'rafe' What Is It Really?

[jimimaseye]

I ran the onboard dashboard diagnostic test on my Focus (you know, the one with flashy lights, wizzy possessed dials and a lot of nonsense to the lamen). A few clicks in there is one value that is called 'RAFE'

Having tried googling I have come across many different postings from people offering their idea or interpretation of what it is varying from 'Rate of Actual Fuel Economy', 'Running Average Fuel Economy' and other hybrid versions of these words all trying to say the same thing. These have been suggestions that it is the average economy of the fuel, taken at over the last 50 miles, the last 500 miles or the last 500kilometres and can be listed in MPG, L/km or l/100km (depending on your country).

However, I just dont believe any of this. And Ill tell you why:

My RAFE reading is 42.6 L/100km

Now, if I were to believe from above that its the average fuel economy over the last 500 kilometres, then that would mean the last tank of fuel (53 litres) would have got me all of 78 miles! And of course, it hasnt. My average MPG is normally about 47mpg (but currently sat at 45) which is more like 6L/100km. And to add fuel to my argument, I then went off and did a trip of about 12 miles and checking it again it still read 42.6 despite my high gear trip slightly increasing my MPG up a couple or three points. Ive also seen another post on this forum from someone who listed theirs at 43,5 L/100km - a figure roughly in the same bracket as mine. (Being in L/100km doesnt surprise me as its the standard thing in Europe to write fuel economies in such a 'volume-per-distance' way instead of the logical 'distance-per-volume' style. Yeah, go figure! Anyway, its only us Brits that then get it converted to ye-olde money for our viewing.)

SO....... all the theories above from all the other posters or unfounded as far as I can see. So what is 'RAFE'?

(Im happy to be proven wrong if it means getting the PROVEN demonstrated correct answer)

[FOCA]

Experts only have opinions - even in the scientific world, there are different opinions/ theories - it would have had an original intended meaning though

[artscot79]

On mine it shows the average mpg

[jimimaseye]

Experts only have opinions - even in the scientific world, there are different opinions/ theories - it would have had an original intended meaning though

err...... Riiiiiight......

On mine it shows the average mpg

Does it show in MPG or ? Is it the same one that appears on your regular dash (Average MPG)? What car are talking?

[artscot79]

Mk2 1.6 ti vct shows total average mpg

[jimimaseye]

I wonder what the difference is then and why yours is as such.

[simcor]

The best guesstimation is as follows.

It probably stands for running average fuel economy suggested to be done over the last 500 miles, the OBC then uses this data along with tank level information to work out the distance to empty based on the historical reading.

I would say that is the most likely scenario based on the info I can fins on the web.

My ZTT has the same kind of menu but on that you can change a correction factor after working out by brim to brim fill ups the actually average economy, using that data you can then work out a correction value so the OBC MPG reading is much more accurate, there does not seem to be a similar function on the Focus though.

I find my MPG readout to be about 7MPG out reading higher than my actual fuel consumption.

[jimimaseye]

I hear what youre saying, but that is an idea that simply doesnt fit with my figures. MY fugre is 42.6 litres/100km which makes my last tank of fuel last 75 miles (which isnt true). In august I did a 2200 mile round trip on holiday and using fillup-to-fillup checking my MPG OBC said 55.1mpg but my actual calculation worked out as 54.41mpg - so not too far out.....and certainly not the 10.6MPG that the RAFE figure is suggesting. So I am still open for a proven explanation as to how these figures of 46.2 or 43.5 L/100km come about.

[simcor]

I'm not sure as to why your figures are as they are. I am fairly sure the RAFE figure on mine is around the mid 40's to the gallon which on average I am somewhere between 42-45MPG on average but that is mostly short journeys to work with a fair bit of stop start and cold engine runs.

[simcor]

Plus it still is the most logical answer. For the computer to show the average fuel economy it has to work out how many miles the car has travelled over a certain distance and how much fuel it has consumed to do that. Then armed with that info and using the actual fuel level in gallons it can then work out how many miles are left in the tank based on how many gallons there are and based on the historical MPG figure.

[jimimaseye]

Hi Simon

I have no qualms or objections to the way it calculates 'miles remaining' - it needs a current rate of fuel and a current fuel level. No argument.

My doubt is the explanation of the RAFE figure as in the examples given they do not come close to equating to being responsible for the 'miles remaining'; my OBC DISPLAY of 'avg MPG' does, but not my RAFE reading. My RAFE reading and avg MPG are way way different. It's also interesting to see how my UK car has this figure as L/100km and yet yours (assuming also a UK car) shows it in MPG.

[simcor]

I can't remember if I changed the figure from L/100Km to MPG or not tbh, I did ask to find out how to change the HEC to show in MPG and also temperature in ºC as I was only able to show MPG with ºF which was a pain for me. From meory going into settings reset menu you can choose metric or imperial for those figures, one give you L/100KM and ºC the other option gives you MPG and ºF. to then change the ºF to ºC you have to go on the ambient temp screen and press and hold the reset button and it will change to ºC, whether any of that affects the RAFE figure between L/100Km andMPG I have no idea.

Mine is currently showing 46 MPG on the OBD and the RAFE figure in the hidden menu is also 46MPG.

The only logical reason I can think of for yours being so different is something is amiss from a sensor or such like that the figure is totally incorrect, have you tried disconnecting the battery for half and hour or so and then seeing what the figure defaults to in the RAFE readout? Cars with a lot of electric wizardry often go screwy and need a good hard reset from time to time.

That is the best answer I can come up with as most peoples results seem to tally mine it seems, your car must be a special one lol

[simcor]

I have actually tried setting mine back to how it was when I got it and it still shows the RAFE figure in MPG.

If the battery reset does not change anything I would suggest getting it onto a diagnostics and seeing if it is throwing up any error codes might help figure out a explanation possibly but also might not.

[simcor]

Just another thought do you reset all your trip meters when you fill up each time? or do you leave it all as is?

I always reset mileage, MPG and speed readings each time I fill up, just read something saying resetting the historical data might set if back to a default value.

[jimimaseye]

Special: yeah thats likely. In the 'he likes like a normal boy but obviously he's different from the others and needs a little extra tutoring' kind of special. (or SODS LAW as they call it). Although clearly I am not the only one with such a reading so I am not unique.

I dont want to do any battery disconnecting; too much hassle with radio codes and setting resetting.

I checked for error codes in the diag menu and all is clear.

Overall, there isnt a problem as such: my 'miles to empty' is calculated correctly (tallying with my fuel gauge and my displayed 'avg MPG'), its just a question of the meaning of this hidden value (and it not tallying with the suggestions I have read from google). This is why I posted the question on the hope that a definitive proven explanation was available. (I sometimes reset AVG and TRIPS etc and sometimes I dont. Depends whether I am filling up or not - usually reset on a FILL UP)

(After all, if I hadnt have read about the hidden TEST menu on this forum, I wouldnt have gone into it and seen it and consequently it wouldnt bugging me now. DARN THOSE USEFUL INFORMATION FORUMS!!! :P )

p.s my OBC is in MPG and Celcius. I only have on my OBC Setup 'DISPLAY - MEASURE UNITS - and choice of Metric or Imperial (which I am at Imperial). This has given me MPG but I still have CELCIUS and there is no setting anywhere to change the temperature measurement.

[simcor]

To change the temp from ºC to ºF simply go to the screen showing the ambient temp then press and hold the reset button it will then change to the opposite of what is is currently on and pressing and holding will set it back again.

It does indeed seem odd that the miles remaining and average fuel economy is showing correct but the RAFE figure is showing incorrect, it certainly is an odd one, if that figure was wrong you would expect the remaining miles and MPG to also be wrong.

It really is a head scratcher.

[jimimaseye]

It does indeed seem odd that the miles remaining and average fuel economy is showing correct but the RAFE figure is showing incorrect, it certainly is an odd one, if that figure was wrong you would expect the remaining miles and MPG to also be wrong.

...unless the explanation of RAFE is not what people think. (A thousand OPINIONS saying the same thing doesnt make a fact, it just makes 1000 opinions with a fact still potentially missing).

Hence the question.

[simcor]

...unless the explanation of RAFE is not what people think. (A thousand OPINIONS saying the same thing doesnt make a fact, it just makes 1000 opinions with a fact still potentially missing).

Hence the question.

Indeed I agree with that but with mine showing the same figure as my OBC then I have to accept it is the most likely answer lol for me at least.

[simcor]

Oh and I would still get it on a diagnostics kit myself as the hidden menu only shows DTC codes related to the HEC as I understand it, mine does not show DTC codes that my IDS picks up. I think people often think it will show full DTC codes from the PCM.

[jimimaseye]

And I too would think the same as you in the same situation.

But then when other examples appear where it simply doesnt match, I then have to begin to wonder.

(In fact a few questions have come out of this:

1, what does RAFE REALLY mean?

2, why are 2 UK cars showing the unit differently (L/100km or MPG)

3, why did I look into it in the first place?! Its not that I can do anything about it)

p.s I did find it useful to know the ACTUAL SPEED reading was available in the TEST display menu which confirms my idea of 'lack of calibration' of the speedo, and that my tomtom gives me a better reading of my travel speed than the speedo does. Useful to know when going through speed cameras on the limit.

[simcor]

And I too would think the same as you in the same situation.

But then when other examples appear where it simply doesnt match, I then have to begin to wonder.

(In fact a few questions have come out of this:

1, what does RAFE REALLY mean?

2, why are 2 UK cars showing the unit differently (L/100km or MPG)

3, why did I look into it in the first place?! Its not that I can do anything about it)

p.s I did find it useful to know the ACTUAL SPEED reading was available in the TEST display menu which confirms my idea of 'lack of calibration' of the speedo, and that my tomtom gives me a better reading of my travel speed than the speedo does. Useful to know when going through speed cameras on the limit.

1. God knows for sure

2. Why not? lol

3. Cause your a sucker for punishment like most of us lol

Regarding speed I am never quite sure on that tbh most speedos will be out py a certain amount and people do say GPS is more accurate, although driving trucks for a living the tachograph has to be calibrated every 6 months to be spot on so the speed as read by the tacho should be as accurate as possible, this shows 90kph or 56.25mph but my GPS often shows 55 or 56 and sometimes 57mph. I would liek to think a calibrated tacho and speedo should be the most accurate as with GPS there is going to be a delay as the signal has to travel a long way.

Regarding average speed cameras I sit at 56mph through them all day every day and have never got a ticket. people who drive at 50mph and wont overtake and hog the middle of third lane really !Removed! me off, not to mention those that go even slower than 50mph.

In fact I hate people who slow to below the speed limit every time they come to a camera for gods sake!!

Rant over.

[jeebowhite]

AFAIK, the RAFE figures are the ones used to control power delivery etc. When you put your car into learning mode, this goes to zero. as you drive, it works out the average, along with fuel used etc to identify how you drive the car, this would then be used as part of the power delivery on a day to day basis, so if the car knows you favour fuel economy over speed, it will deliver less fuel to get you to where you are and pulls back on the power. Then, if you want to adjust and drive heavy footed all the time, it takes a long time for it to adjust.

This is why if your MPG is poor, you reset the battery and then drive as you want to and it improves the MPG.

[simcor]

Well I have just tried resetting my MPG meter and it also reset .y RAFE to 0.0 mpg and shows the exact same figure as the OBC MPG readout. So still unsure why yours is in L/100KM.

[jimimaseye]

AFAIK, the RAFE figures are the ones used to control power delivery etc...This is why if your MPG is poor, you reset the battery and then drive as you want to and it improves the MPG.

So, considering all this, why does my RAFE say (equivalent of) 6.7 MPG and how would this effect my fuel regulation in this scenario? (I am quite a slow/careful driver and think that I get the best economy out of my car within my control. 44-45mpg around town and 57mpg on 2000mile drive trip (without about town driving)

[jeebowhite]

clearly I was wrong on the basis Simon reset his, and it reset to zero, so my understanding of it just changed :P

As for the driveability - get your radio code out, disconnect the battery and leave it for 30 minutes, then go back and start driving how you will continue to do so.

This will give you a chance to get your car to how you drive it.

I got my mondeo 6 months ago, first 3 tanks of fuel averaged 400 miles, reset the car, drove it as I do, I now get between 650 and 700 per tank.