Fuel consumption same on long runs
Discussion
I've got a 2011 Mk3 Focus 1.6 VVTI, which consistently does 32-32.5 mpg around town. Recently we went down to Cornwall and then on to Devon for the week before returning home. During the trip the car didn't exceed 32.5 mpg at all. We filled it up before going to Newquay, it used an entire tank getting down there. Filled it up again to go to Devon, then another £40 before heading home.
Whilst its done over 100k now, I have it serviced annually and it runs well and starts every time. It did however really struggle getting up hills on holiday and required 2nd (and sometimes 1st gear) to pull. Its always been a totally uninteresting drive and the engine has never being able to pull you out of bed on a good day, but driving this thing has become more of an expensive chore to drive now.
I'm wondering if it could be a faulty oxygen sensor which isn't reporting a fault on the dash or bad fuel? I've had to clean the throttle body in the past, but apart from that its oil gets changed ever 5000-7000 Miles. Any idea's people?
Since returning home I've refilled it with BP fuel and its returning 32.8mpg around town now.
Whilst its done over 100k now, I have it serviced annually and it runs well and starts every time. It did however really struggle getting up hills on holiday and required 2nd (and sometimes 1st gear) to pull. Its always been a totally uninteresting drive and the engine has never being able to pull you out of bed on a good day, but driving this thing has become more of an expensive chore to drive now.
I'm wondering if it could be a faulty oxygen sensor which isn't reporting a fault on the dash or bad fuel? I've had to clean the throttle body in the past, but apart from that its oil gets changed ever 5000-7000 Miles. Any idea's people?
Since returning home I've refilled it with BP fuel and its returning 32.8mpg around town now.
How are you getting the mpg numbers
Trip computer display - reset at every tank fill and see what it says before next fill?
Brim fill and then miles travelled divided by fuel used to re-fill to get mpg?
Trip comps aren’t very accurate as a general rule (2-3 mpg either way)
If the trip comp has never been reset then even a long trip isn’t going to change the overall mpg by much
Trip computer display - reset at every tank fill and see what it says before next fill?
Brim fill and then miles travelled divided by fuel used to re-fill to get mpg?
Trip comps aren’t very accurate as a general rule (2-3 mpg either way)
If the trip comp has never been reset then even a long trip isn’t going to change the overall mpg by much
Yeah, you should measure at the pump using option 2 as above.
But, and guessing a little, you had a fully laden car that you say struggled to get up hills, on a trip that didn't involve much motorway. You probably had air conditioning on and if so it probably had to work. It's a fairly small naturally aspirated mid-2000s petrol engine of the sort that typically gets 30mpg no matter what you do.
If anything it's your around town figures that seem high to me. In city traffic I expect high 20s from this sort of car.
But, and guessing a little, you had a fully laden car that you say struggled to get up hills, on a trip that didn't involve much motorway. You probably had air conditioning on and if so it probably had to work. It's a fairly small naturally aspirated mid-2000s petrol engine of the sort that typically gets 30mpg no matter what you do.
If anything it's your around town figures that seem high to me. In city traffic I expect high 20s from this sort of car.
You can use a lot on a motorway run if you travel fast, faster you go the amount of air you shift increases exponetially as does the amount of fuel needed to shift that air.
Tyres inflated to high speed/full load running? Any extra roof racks etc, it all adds up.
Used to surprise me just how much fuel the Citroen C2 VTS HDi could use, general running around would return 50mpg no trouble, but anything over 70mph would see that figure rapidly diminish a fast long run could bring it below 40mpg, it must have had terrible aerodynamics because a Citroen C5 with the same 1.6 110hp Diesel would give better fuel figures at motorway speeds.
Tyres inflated to high speed/full load running? Any extra roof racks etc, it all adds up.
Used to surprise me just how much fuel the Citroen C2 VTS HDi could use, general running around would return 50mpg no trouble, but anything over 70mph would see that figure rapidly diminish a fast long run could bring it below 40mpg, it must have had terrible aerodynamics because a Citroen C5 with the same 1.6 110hp Diesel would give better fuel figures at motorway speeds.
The reported MPG seems very low to me too. I used to get low to mid 40s from a mk2 2.0 Mondeo on longer runs. High 40s were possible when stuck in interminable 50mph motorway roadworks for large parts of the journey. That engine should be far more efficient than the 2.0. Having said that, Honest John's RealMPG suggests the TI-VCT isn't as efficient as I'd assumed: https://www.honestjohn.co.uk/realmpg/ford/focus-20...
I think it needs some work with a decent scan tool or a trip to a decent garage. You say it's been serviced annually - is that a proper service with spark plugs and air filters etc. when required, or just an oil and filter change?
If the servicing is definitely up to the mark, I'd make sure you haven't got any slightly binding brakes. At higher speeds, the expansion of the discs and pads could make the drag considerably worse.
If that didn't get me anywhere I'd get it on a decent scan tool. Forscan (forscan.org) is a very inexpensive way of interrogating a Ford. After checking any logged codes for pointers, I'd be looking at long term fuel trims and the O2 sensor readings (as you suggest) for starters. Then I'd get the cam timing checked - is the VCT part actually working, and if you've had the cam belt changed, did you, or the garage, follow the proper timing procedure. I discovered that my aforementioned Mondeo had been set up using Tippex and ran much better after I'd had it apart and done it according to the Ford procedures.
I think it needs some work with a decent scan tool or a trip to a decent garage. You say it's been serviced annually - is that a proper service with spark plugs and air filters etc. when required, or just an oil and filter change?
If the servicing is definitely up to the mark, I'd make sure you haven't got any slightly binding brakes. At higher speeds, the expansion of the discs and pads could make the drag considerably worse.
If that didn't get me anywhere I'd get it on a decent scan tool. Forscan (forscan.org) is a very inexpensive way of interrogating a Ford. After checking any logged codes for pointers, I'd be looking at long term fuel trims and the O2 sensor readings (as you suggest) for starters. Then I'd get the cam timing checked - is the VCT part actually working, and if you've had the cam belt changed, did you, or the garage, follow the proper timing procedure. I discovered that my aforementioned Mondeo had been set up using Tippex and ran much better after I'd had it apart and done it according to the Ford procedures.
Buggerlugz192 said:
It did however really struggle getting up hills on holiday and required 2nd (and sometimes 1st gear) to pull. Its always been a totally uninteresting drive and the engine has never being able to pull you out of bed on a good day,
That’s a key bit of info, sounds very much like a blocked / collapsed catalytic converter. There are many other things it can be also but that’s the first thing I’d check given those symptoms. Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff