Rattling sound at 1500rpm to 2000rpm

[Isamu]

Help! I have a 1.6L protege, auto, that is making a rattling noise when i accelerate. It happens at only around 1500rpm to 2000rpm. I had it sorted out once when I had her serviced, the mechanics sprayed some stuff into the spark plug holes and "cleaned" some crap out. They suggested I use a certain brand of petrol...saying it was the "cleanest". The sound went away.

BUT, it's back! and I have no idea why. Can anyone tell me why it makes that noise? I have noticed that many autos (the older ones) on the roads, have the same sound when they are accelerating, just for a short while, or when going uphill.

Any advice would be great!

Thanks.

 

[Isamu]

errmmm, anyone?

 

[TheMAN]

umm... use premium fuel?

 

[NegatiZE]

Your car is pinging. Use higher octane fuel like TheMan says.

1.6's don't have knock sensors to retard timing when running crappy fuel.

 

[Isamu]

I currently use 95 unleaded, there's a 98, so you're recommending I use that?

 

[TheMAN]

the owners manual recommends premium unleaded, so that's what you should use

 

[Isamu]

well, had the engine flushed today, sheesh! didn't know that such gunk could build up inside, got new plugs too..seems to have done the trick for now