C3 1.4 Petrol Mpg

[Guest stevemc]

my 52 plate c3 1.4 petrol is only doing 38mpg ,and thats on a run at around 65mph ,i have done oil and all filters ,plugs were changed 2thousand miles ago (ngk) ,when i took them out ceremic and the prong were a red colour ,i replaced them with bosch plugs ,but still the mpg has not changed ,

the engine management light is not on ,i have pluged a code reader on it ,there are no faults ,,i am now totaly lost ,i was expecting around 50 -55 mpg ,am i expecting to much

[argoose]

my 52 plate c3 1.4 petrol is only doing 38mpg ,and thats on a run at around 65mph ,i have done oil and all filters ,plugs were changed 2thousand miles ago (ngk) ,when i took them out ceremic and the prong were a red colour ,i replaced them with bosch plugs ,but still the mpg has not changed ,

the engine management light is not on ,i have pluged a code reader on it ,there are no faults ,,i am now totaly lost ,i was expecting around 50 -55 mpg ,am i expecting to much

 

 

Hi stevemc,

you didnt mention tyre pressures' are brakes in good order, lots of little things can alter mpg most not for the better. even down to dirty car causing more air drag, that's why F1 cars are highly polished, every little helps. best start with tyres, brakes and check exhaust, I got y reg xsara 1.4 petrol doing about 38mpg round town. Plus cars always drop a few mpg in cold weather. Hope this helps.

P.S. bung a drop of redex in tank. Might help, wont harm :)

[paul.h]

Our 2003 1.4 sx manual usually returns about 45 mpg in summer and about 40 mpg in winter. This December it has been colder than normal so was giving even less. MPG figures from the handbook are 34.4/56.5/45.6 mpg urban/extra urban/combined so you are unlikely to get over 50 mpg and at motorway speeds it is a bit underpowered so maybe not too efficient. Then when you come off the motorway into urban areas the economy drops off.

[Guest stevemc]

tyre pressures are right,brakes not binding (and its clean and polished ),i am a diesel fitter ,even had it over a pit at work ,cant work out why i only get 38 mpg on a run ,its at least 8 mpg less than i should be getting

[paul.h]

How many miles has it done, could there be a problem with the exhaust/catalyst blocked up ? Do not know what the symptoms for this would be though. How do you check the mpg, by miles against amount of fuel put in the tank or using the cars computer (if it has one since ours does not) ?

[Guest stevemc]

its done 76000miles ,its only a lx ,i work it out by filling it up to the top ,zero the mileometer,about 200- 300 miles later refill tank to the top

and work it out with calculater ,i.e 4.46 litres is 1 gallon and so on

[paul.h]

Only other things I can think of that may give poor fuel economy are a faulty thermostat so engine runs cold and a temperature sensor fault so causing a rich mixture. There are 2 temp sensors on the C3, both at the end of the cylinder head. The one on top goes to the gauge and the other at the side gives a high temperature alarm. I have assumed it is a manual gearbox.

 

How was the fuel economy on your previous car ?

[Guest stevemc]

the temp gauge gets 1 light on after approx 2 miles ,2 lights after 6 miles ,if the state was stuck open it would get colder on a run and warm up in traffic ,it just stays the same ,last car was a volvo v40 2l petrol on the same run was doing 37mpg ,but that was a big HEAVY VOLVO ,i think the c3 is going up for sale ,very soon

[paul.h]

The temp gauge lights are not that good an indication, they cover a wide temp band, if your code reader can give live data that is better. Our C3 usually has 3 lights up after 2 to 3 miles but that depends on how cold it is outside. Live data check on ours gave 2 lights at about 70°C and 3 lights at 81 to 96°C when the fan cuts in. The thermostat is supposed to open at 89°C so in our case should have 3 lights up. Other people have reported here that they only see 2 lights up.

 

It could be if you do a lot of miles and motorway driving the C3 is going to cost too much in fuel so not worth having and a diesel would be better. I tend not to use the C3 on motorways with it being such a small car. We have a 1.6 hdi C4 which gives 60 mpg on motorways (M62 Warrington to Hull) but over Xmas dropped to 52 but then was -9°C.

[Guest stevemc]

i am going to put a thermostate in it , but got to view a peugeot 307 hdi tomorrow

[argoose]

Another thing I found to improve fuel was to change from tesco to total/texeco, only a couple of pence more but car runs a lot happier and get better mpg to cover the pennies. Also heard good things about "cataclean". A good mate used it on a land rover disco, said it really sharpened the engine up