Fuel Economizer - Questions/Feedback/Requests

  • Last Post 19 April 2018
fuel sipper posted this 17 April 2018


I’m using some section numbers to help people reply to me :-

1.)I’ve been using OBDCarDoctor Pro IOS app V2.0.7.0 for over a week now (APR2018). Very useful, though I’ve some questions, feedback and requests. I’m trying to use it to help me improve my fuel economy, since my car has no mpg gauges. Specifically I’m trying to use the “fuel economizer” screen to help. I’ve already gone from 47 UK MPG to 62 MPG (driving at 62mph max) and would like to go further ideally using your app to help me.

2.) My car is a 2008 SEAT Ibiza 1.9TDI (99bhp turbo diesel, with no DPF as standard). The nearest engine in your database is 130hp though it appears this isn’t important for the fuel economy setting? Also the default engine volumetric efficiency of 0.8 I think has no impact? The engine has a MAF, engine load sensor, and intake manifold pressure sensor, which I believe are the key variables used for the economy calculations. Is my thinking correct? A detailed blog on how fuel economy is worked out for turbo diesels/petrol engines cars would be very useful and welcome. Is that possible in the future?

3A.) On the fuel economizer screen can I please request some improvements. Please allow the y axis of the graphs to be set by the user. User should be able to tap on the y axis and then set the min/max values to be used, or as a second preference allow dynamic scaling. Currently the maximum value is 30L/hr (consumption/flow rate) or 30L/100km. My “economy avg” is typically showing 6.75L/100km (42UK MPG) after a 30 min extra urban journey, so having the axis value being set to 30L/100km is not helpful and only flattens the graphs! I also can’t graph consumption, since the value varies typically from 0.03-0.25-1L/hr which is again very small compared to the fixed value of 30L/hr, so I cannot visually see it.

3B.) Can I please request the ability to display 4 items at the top of the screen instead of the current 3? I’m currently using “consumption” (fuel flow rate), economy avg (1min) & economy avg (journey). Can I also request the ability to graph 4 curves, rather than the current 2 curves? I’m graphing with the last 2 described economy variables which I find helpful.

3C.) I live in the U.K. and would like to use units of MPG (UK gallon), degC and KPa for units. I can’t currently mix the first 2 units. Also in the fuel economizer the units are Gallons/100mile which is a strange unit to work with! Can it please be changed to MPG (UK or USA gallon)?

4.) Why is my reported economy after a regular 30min, 22mile extra urban journey typically 6.75L/100km (42 UK MPG) yet I’ve tank averaged 62 UK MPG (4.56L/100km)? Is the engine power or volumetric efficiency actually being used after all and hence needs changing to get a more realistic fuel economy figure? How can I get the app to show more realistic fuel economy figures?

5.) At the bottom of the dashboard it shows the economizer average across all the journeys for the current day. It was showing an average of 19.75L/100km which is appalling poor and I don’t believe! However on the fuel economizer screen each of the 2 journeys that day had a journey average of around 6.75L/100km. How can this be correct? It’s not a one off result either. Is the dashboard summary actually reporting something completely different?

6.) Can you please do a blog that explains the file format of the text file that you can obtain from the fuel economizer screen. It doesn’t seem to make much sense currently. I’ve MAF, speed and maybe time in seconds, all without units!

I’m hoping you can answer my questions and especially implement my requests for improvements in the fuel economizer screen.

Thanks for your efforts,

Fuel Sipper

Order By: Standard | Newest | Votes
inCarDoc posted this 17 April 2018

Great thanks for the detailed review, questions and propositions!!!

Will try to answer/comment all points one by one below.

inCarDoc posted this 17 April 2018

1) The key idea of the Economizer widget is to give visually comparable presentation of instant (or short term economy) vs long term economy parameter. By default 10s average vs trip average. So at each moment you could see if you over or less average and correct your driving style (if possible in current conditions). Hope this helps

inCarDoc posted this 17 April 2018

2)  Model list have only "advisory" function, if your model does not listed in auto-complete you could just type in your model, set "custom" engine type and add requested fuel and engine displacement parameters. 

Fuel type always required for the Economy calcylation

Displacement and Volumetric efficiency is used only when car does not expose MAF parameter and economy is calculated via the MAP.

Some briefs about available on forum, for example here

I'll need to put together all details and publish in blog

inCarDoc posted this 17 April 2018

3a,b,c) Yes we will think about "smart" scaling (based on the history) and/or manual bounds settings. 

As for the extra on-screen parameters and graphs, frankly speaking I'm dislike idea overloading predefined Economy widget screen with more parameters... As alternative we plan to extend Combine commands functionality, so one be free to configure own multi parameters widgets... just might have time to make this.

The same for the "mixing" metrics and imperial units... just need to find a time

inCarDoc posted this 17 April 2018

4) If your car supports direct reading of MAF, the only influence on calculations have the fuel type settings (gas/diesel). In case of diesel it also requires engine Load parameter readings.

If all that Ok, we might need to get recorded traces and/or debug log to review our in-app calculations in your case.

fuel sipper posted this 17 April 2018

2.) Thanks, a blog about the technical calculation for economy would be very useful. My ECU has MAF, MAP & Engine Load sensors, according to your software. Which should mean that the volumetric efficiency is not required. I’ve chosen the related but more powerful 130bhp 1.9TDI engine version.

fuel sipper posted this 18 April 2018

3a.) min/max y-axis scale on the economizer screen is the most urgent priority. 3b.) I understand you about avoiding clutter on the economizer screen. It is quite tidy as is. Your alternative ideas sound interesting - I think you are talking about implementing them in the “dynamic parameters” section. If 3a is done then leaving the economizer screen alone is fine 3c.) Thanks.

fuel sipper posted this 18 April 2018

4.) Yes that info all seems to be present. How do I attach or send through an economizer log file for one journey? Do I use the app option “share with support” or “share with obd-car-doctor.com” to send you the economizer log file? (found in OBD records, then swipe left on an economizer or other log file). Also how can I send a picture?

fuel sipper posted this 18 April 2018

5.) 6.) Once I send you a log file and a picture that should hopefully help some.

inCarDoc posted this 18 April 2018

Yes, please use "share with support" to prepare and send economizer data. To send the picture, just capture a screenshot(s) when appropriate data onscreen and later attach to the letter with economizer data.


fuel sipper posted this 19 April 2018

For the posting record - info and app screenshots shared with support yesterday. Some email communication of progress today. Thanks.