but only on gas , and as soon as it gets going it fine , and ticks over ok too
if i switch to petrol it ok on pull away ??
it's been ok before just started doing it tonight
spluttering on pull away on LPG
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i found out what the problem was ....
it broke down completely on me yesterday ...i thought it was the ignition module
but it back fired the other day when i chnged over from petrol to gas , and you guessed it hadn't got round to fitting the blow back thingy yet
the whole bottom of the airflow meter was hanging off ...
that'll teach me .... lots of instant gasket and pop rivets and it's fixed , i cna't belive they are just held on by silicone , no fixing at all
it broke down completely on me yesterday ...i thought it was the ignition module
but it back fired the other day when i chnged over from petrol to gas , and you guessed it hadn't got round to fitting the blow back thingy yet
the whole bottom of the airflow meter was hanging off ...
that'll teach me .... lots of instant gasket and pop rivets and it's fixed , i cna't belive they are just held on by silicone , no fixing at all
remember it's only a bodge if it DOSN'T worK
-
Dangerdoc
AFM
hi Bodger,
There is a technique that can be employed to save AFM's from being destroyed.
Chirs Perfect components did the flap opener that was all good and well but had a habit of sticking open and when on petrol you could be forgiven to think that the car was running on coal with the amount of smoke from the exhaust.
Well the guys at RPI engineering are recommending that you open the flap and hold it open with a grub screw running constantly on LPG. I quizzed them on the fact that the car needs to start on petrol and then switch over.
The thing is that a vapouriser needs really to heat up as in winter there is a real risk of it freezing and that is another story but they say there is no problem.
The AFM issue is long standing - especially the damn flapper ones as they are very very sensitive to backfires.
We do know that the backfire valves are pretty crap in many ways and they add additional resistance to the airflow inlet. Look at the diameter of the inner orifice when the flap is open and you will see it is kind of small.
Then again most flat type venturi mixers are tiny as well.
The air induction pipe jubilee clips should be loosened but get a BIG cable tie and wrap it around the damn inlet flexible pipe as if you get a backfire again and are whizzing up some busy road the last thing you want to do is to have to walk back in the piddling rain and dark looking for a short black pipe - not good (been there - done that).
The other thing, - scrap the flat type of mixer - get yourself one of the 72mm jobbies or equivelant size that sits by friction fit (very tight) into the plenum inlet neck. This allows for a larger diameter of mix, better venturi effect and also - most importantly - MUCH LESS gas mix that is ready to go bang and destroy that little flap doodah.
I have deliberately extended the distance from the plenum chamber to the AFM and moved all sorts of gear out of the way so that the AFM is a good bit away from the plenum chamber, have a 72mm diameter mixer at the plenum and no backfire valve.
Popper valves are a reasonable idea - fix them directly onto the chamber as they are better than the backfire flap doodah.
Well that's about it for now. Hope that helps.
There is no reason to keep the air intake assembly the same as the manufacturer likes it, indeed I am considering a pre-plenum box with four popper valves in it between the main plenum and AFM to add an extra level of protection.
Oh - you spark leads MUST be of a high quality and your plugs MUST be correctly gapped and very clean. Sorry if that is the ol' suck eggs thing but you will be surprised how many sub-standard ignitions are out there with shitty plugs and leads. One tiny mis-timing event and BANG - out with the silicone and gaffer tape.
Doc
There is a technique that can be employed to save AFM's from being destroyed.
Chirs Perfect components did the flap opener that was all good and well but had a habit of sticking open and when on petrol you could be forgiven to think that the car was running on coal with the amount of smoke from the exhaust.
Well the guys at RPI engineering are recommending that you open the flap and hold it open with a grub screw running constantly on LPG. I quizzed them on the fact that the car needs to start on petrol and then switch over.
The thing is that a vapouriser needs really to heat up as in winter there is a real risk of it freezing and that is another story but they say there is no problem.
The AFM issue is long standing - especially the damn flapper ones as they are very very sensitive to backfires.
We do know that the backfire valves are pretty crap in many ways and they add additional resistance to the airflow inlet. Look at the diameter of the inner orifice when the flap is open and you will see it is kind of small.
Then again most flat type venturi mixers are tiny as well.
The air induction pipe jubilee clips should be loosened but get a BIG cable tie and wrap it around the damn inlet flexible pipe as if you get a backfire again and are whizzing up some busy road the last thing you want to do is to have to walk back in the piddling rain and dark looking for a short black pipe - not good (been there - done that).
The other thing, - scrap the flat type of mixer - get yourself one of the 72mm jobbies or equivelant size that sits by friction fit (very tight) into the plenum inlet neck. This allows for a larger diameter of mix, better venturi effect and also - most importantly - MUCH LESS gas mix that is ready to go bang and destroy that little flap doodah.
I have deliberately extended the distance from the plenum chamber to the AFM and moved all sorts of gear out of the way so that the AFM is a good bit away from the plenum chamber, have a 72mm diameter mixer at the plenum and no backfire valve.
Popper valves are a reasonable idea - fix them directly onto the chamber as they are better than the backfire flap doodah.
Well that's about it for now. Hope that helps.
There is no reason to keep the air intake assembly the same as the manufacturer likes it, indeed I am considering a pre-plenum box with four popper valves in it between the main plenum and AFM to add an extra level of protection.
Oh - you spark leads MUST be of a high quality and your plugs MUST be correctly gapped and very clean. Sorry if that is the ol' suck eggs thing but you will be surprised how many sub-standard ignitions are out there with shitty plugs and leads. One tiny mis-timing event and BANG - out with the silicone and gaffer tape.
Doc
thankyou Doc , as you can see from my picture it NOW has one of those , flappy backfire stoppers ( the silver/orange ring ) , i had it sitting there for a while but it backfired before i fitted it ...that'll teach me ..lol
oh and i don't care what RPI say , it does freeze when starting on gas when it's a bit cold outside ..been there done that , and it's amazing how much hot water poured over the vaporiser it took to thaw it ..loads
even the water in the coolant hose froze
luckily mine is not all about power as it fitted in an LDV400 campervan so i don't really find that the restrcition is not really a problem , and it does 15 mpg on gas not too bad as it's about as slippery as a brick ..lol
what is useful to extend the inlet tract is the 62mm drain pipe fittings ( guttering fittings , black or brown ones) , if you warm the plastic a little they push on both ends of the airflow meter ,and then you can just fit how ever much pipe you fancy to it , 3mtrs if you want ..lol
oh and i don't care what RPI say , it does freeze when starting on gas when it's a bit cold outside ..been there done that , and it's amazing how much hot water poured over the vaporiser it took to thaw it ..loads
even the water in the coolant hose froze
luckily mine is not all about power as it fitted in an LDV400 campervan so i don't really find that the restrcition is not really a problem , and it does 15 mpg on gas not too bad as it's about as slippery as a brick ..lol
what is useful to extend the inlet tract is the 62mm drain pipe fittings ( guttering fittings , black or brown ones) , if you warm the plastic a little they push on both ends of the airflow meter ,and then you can just fit how ever much pipe you fancy to it , 3mtrs if you want ..lol
remember it's only a bodge if it DOSN'T worK
I fitted my mixer to the plenum inlet hole, and also have a flap-opener. I've suffered a couple of backfires (caused by very lean mixtures), and it's not done any damage........
Also, my Landie only runs on LPG, and I've never had the vapouriser freeze up. Well, the only two times where when I hadn't primed the coolant properly.
Chris.
Also, my Landie only runs on LPG, and I've never had the vapouriser freeze up. Well, the only two times where when I hadn't primed the coolant properly.
Chris.
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Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8
