Just this week there’s been a very noticeable increase in fuel consumed. I’m not talking like full tanks disappearing more a case of I’m using about 1/4 a day but previously it was less for roughly the same miles.
Any ideas for what to look at? Could it be because it’s cold? Weight carried has been similar day by day and all gauges including turbo are reading fine. It’s also half way through it’s service cycle so it’s not way out of dock or anything.
toonsy:
Just this week there’s been a very noticeable increase in fuel consumed. I’m not talking like full tanks disappearing more a case of I’m using about 1/4 a day but previously it was less for roughly the same miles.Any ideas for what to look at? Could it be because it’s cold? Weight carried has been similar day by day and all gauges including turbo are reading fine. It’s also half way through it’s service cycle so it’s not way out of dock or anything.
What you driving, what load & weights etc
Could be something simple like tyre pressures the cold weather does change them a company I worked for had their fleet running with nitrogen filled tyres.
Could be the pre filter in the air intake that’s clogged.
Colder Air = Denser Air = More oxygen to be burnt = lean burn = hotter burn
Computer sensors in the exhaust will realise this and inject more fuel to keep exhaust gases lower, so the air-fuel ratio is adjusted back to optimal by the computer. If it didn’t do this, the engine could run lean and hotter, which could cause you big problems.
That’s how it works for turbo charged petrol engines anyway - not sure on diesels, I would assume it’s something similar
Grumpy Dad:
toonsy:
Just this week there’s been a very noticeable increase in fuel consumed. I’m not talking like full tanks disappearing more a case of I’m using about 1/4 a day but previously it was less for roughly the same miles.Any ideas for what to look at? Could it be because it’s cold? Weight carried has been similar day by day and all gauges including turbo are reading fine. It’s also half way through it’s service cycle so it’s not way out of dock or anything.
What you driving, what load & weights etc
Could be something simple like tyre pressures the cold weather does change them a company I worked for had their fleet running with nitrogen filled tyres.
Could be the pre filter in the air intake that’s clogged.
Tyre pressures is unlikely because we have to drive over a pressure sensing plate which pings up warnings if the PSI is outside a certain tolerance. Running Scania btw. Never normally near the weight limits (It’s normally foam insulation boards) as the loads have been bulky rather than heavy.
Funnily enough I had the same conversation with our driver trainer this morning as I noticed a pronounced drop in my fuel figures over the last three weeks. The first week I put down to it being quite windy and it seeming that no matter which way I was heading it seemed to be into a head wind!
I’d developed a layman theory that maybe Euro 6 engines when swallowing very cold air maybe overfuel for some reason. Anyhoo the trainer popped up some graphs on his computer which showed me that the whole fleet (a mix of DAF, Merc, MAN & Scanny) had dropped by around 12% over the last three weeks. He mentioned some stuff about dense air etc but I’d lost interest as the new office girl with massive norks had walked in by then.
the maoster:
Funnily enough I had the same conversation with our driver trainer this morning as I noticed a pronounced drop in my fuel figures over the last three weeks. The first week I put down to it being quite windy and it seeming that no matter which way I was heading it seemed to be into a head wind!I’d developed a layman theory that maybe Euro 6 engines when swallowing very cold air maybe overfuel for some reason. Anyhoo the trainer popped up some graphs on his computer which showed me that the whole fleet (a mix of DAF, Merc, MAN & Scanny) had dropped by around 12% over the last three weeks. He mentioned some stuff about dense air etc but I’d lost interest as the new office girl with massive norks had walked in by then.
Norks 
Defo not a Euro 6 thing. I think the one I’ve had for the last few weeks is still Euro 4 or at a push a very early Euro 5 (07 plate).
Diddycoys are nicking it. 
Harry Monk:
Diddycoys are nicking it.
That’s what they thought Harry, but that was put to bed when it was pointed out that the figures come from fuel going through the injectors.
toonsy:
Just this week there’s been a very noticeable increase in fuel consumed. I’m not talking like full tanks disappearing more a case of I’m using about 1/4 a day but previously it was less for roughly the same miles.Any ideas for what to look at? Could it be because it’s cold? Weight carried has been similar day by day and all gauges including turbo are reading fine. It’s also half way through it’s service cycle so it’s not way out of dock or anything.
Winter diesel has more anti gelling agents added which means a lower value burn, in turn this means using more fuel for the same power /torque output. Cold weather means longer engine warm up which results in less fuel efficiency. Combined this is the reason youre using more fuel…
If vehicles were fitted with a proper temperature gauge which reads in degrees (like they used to be) rather than these vague ‘indicators’ that are fashionably fitted, one could notice immediately that the engine is running too cold, hence it is inefficient and using more fuel. Back in the '70s quite a few operators specified Kysor thermostatically controlled radiator shutters. CM published an article about Smith of Maddiston fitting them to ■■■■■■■ powered Guy units to improve fuel consumption. Go back far enough in time before antifreeze was in common use and you will hear stories of the radiator bottom tank freezing while the vehicle was in use.
Now that vehicles are so powerful anyway it is not so apparent that the thing pulls better uphill when it is really cold. Drive something without a turbocharger and it is noticeable.
edit: add link
If its been this week it matches the cold air mass the UK has been steeped in.
Cold air hammers mpg, especially on diesels.
1/ cold air is denser, the engine MAF/ECU determines mass airflow and regulates more fuel to achieve correct mixture.
2/ thermal effiecency reasons. Low environmental temp, low air intake temp and higher fuel flows lead to longer warm up times. Diesels are less efficient when operating below working temp.
3/ higher loads on engine through accessories. Heating elements, blowers etc.
cav551:
If vehicles were fitted with a proper temperature gauge which reads in degrees (like they used to be) rather than these vague ‘indicators’ that are fashionably fitted, one could notice immediately that the engine is running too cold, hence it is inefficient and using more fuel. Back in the '70s quite a few operators specified Kysor thermostatically controlled radiator shutters. CM published an article about Smith of Maddiston fitting them to ■■■■■■■ powered Guy units to improve fuel consumption. Go back far enough in time before antifreeze was in common use and you will hear stories of the radiator bottom tank freezing while the vehicle was in use.Now that vehicles are so powerful anyway it is not so apparent that the thing pulls better uphill when it is really cold. Drive something without a turbocharger and it is noticeable.
edit: add link
There I was in my car on the southside of Brisbane, in a line of stationary traffic, window open minding me own business when a Mack rolled up beside me. Just as he stopped, his radiator shutter slammed shut… I nearly went through the roof.
toonsy:
Grumpy Dad:
toonsy:
Just this week there’s been a very noticeable increase in fuel consumed. I’m not talking like full tanks disappearing more a case of I’m using about 1/4 a day but previously it was less for roughly the same miles.Any ideas for what to look at? Could it be because it’s cold? Weight carried has been similar day by day and all gauges including turbo are reading fine. It’s also half way through it’s service cycle so it’s not way out of dock or anything.
What you driving, what load & weights etc
Could be something simple like tyre pressures the cold weather does change them a company I worked for had their fleet running with nitrogen filled tyres.
Could be the pre filter in the air intake that’s clogged.Tyre pressures is unlikely because we have to drive over a pressure sensing plate which pings up warnings if the PSI is outside a certain tolerance. Running Scania btw. Never normally near the weight limits (It’s normally foam insulation boards) as the loads have been bulky rather than heavy.
Well that’s a new one on me!
Just a thought, slower traffic due to the weather would mean the gearbox keeping itself in lower gears and effecting fuel economy.
cav551:
If vehicles were fitted with a proper temperature gauge which reads in degrees (like they used to be) rather than these vague ‘indicators’ that are fashionably fitted, one could notice immediately that the engine is running too cold, hence it is inefficient and using more fuel. Back in the '70s quite a few operators specified Kysor thermostatically controlled radiator shutters. CM published an article about Smith of Maddiston fitting them to ■■■■■■■ powered Guy units to improve fuel consumption. Go back far enough in time before antifreeze was in common use and you will hear stories of the radiator bottom tank freezing while the vehicle was in use.Now that vehicles are so powerful anyway it is not so apparent that the thing pulls better uphill when it is really cold. Drive something without a turbocharger and it is noticeable.
edit: add link
My Ford Transit 2.5 Di (non turbo, thank you) is definitely taking (even) more time going up hills since the temperatures have dropped. Also takes longer to start when cold. Time for an oil change me thinks.
TiredAndEmotional:
toonsy:
Grumpy Dad:
toonsy:
Just this week there’s been a very noticeable increase in fuel consumed. I’m not talking like full tanks disappearing more a case of I’m using about 1/4 a day but previously it was less for roughly the same miles.Any ideas for what to look at? Could it be because it’s cold? Weight carried has been similar day by day and all gauges including turbo are reading fine. It’s also half way through it’s service cycle so it’s not way out of dock or anything.
What you driving, what load & weights etc
Could be something simple like tyre pressures the cold weather does change them a company I worked for had their fleet running with nitrogen filled tyres.
Could be the pre filter in the air intake that’s clogged.Tyre pressures is unlikely because we have to drive over a pressure sensing plate which pings up warnings if the PSI is outside a certain tolerance. Running Scania btw. Never normally near the weight limits (It’s normally foam insulation boards) as the loads have been bulky rather than heavy.
Well that’s a new one on me!
Walkers (the crisp peddler) have one when you pull up at the exit gate. Always wondered how they work.
There might be one particular driver at your place who is doing exceptionally well lately
If a drop from about 10 15 degrees to about zero causes an increase of fuel use of ten or more percent, shouldn’t there also be an decrease in fuel use from air temperature rising from 10 or 15 up to 25 or more in the summer? Does the fleet run 10% or better fuel in the summer?
Haven’t there been high winds recently? Remember resistance from air is proportional to the square of the speed. If you’re driving at 100km/hr in still air is a constant drag. If in a wind of 100km/hr for half the trip it’s zero drag for the other half it’s twice the relative air speed so FOUR times the drag. Overall you’d expect double fuel consumption! (Obviously a simplified version, but you’ll see the effect).
Those with companies who keep good fuel records of large fleets should look at (among other things) the normal spread of variability in the figures as well as looking for any treads and it may be good to look at weather, but look at ALL possible factors causing fuel use differences, including temp, wind speed, etc. Fuel figures for a fleet should be a useful tool but only if someone has some basic skills in understanding and interpreting them.
As another aside nitrogen filled tyres? As a small advantage in a racing team, that’s one thing. But when the air around us is mostly nitrogen anyway how much difference does it make in the real everyday world I wonder? Has someone read about F1 teams and thought “if it works for them etc” or have they done any comparative testing and cost analysis?
EDIT. When I said double fuel use I meant double fuel use -to overcome drag- .
This would translate to less than double for real world on road use. And I haven’t had my breakfast or morning coffee yet, so excuse me please.
Franglais:
.
As another aside nitrogen filled tyres? As a small advantage in a racing team, that’s one thing. But when the air around us is mostly nitrogen anyway how much difference does it make in the real everyday world I wonder? Has someone read about F1 teams and thought “if it works for them etc” or have they done any comparative testing and cost analysis?
.
I think the main reason for using 100% nitrogen is that the tyres hold their pressure for longer as nitrogen leaks (migrates I think they call it) out through the rubber more slowly than oxygen does because a nitrogen molecule is bigger or something. It is also more stable in terms of not expanding / contracting so much with temperature so causing less of a pressure change. Presumably that’s the main reason racing people use it as I cannot see there is much time for “migration” in a F1 race
Freight Dog:
If its been this week it matches the cold air mass the UK has been steeped in.Cold air hammers mpg, especially on diesels.
1/ cold air is denser, the engine MAF/ECU determines mass airflow and regulates more fuel to achieve correct mixture.
2/ thermal effiecency reasons. Low environmental temp, low air intake temp and higher fuel flows lead to longer warm up times. Diesels are less efficient when operating below working temp.
3/ higher loads on engine through accessories. Heating elements, blowers etc.
Point3- looks good to me.
Point1- with more air (weight) per stroke and a proportionally equal amount more fuel I can see that an engine will perform better with cold air (thats why we have intercoolers on turbos). I can’t see why it would be greatly less efficient?
Edit
Point2- engines may take longer to reach temp but they still get there ok.