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IT_S8

A8 Parts LPG Conversions

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When cold starting on petrol typically how long/far is it before it switches over to LPG?

Depends on the outside temperature / temperature of the engine. On a winters morning with frost I have to do about 1 to 2 miles until the temp gauge is showing about 30. On a hot summer's day I am hardly out of my drive. If the engine is warm it's instant. :)

To add another dimension, you should not keep petrol in your tank for more than 3 months as it goes stale. That would happen if I filled up my tank and ran just on LPG as I do normally. So all I do now is keep a quarter of a tank (just enough to keep the warning light off) and top up petrol whenever the light comes on.

Mike

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Thanks, that's answered one of my main concerns.

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I should add that I occasionally run a full tank of petrol through the engine. On a long journey or something just to keep the injectors clean and working. Redex or injector cleaner helps.

Mike

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When cold starting on petrol typically how long/far is it before it switches over to LPG?

As per Mikes rather concise answer, its down to the coolant temperature really. It can be as quick as a mile or so in summer, or a couple of miles in winter time. Once warmed through, a warm start will see the LPG switch over very quickly. Whilst it does use a little of the petrol it is good to keep things moving, uses the petrol injectors and keep the petrol turning over. Mike is right, petrol can go a bit stale so just pop a little bit in every once in while with the LPG fill rather than keeping it full.

Keeps the weight down for a bit more economy too +++

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Hi Guys,

Sorry is this is off topic a bit but I have a strange LPG related question.

On my 4.2 D3 I normally get about 17.5mpg running on LPG. Normally I have the gearbox set to drive and the suspension set to automatic.

Recently I have kept the gearbox set to drive but set the suspension to dynamic. For some reason this has increased my LPG mpg to nearly 20. I was under the impression that changing the suspension will lower the car so may have a small effect on the wind resistance but this is a near 15% improvement in economy which seems far too big a gain to have come from lowering the car.

Any ideas why? Does the A8 run a different engine map in dynamic mode? Perhaps the LPG ECU was "tuned" to that mapping?

Thx

Alan

PS I am pretty confident in the figures as I always set the trip counter to zero after I fill up. That way I know how many litres of LPG I have used to cover the distance on the trip counter. I always fill up at the same place and only use the car for going to / from work. I have alternated between the different modes a couple of times now.

PPS On the D3 its possible to fit the LPG filler next to the petrol filler so its all hidden away under the fuel filler cap. Not sure if this is the same on the D2 but would recommend anyone fitting LPG checks as it makes for a neat install.

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PPS On the D3 its possible to fit the LPG filler next to the petrol filler so its all hidden away under the fuel filler cap. Not sure if this is the same on the D2 but would recommend anyone fitting LPG checks as it makes for a neat install.

No room on the D2 unfortunately.

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For those like me who are researching LPg conversion , i found this piece of interesting info on lpg duty and plans government have declared.

The Government continued to demonstrate its long term commitment to LPG in the 2008 Budget when the Chancellor announced a continuation of the existing guarantee for low fuel duty for LPG through to 2011. The duty will rise by no more than 1p per litre per year more than petrol or diesel. The rates announced are:

  • The fuel duty increases planned for the 1st April will now take place on 1st October 2008. At this time duty on LPG will increase only by .135p per litre more than petrol/diesel.
  • As previously announced, on 1st April 2009 fuel duty on LPG will rise by .035p per litre more than petrol / diesel
  • On 1st April 2010 all fuel duty rates will increase by .5p per litre plus inflation. As a result the specific duty rate will not be known until then.
  • This means that the price of LPG at the pumps should continue at around half the price of petrol and diesel for the foreseeable future.

Has anyone heard of any changes to this, or does it still apply?

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