Backfiring

smurphy · Feb 19, 2009

I've change the plugs, leads and dizzy cap on my disco and since it backfires when starting. It only does it when the engine is cold and only 2-3 times once Ive rev-ed it its fine. It starts pretty much straight away so it not turning over and over to cause this. Its a 1995 3.9 V8 with LPG fitted but I'm starting and running in petrol for a mile or two before switching to gas.

Thanks in advance Steve

Cabbie · Feb 19, 2009

The ignition timng could be a tad too far advanced.

Soloby Rob · Feb 19, 2009

When you say 'backfires' are you saying it actually goes with a loud bang out of the exhaust.

smurphy · Feb 20, 2009

Soloby Rob said:
When you say 'backfires' are you saying it actually goes with a loud bang out of the exhaust.

No it pops and bangs at the front end out of the air filter and some times it pops at the exhaust. I got rid of the air box and fitted a K&N a couple of months ago but way before the leads n plugs. The reason I put the K&N on was it backfired when the gas was low and destroyed the air box and the M.A.F. and it seemed a better option as they are more free flowing.

deadlight · Feb 22, 2009

have had the same problem,have now fitted a backfire valve on my 93 disco 3.9 but problem can occur if any of the ht leads touch the engine,also check that the hose between plenum and airflow meter does not have split in it,this is a common one,also check that engine breather comes in before the lpg distributor not after it if single point injection.Also do not use platinum spark plugs-lpg eats them!!hpe this helps DEADLIGHT

demitrious1973 · Feb 22, 2009

are they the right plugs and leads

smurphy · Feb 22, 2009

deadlight said:
have had the same problem,have now fitted a backfire valve on my 93 disco 3.9 but problem can occur if any of the ht leads touch the engine,also check that the hose between plenum and airflow meter does not have split in it,this is a common one,also check that engine breather comes in before the lpg distributor not after it if single point injection.Also do not use platinum spark plugs-lpg eats them!!hpe this helps DEADLIGHT

thanks for the trys I'll get on to looking into all of them tomorrow regards Steve.

CharlesY · Feb 23, 2009

Very lean mixture is a prime cause of engines spitting back into the inlet manifold.

CharlesY

Backfiring

smurphy

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Cabbie

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Soloby Rob

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deadlight

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CharlesY

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