)

Have the plugs been changed recently?

Yes, About 9k miles ago at the 30k major service. What additive do you recommend to clean the fuel system and boost octane for a tank of gas?

If it was a c900 - I'd be checking the timing.. If the timing can be adjusted on a 9-3 - see what happens if you step it down a notch - also - check your air filter and whatever they are using for an air mass sensor in that rig..

Now - I must go back to work.. All nighter here I'm afraid..

J Dexter - webmaster -

You shouldn't need any additives - not at this stage anyway. None of my 200k mile + cars ever have.

As Dexter says, it may well be a timing issue. But I don't think the timing is adjustable on your car - you need to fiddle with the ecu mapping for that.

Before you take it into your favourite mechanic, try some octane booster - use a generous dose (as per bottle lable) and see what happens. They're all very similar, so just buy whatever is handy. I will probably say "octane booster" on it.

There is also an outside chance it's not pinking, but something loose under the bonnet. Take a good look, particularly at the heat shield over the exhaust manifold.

My memory could be way off, but I recall reading in my factory service manual something about a 'Hall' sensor or some such that might have something to do with pinking.