Pinging noise

Hello.I have a 2000-2001 4.0L SE P38 Rangie.When accellerating,there is a pinging sound from the engine,sounding as if my car is a diesel.Also,my car looses power and i must drop back so as it can 'catch' up.Have put higher octane fuel,but to no avail.By the way,the car starts with no prob's and no sparking from the ignition leads....Any ideas?

Well it most definitely isn't your windscreen wiper motor...

Preignition is due to over advanced ignition timing, or hotspots developing in your engine. How many miles, and when was the timing chain last changed? Is it a hardened duplex timing chain or standard?

I'd look at this first, maybe check the timing marks with a strobe to see if anything is way out, then start looking at the expensive options...

Hello,and thanks for your reply.The car is nearly up for its 80,000km service,which i believe is when the timing belt is changed.The belt looks quite thick,which i hope answers your question...I'm a bit of a novice.