Any LPG Gurus care to give some stab in the dark random advice.

EFI or natural ? Mine struggled until we changed the restriction on the air inlets - with some panscrubs.

Steve

Efi, which had until today, a small very ragged mesh and foam (patches without foam) cone filter. As I don't have the original air box, I had to replace it with another cone. I went for one with a much finer metal mesh this time. Money is tight, and until I know what the MOT will cost me, I'mnot banking on spending lots on replacement parts until they are needed so hunting down an air box is out.

So, where did you place the scrubs? before or after the flapper, and how did you secure them into the inlet?

Sounds like there's a vacuum issue, not with the engine itself but how it's sensed at the vapouriser. Where is your mixer fitted? If it's on the throttle body of the plenum then this is exactly what happens with a flapper setup unless you fit a vacuum-operated flap-opener device. The alternative is to fit a mixer which bolts onto the front face of the flapper, behind the inlet pipe casting. Badger.

Yes, it is on the plenum. It has no flap opener. Guess that might be my issue then, or at least part of it.

It is a little flat when on gas, but I'm putting that down to the ignition timing still being timed for petrol.

There is uk.rec.cars.fuel.lpg - maybe worth a try, apologies if you already have!

Julian.

alternative

Then that is definitely the issue. Either change the mixer for the type mentioned or fit a flap-opener device. Badger.

That was my first port of call, but the tumble weed blowing past dragged my here :)

Seems to have gone a bit dead in there.

I've seen somewhere that people have fitted balance pipes between the atmospheric vent on the back of the vaporiser and the back of the AFM.

As the vacuum is created in the vaporiser it opens the flap. I think.

Trust me, it's a fudge that doesn't work correctly, especially under rapid throttle openings, leading to backfires! Fit the correct mixer or flap opener and it'll be fine. Badger.

On or around Sun, 15 Apr 2007 11:14:43 +0100, Elder enlightened us thusly:

You can do that, so that the vapouriser uses the pressure in the inlet tract as a reference rather than normal atmospheric.

You need an anti-backfire thing, too, if you do that, or you can blow the AFM apart.

On or around Sun, 15 Apr 2007 18:59:29 +0100, "Badger" enlightened us thusly:

The sierra 2.8 seem to work OK like that. no more backfires than any other thing I've had.

Yeah, I see that.

The proper flap opener things aren't cheap though are they.

Proper mixer is fairly cheap though.

With respect Austin, the v8 has a considerably larger "air" volume within the inlet manifold/plenum/ducting than the 2.8 - it's this volume that causes the sudden weakening or richening due to sudden throttle movement and it's the weakening that causes the backfire. Why fudge the installation and create potential for problems (especially considering the cost of flapper-type afm's) when it can be done right at reasonable cost in the first place? Badger.

All the ones I've seen have been plenum mounted though, don't think Ive ever seen a mixer that sat in front of the air flow meter.

Go to

That's the item you require.

;-)

Thanks. Was just looking for such a thing.

--=20 Carl Robson Audio stream:

Any reason why this flap opener

Manifod vaccum fed, via a solenoid valve to switch the vacuum as you change over onto gas. Will work with any vapouriser, they just want to sell you one! (Admittedly, one of the best there is for a vapourmix lpg system!) Badger.