Fuel consumption question

rrwfotr

Hi, I have a Fiat Punto 2002 model 1.2l 8v, and I have it serviced a couple of months ago i.e. oil change, spark plug change (ngk) air filter, oil filter change and also change anti freeze two weeks ago. The problem is since the cold weather the car appears to consuming more petrol then it used to not massively allot but a noticeable change for the same patterns of mileage on previous runs.

What I wish to know is that could the cold weather affect fuel consumption or could there be a defective part on the car?

Wig

A cold engine uses more fuel, short infrequent runs will harm your engine and cost more in fuel.

If we are talking here about medium journeys, <30 miles there will be a small overall increase but nothing too noticeable.

If long journeys there will be no noticeable difference, and if you are getting more fuel use you could have the coolant temp sensors checked/changed. Check your compressions in your cylinders (just a guess really it might be relevant).

tomstickland

Is it getting up to temp normally? Cold weather should allow an engine to be more efficient once up to temperature, but it chucks loads of extra fuel in during the warming up period. When coolant temperature sensors fail then the engine runs in cold mode all the time and uses loads of fuel. If the thermostat sticks open then the engine never warms up properly, but you'll see this because the temp gauage will stay low even after 15 minutes of running.

nelly_2

Its winter so we use the lights heater rear window heater, these all drain the battery and to compensate the alternator needs more power to fill it back up so the engine revs faster. You can actually here the engine speed change on our car when I switch the rear window on and off.

Wouldnt have thought it'd make that much difference though.

tomstickland

It won't make much difference since the power requirement is not going to top 100W or so. ie: 0.1KW and a small supermini engine will make around 60BHP which is around 45KW. . The engine doesn't rev faster when you need more electrical power. It usually slows slightly at idle when you put the extra demand on the alternator.

vansboy

Yes you WILL use more fuel in colder weather.

As mentioned, everything works that much harder & takes longer to reach optimum operating temperature.

Do check the temperature guage, is reaching it's 'normal' setting, during the journey - if it's not after say, 10 minutes & longer, then it would be worth checking the cooling system (garage job, really)

Does the heater work OK?? if not, then there may be a problem.

& don't try to 'push' the car to get goung while it's not warmed up - this uses more fuel & does no good to the engine. Far better with gentle acceleration, in the lower temeperatures & a cold engine.

VB

chrisw

My Peugeot 406 1.8 drops from around 33-34mpg in the summer to around 30-31 in the winter.
However, being climate-control, the air con is running most of the time in the summer but hardly at all in the cold.