Hi All 
I have ford Galaxy 2.3 1999 its LPG/Petrol the system is a single point 
emmegas, when pulling away from standing start on LPG if the engine labours 
or I try and accelarate to fast it backfires but if i'm a bit more gentler 
on acceleration its ok when it gets going its fine taken it on motorway it 
drives great has anyone any idea what causes the backfire and how to stop it?

cheers

url:http://myreader.co.uk/gp/1272-1.aspx

"jim holland"  wrote in message 
news:345cb808edc24accbb58f4f211f0ecf6@newspe.com...
> Hi All
> I have ford Galaxy 2.3 1999 its LPG/Petrol the system is a single point
> emmegas, when pulling away from standing start on LPG if the engine 
> labours
> or I try and accelarate to fast it backfires but if i'm a bit more gentler
> on acceleration its ok when it gets going its fine taken it on motorway it
> drives great has anyone any idea what causes the backfire and how to stop 
> it?
>
> cheers
>
> url:http://myreader.co.uk/gp/1272-1.aspx

Could be a weekness in the ignition system, changing plugs and leads may 
cure the problem. Emmegas systems aren't the best unfortunately, my previous 
car had the same system, & even with new plugs and leads, it was still prone 
to the odd backfire.

On Sun, 18 May 2008 21:37:58 +0100, Dave Griffs wrote:

> "jim holland"  wrote in message
> news:345cb808edc24accbb58f4f211f0ecf6@newspe.com...
>> Hi All
>> I have ford Galaxy 2.3 1999 its LPG/Petrol the system is a single point
>> emmegas, when pulling away from standing start on LPG if the engine
>> labours
>> or I try and accelarate to fast it backfires but if i'm a bit more
>> gentler on acceleration its ok when it gets going its fine taken it on
>> motorway it drives great has anyone any idea what causes the backfire
>> and how to stop it?
>>
>> cheers
>>
>> url:http://myreader.co.uk/gp/1272-1.aspx
> 
> Could be a weekness in the ignition system, changing plugs and leads may
> cure the problem. Emmegas systems aren't the best unfortunately, my
> previous car had the same system, & even with new plugs and leads, it
> was still prone to the odd backfire.

be careful, I blew a alfa 155 inlet manifold to pieces with an almightly 
backfire one day. a lot of cars now have plastic manifolds as all they 
would normally hold is air. with LPG you suddenly have an explosive 
mixture. Get a blowback valve fitted to protect your wallet.

jim holland wrote:

>  when pulling away from standing start on LPG if the engine labours
> or I try and accelarate to fast it backfires but if i'm a bit more gentler
> on acceleration its ok when it gets going its fine taken it on motorway it
> drives great has anyone any idea what causes the backfire and how to stop
> it?
> 
I think it's to do with valve overlap and flame speed, at full throttle and
low revs (ignition retarded) and if the mixture is weak the exhaust valve
can open while the gases are still above the autoignition temperature of
the mixture. as the gases don't have the inertia they would at high and in
a multi cylinder engine there will be another cylinder during its valve
overlap phase so there is the chance of a flame path from the exhaust
manifold through the fresh mixture in the cylinder and out through the
inlet valve.

At higher revs the natural momentum of the gases in the exhaust scavenges
the system.

I often have the opposite problem where the mixture doesn't fire and carries
through to the exhaust and is subsequently detonated there by the next hot
exhaust stroke.

AJH

Hi,

I have a Ford Scopio with the 2.3 engine and I have had converted years ago,
but it does have an habbit of back firing in the inlet manifold. It only 
does it every
couple of months, more so on cold damp winter mornings.

The back fire manifests its self in blowing out a vent plung at the very 
back of
the inlet manifold. This was a shame as the first time it happened I lost 
the plug
somewhere down the hard should on the M6 one evening and after being towned 
home
and the garage had to machine up a repace plug. Sine then this has been 
firmly
attach to the breather pipe by a juble clip and I have not have any problems 
with
just pushing it back when it pops out.

The car is fitted with a flap value on the air input but the backfire seems 
to be a lot
further in the system and it does not operate.

One theory about why it happens is, it seems to happen when the weather is 
fairly
damp and this dampness could be generateing a static on the plasic inlet 
manifould.

At one time Ford Explorers that had been convered to LPG where known widely
as "Exploders" !!!!!!!!!

Mick



"jim holland"  wrote in message 
news:345cb808edc24accbb58f4f211f0ecf6@newspe.com...
> Hi All
> I have ford Galaxy 2.3 1999 its LPG/Petrol the system is a single point
> emmegas, when pulling away from standing start on LPG if the engine 
> labours
> or I try and accelarate to fast it backfires but if i'm a bit more gentler
> on acceleration its ok when it gets going its fine taken it on motorway it
> drives great has anyone any idea what causes the backfire and how to stop 
> it?
>
> cheers
>
> url:http://myreader.co.uk/gp/1272-1.aspx