pinking under load

Hi all
after some advice please

Got a d2 v8 lpg and its started 'pinking' under load. not a misfire as such but you can hear the pinking mainly from 2k rpm to 3k.
I have done a search and get everything from bottom end to inlet manifold.
the leads and coil packs are 8000 miles old
the plugs are 4000 miles old
the maf (bosche)and air filter are 1000miles old .

I am probably going to put new plugs in anyway as a starting point (the original champions only lasted 3000m)the ones in there now I 'invested' in some platinum iridium gold plated recommended by everyone super dooper 20000mile plugs so we'll see what they are like.

strange thing is that if I stop for 5 mins and they restart the engine doesn't 'pink' at all for about 10 mins after then comes back

does it on petrol and lpg
if i boot it and push through 3000rpm it seems to clear and stops pinking (it is difficult to hear though)
fuel economy is about the same , I've just come back from the lake district and I got about 12 mpg round the hills and twists of the lakes and 15mpg fully loaded with a roof box on the m/way at 65-70 mph
hopefully someone will say they have had the same and give a pointer.
Cheers
Andy

Fit LPG compliant plugs, they are much more suitable as they are stronger and built to withstand hotter temps and 'dry' running. Check your plugs for hairline cracks in the ceramic, or soot around the base - this is usually due to plugs overheating on LPG powered vehicles. It would also cause an arc - but would or should cause a misfire, though in a V8 you may not notice as it is subtle rather that obvious.

I would also look at the lambda sensor and check that both circuits are working ( one circuit for cold running, one for hot) It could be the hot circuit has failed, which is why the problem disappears when cold/restarted after a while, as the lambda would revert back to the cold circuit for a set time.

Check that your LPG software is up to date, may pay to get that serviced - and also check the ECU on the landrover. There have been reported probs on the ECU of the D2 with water or oil ingress - or even just a dry joint. That should, as with the lambda, come up on diagnostics.

As you have replaced most of the other culprits - I would check these out.

thanks for reply auto.
I should have mentioned the lambdas were replaced 8000miles ago as well and the plugs were meant to be a hotter grade for lpg.
of course with it being a landy then premature failure of all / any of these items is a possibility
Andy
A diagnostic would be a geat start but I begrudge paying dealer prices and dont know anyone local with kit

It's probably running a bit lean in the midrange if it's pinking. Then after a restart it might be adding more fuel, preventing it. Perhaps.

Also, top end the ECU pours fuel in, for protection.

Could also be an air leak, or ignition timing.

Everything you have fitted brand new etc should mean the engine is in good working order, my guess is something working incorrectly as opposed to not working at all.

Needs to go on diagnostics, to check injector timings and duty cycles ( does the pinking stop when the duty cycle increases), check ignition timing (does the pinking stop when the ignition advances?)

hopefully if you can find the fault on petrol it will either solve it on gas, or then go to a gas specialist for adjustment on the LPG side.

And there MUST be a LR specialist near you somewhere!!

Cheers, sam