Fuel economy indicated v real in TDCi

[Aus911]

Hi all, I have a 2010 Mondeo Zetec TDCi 120Kw with Powershift transmission.

I have noticed normal use the average l/100km indicates 5.2l/100km.
I always reset the trip computer to monitor this and noticed that the indicated l/100km is usually around 5.2 but when I do calculations of distance/fuel used it equates to approx 6.7 l/100km (approx 67l for 1000km).
Has anyone else experienced this. It looks like the dash is set to sell the car??
Anyone know how to calibrate this to indicate more accuralty?

What "real" fuel economy are people getting in their TDCi Mondeos?

[sailaway]

Nope! Same car but average is 6.7 L/100km

Have never seen any figures in the fives.

Maybe you are resetting it too frequently. Just a thought.

[Aus911]

I reset when I fill the car. I drive 100km each way to work, all freeway driving, I average 90+ km/hour for the weeks drive. Yep 1000+ km a week to work!!
Is your 6.7 L/100km on the readout, or calculated by km driven and litres used. My car has a large error between the two.

[whitelion65]

No. On the Mondeo, mine is spot on.
My Berlina is about 10% optimistic, something I can adjust through dash settings.

[Aus911]

WhiteLion65, thanks for the reply, for curiosity what economy are you getting?

[whitelion65]

Low sevens. Too many short trips on hilly terrain.
Get a bit better when I drive, as opposed the SWMBO!

[Aus911]

That is funny, at my place SWMBO also has a lead foot!!

[whitelion65]

I travel faster, but use less fuel. Go figure!!

[rondeo]

I get 6.4l/100km from my tdci wagon, mainly hilly country. That's about 1093 km for a 70l tank, although I seem to remember getting more like 1100 to 1200 km. The speedo indication is always 3-5 km/h higher than GPS suggests. Is this to safeguard against legal liability? Revolutions are foolproof, just count them. Time and flow are more flexible.

According to the Ford brochure the hatch gets 5.9 and the wagon 6.2 l/100km.

Ford approved oils are designated 'fuel efficient', I gather the viscosity at higher temperatures is lower, therefore less resistance to shear. Oil manufacturers claim 3 percent less fuel use.

[Aus911]

Hi Rondeo,
Thanks for the reply, is that economy on the instrument read out or your calculations?
On my car there is quite a difference, I am trying to work out if it is just my car, or all TDCi Mondeos?

[rondeo]

I have once or twice confirmed the dash readiing is correct. It's so consistent now I don't bother. Sometimes I just check when filling up that the kms remaining indication tallies approximately with the remaining fuel ie 70 - the number of litres put in.

I don't know how the fuel flow is measured on the car, or whether a calibration procedure exists in the Ford system. I haven't heard of it being a common issue.

[rondeo]

I'd guess that the instantaneous fuel consumption is calculated by a module based on fuel pressure and temperature and injector open time for example. Errors in the sensing
of these things might cause errors in the displayed fuel consumption.

DPF regeneration uses fuel to heat the DPF, there is a separate injecting device between the CAT and the DPF. Pure speculation but what if that were leaking?
If that fuel is also monitored, then also possibility of error.

Sorry no real hands on answer from me!

[Binny]

It can vary so much depending on conditions and the driver. I tend to be very smooth and anticipate whats going on ahead. In traffic I will watch the car in front of me accelerate, brake, accelerate, brake while over the same distance I haven't used either. Timing is everything.
Now my wife doesn't ever drive it I have averaged 5.8 over the last 15,000 km (I see a pattern here!). When I have calculated it manually I get about 5.9 - 6.0 so very close.

Do you really get 67 litres into it? Geez it must be empty when you fill it. I don't fill mine often I tend to put 40 bucks in which gets me my 500km week easy. When I have filled it right up I have never done under 1100km on that tank.

One thing to note if if yours has a chip in it the figures will be out by quite a lot. The chips fool the ECU into thinking the fuel pressure is lower so it increases it to compensate. This gives you better performance but their economy claims are BS for this reason.

[Aus911]

Hi Binny,

Yep, on Friday when I filled I managed to fit 70L into the tank, the computer said 7 km to empty, so that seems accurate.
Also it is a stock standard car...I think they are a great car so I don't see any reason in changing it.

Rondeo,
I don't think with my usage the car would do a DPF regen too often, once I did notice slightly higher consumption...but a leaking DFP injector could account for it... I guess I should check it out.

It looks like the indicated economy v real economy is just my car...oh well, I will live with it....at least I am aware of the error.

Thanks all for your replies!!!

[whitelion65]

Aus911,
don't run the fuel down that low. Big trouble if you run the system dry!!

[Aus911]

Hi Whitelion65,

Your right, I usually refill at around 100km to go...but daughter drove the car and put my routine out..I should have stopped earlier.

Good advice and thanks for the feedback!!

[cobrin]

I reckon 5's can be had but only if specifics were met. Those being 80kph flat roads probably done in one drive hwy type stuff. So not much use in day to day grind.

As whitelion has mentioned it's not a good idea to run that low or empty. I doubt there'll be a failure (on a rare occasion it may happen on) but you do open yourself to the risk of one happening. Diesel also serves in part a lubricant and coolant. Though the lubricating properties have reduced with low sulfur diesel.

I manage very often an average 6.8L/100km worst seen being 7.2. It's only slightly better than the last vehicle ('98 Corolla 1.8L man/sed) but it has sooooo! much more to offer a family of 5 (kids 4/8/10). The display is an ok indication but misleading compared to fuel use and K's driven.

I couldn't help my curiosity and am trying out Liqui Moly Diesel Clean and Boost, 1L will take an age to use going by ratios needed.