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View Full Version : LPG Backfiring.


sam_d
29th December 2007, 07:07 PM
Can someone please explain (in fairly layman terms) the following:

What causes an engine to backfire?
What actually happens when it backfires?
Can it cause damage/what severity?

Cheers!
PhilipA
29th December 2007, 07:37 PM
There are two types of backfire.
1- caused by unburnt fuel being burnt in the exhaust. Big bang, muffler blown off etc etc. usually caused by intelligent person turning ign on and off or leaking exhaust valve.
2- backfire( or should it be frontfire) , of fuel in the manifold. Usually happens with old vacuum style LPG when the manifold is full of LPG and somehow a cylinder fires (maybe crossfire)with an inlet valve open, or leaking.
Results can be spectacular, with air cleaners blown to bits, MAFs and flapper sensors destroyed. Can be very expensive because of the expensive nature of electronics.
Regards Philip A
sam_d
29th December 2007, 08:22 PM
2- backfire( or should it be frontfire) , of fuel in the manifold. Usually happens with old vacuum style LPG when the manifold is full of LPG and somehow a cylinder fires (maybe crossfire)with an inlet valve open, or leaking.
Results can be spectacular, with air cleaners blown to bits, MAFs and flapper sensors destroyed. Can be very expensive because of the expensive nature of electronics.
Regards Philip A

So...could this result in a fire in the air filter box on a Disco 1 fitted with an LPG kit (one of the older types) moments after a loud bang coming from the engine area?
PhilipA
29th December 2007, 08:24 PM
YES.
Regards Philip A
abaddonxi
29th December 2007, 08:32 PM
Didn't happen without pics.:(

That doesn't sound good.

Cheers
Simon
sam_d
29th December 2007, 08:32 PM
YES.
Regards Philip A

Thanks for the info!

I was trying to decide who to call first - my insurance or the LPG fitter who did a check up and tune less than a week ago.

Oh, BTW, I my air filter caught fire today...
sam_d
29th December 2007, 08:38 PM
Didn't happen without pics.:(

That doesn't sound good.

Cheers
Simon

No pics (I didn't wanna rummage around for me camera at the time) but it certainly did happen :(
abaddonxi
29th December 2007, 09:01 PM
I heard a big bang, thought it was someone ripping off the pub next door.:D

Could be a while before that steering damper settles in.

Cheers
Simon