Quagmire Posted January 5, 2010 Share Posted January 5, 2010 Well as the title really, has anyone else had a noticeable drop in LPG consumption with the cold? I figured that the vapouriser may be providing a richer mixture in the colder weather until warmed up, but i also thought that the closed loop system would keep a handle on things. However, i can and do start straight from gas even in this cold and so i guess until the lambda is hot i could just be effectively venting my tank through the engine! In the summer/autumn i was getting between 16-17mpg on gas, now its about 13-15 depending on how late i am for work... Could this be the weather, or am i due an overhaul on my vap unit? It hasnt been apart in 2.5 years since i got it... Quote Link to comment Share on other sites More sharing options...
sgnas Posted January 5, 2010 Share Posted January 5, 2010 Entirely different vehicle but running on petrol! My little 1.2 Panda has been doing 53mpg over ~5000 miles I've had it. In the last few weeks it's more like 45-48mpg a 10-15% difference Massive differences to you but overall %age change is similar. Quote Link to comment Share on other sites More sharing options...
disco_al Posted January 5, 2010 Share Posted January 5, 2010 yes, you will notice a difference in the consumption. my old v8 used to use quite a lot more fuel when it was cold. the 300tdi on the other hand has got quicker, mostly due to the cold air on the intercooler. Quote Link to comment Share on other sites More sharing options...
Quagmire Posted January 5, 2010 Author Share Posted January 5, 2010 It runs as normal on LPG, but goes like the clappers on Petrol! Quote Link to comment Share on other sites More sharing options...
mickeyw Posted January 5, 2010 Share Posted January 5, 2010 Well as the title really, has anyone else had a noticeable drop in LPG consumption with the cold? I figured that the vapouriser may be providing a richer mixture in the colder weather until warmed up, but i also thought that the closed loop system would keep a handle on things. However, i can and do start straight from gas even in this cold and so i guess until the lambda is hot i could just be effectively venting my tank through the engine! In the summer/autumn i was getting between 16-17mpg on gas, now its about 13-15 depending on how late i am for work... Could this be the weather, or am i due an overhaul on my vap unit? It hasnt been apart in 2.5 years since i got it... Cor blimey! I'd better get some lighter shoes. My Ninety 3.9 auto doesn't often see the right side of 12mpg I have found too, and heard from elsewhere that LPG consumption tends to be worse in cold weather. Something to do with varying thermal expansion of gas at different temperatures maybe Quote Link to comment Share on other sites More sharing options...
Dave W Posted January 5, 2010 Share Posted January 5, 2010 Most LPG is a mix of Propane and Butane. Propane copes better with cold weather and as a result most suppliers increase the percentage of propane in winter relative to butane to make it more reliable. The downside is that the calorific value of propane is lower than that of butane meaning that you use more fuel to do the same job. It's not unusual to see the price vary in winter too as Propane is more expensive and the increased percentage usually adds 1 or 2p to the cost of the LPG. I always got the feeling this was more noticed with the more local small suppliers rather than the big chains who charge a bit more all year round. If you are one of those that worries about such things, the winter mix of LPG produces less CO2 than the summer mix too (propane produces a lot less CO2 than butane). Air density also plays a part at this time of year too, the colder the air going into the engine the more oxygen is available to burn the fuel so both petrol and diesel engines with a way to take advantage of this (closed loop EFI for example) and increase the fuel accordingly, will see better performance. You'll also see improve petrol MPG anyway as you get more fuel in a gallon when it's colder than you do when it's hot. Quote Link to comment Share on other sites More sharing options...
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