fuel consumption on a diesel engine

**pwb** · 09-21-2008, 10:02 AM

Hi, why dont company like myscantool and other tell that there software cant be used on a diesel engine to messure fuel consumption? The only comapany that have bees open on this is glmsoftware.com they said they dont support dieselengines since a diesel engine cant be messured with maf. The most (ALL?) of the software use MAF and that cant be used on a diesel engine, many says that ScanGauge II can be used on a diesel engien, but is that correct? If thats correct, is there someone that now how to calculate the MPG on OBD data from a dieselengine? I think there must be many many many peopel out there running software and dont now why i the h**** ther car use so much diesel when standing still.

/pwb

**p2psmurf** · 10-21-2008, 03:58 AM

The problem with measuring fuel consumption on a diesel engine, is that the engine management system does not use the MAF-sensor for calculating the amount of diesel injected. Also there's no relatively fixed ratio between air and injected fuel like on a petrol. In short, it can't be done.
Even on a lot of petrol engines you cannot calculate fuel consumption because they use a MAP-sensor in stead of a MAF-sensor.

Why don't those companies tell you this? Well, I can think of 2 reasons, you will have to choose for yourself
a) They know, but don't tell you, because all they are interested in is selling their hardware and/or software.
b) They have no idea how an engine and/or an engine management system, especially a diesel, works.

**Gilbo** · 05-19-2009, 07:32 AM

I read p2psmurf's reply with interest - and a personal growing confusion.

Here in Australia, there are several members of an internet community for Toyota 4WD owners that are operating ScanGaugeII trip computers that seem to be getting accurate figures for fuel consumption in diesel engines. This seems to be evidenced when they fill their tanks there is less than 2 litres difference (over about a 150L fill) than what the ScanGauge indicates. I assume the gauge accumulates the instantaneous fuel figures to work out how much fuel has been used. This also must be the same way to calculate the average fuel consumption between fills.

Seems to me that the ScanGaugeII does calculate fuel consumption for diesels. Does anyone else disagree - and can tell me how the gauge seems to do this?

What I really want is to use a OBD scanner that can feed my carPC (like the ElmScan) that can give me more visual information like graphs, data logging etc. I am particularly interested in fuel consumption since I am about to tow a large caravan (I think you call them mobile homes) across Australia for 3 months and this information will help select the best speed/gear for fuel consumption in various conditions.

Can anyone help advise me what to do - or is the ScanGaugeII the only one that seems to do this natively (I don't really want to do loads more programming just to get another system going)?

Thanks for any assistance

Gilbo

**chunkyks** · 05-19-2009, 01:18 PM

What I really want is to use a OBD scanner that can feed my carPC (like the ElmScan) that can give me more visual information like graphs, data logging etc. I am particularly interested in fuel consumption since I am about to tow a large caravan (I think you call them mobile homes) across Australia for 3 months and this information will help select the best speed/gear for fuel consumption in various conditions.

Heh. Heh heh.

OBD GPS Logger

It's been my personal project for a while, now. It probably doesn't do *exactly* what you have in mind, but it may be a good start.

Gary (-;

**pwb** · 05-22-2009, 02:06 AM

Originally Posted by Gilbo

I read p2psmurf's reply with interest - and a personal growing confusion.

Here in Australia, there are several members of an internet community for Toyota 4WD owners that are operating ScanGaugeII trip computers that seem to be getting accurate figures for fuel consumption in diesel engines. This seems to be evidenced when they fill their tanks there is less than 2 litres difference (over about a 150L fill) than what the ScanGauge indicates. I assume the gauge accumulates the instantaneous fuel figures to work out how much fuel has been used. This also must be the same way to calculate the average fuel consumption between fills.

Seems to me that the ScanGaugeII does calculate fuel consumption for diesels. Does anyone else disagree - and can tell me how the gauge seems to do this?

What I really want is to use a OBD scanner that can feed my carPC (like the ElmScan) that can give me more visual information like graphs, data logging etc. I am particularly interested in fuel consumption since I am about to tow a large caravan (I think you call them mobile homes) across Australia for 3 months and this information will help select the best speed/gear for fuel consumption in various conditions.

Can anyone help advise me what to do - or is the ScanGaugeII the only one that seems to do this natively (I don't really want to do loads more programming just to get another system going)?

Thanks for any assistance

Gilbo

Hi, i have tried many different software, free and comercials and none of them can messure fuel consumption on diesel engines. But there must be some information on what parameters ScanGaugeII use, anyone?

/PWB

**Rooster** · 05-22-2009, 02:01 PM

Maybe they use the change in 'fuel level' to estimate the amount of fuel used??

**chunkyks** · 05-22-2009, 02:12 PM

Hi, i have tried many different software, free and comercials and none of them can messure fuel consumption on diesel engines. But there must be some information on what parameters ScanGaugeII use, anyone?

Well, I'd start by hunting down a diesel and asking it what parameters it supports. Then post here a list, and see if any of the board gurus can create a formula given the available options

http://icculus.org/obdgpslogger/mini-supportedPIDs. Show something like this list, but for your diesel instead of my mini.

Gary (-;

**DigitalCorpus** · 05-22-2009, 02:15 PM

ScanGauge II will work on diesel engines. I have a VW TDI (Turbo Diesel Injected). I do not have a ScanGuage since I'm swapping out my instrument cluster for one with MFA functionality. From what I've read they are on the optimistic side when it come to measuring, but if you're consistent on your driving style, then it can be calibrated correctly.

http://forums.tdiclub.com/showthread.php?t=177645
http://forums.tdiclub.com/showthread...ht=ScanGaugeII

**rodweb** · 05-22-2009, 02:19 PM

Originally Posted by Gilbo

I read p2psmurf's reply with interest - and a personal growing confusion.

Here in Australia, there are several members of an internet community for Toyota 4WD owners that are operating ScanGaugeII trip computers that seem to be getting accurate figures for fuel consumption in diesel engines.

Seems to me that the ScanGaugeII does calculate fuel consumption for diesels. Does anyone else disagree - and can tell me how the gauge seems to do this?

Can anyone help advise me what to do - or is the ScanGaugeII the only one that seems to do this natively (I don't really want to do loads more programming just to get another system going)?

Thanks for any assistance

Gilbo

Gilbo, I am a diesel Toyota owner in Australia and am interested in this too. The problem is the standard OBDII data does not include anything which can be used to estimate diesel fuel consumption.

I have seen some discusions on a technical OBDII forum somewhere and it was indicated that in all probablity, Scanguage was pulling up some Toyota Specific Manufacturers PID codes that provides some insight into Diesel fuel consumption. From memory, it was likely that the fuel consumption was deduced from injector timing which could be used to measure fuel useage but my memory is a bit rusty. Me? I just log each tank full at the servo and caclulate consumption that way. See my build up for info.

One of these days, I will add OBDII to my car PC, but not for a while yet.

**pwb** · 05-22-2009, 03:11 PM

Originally Posted by rodweb

Gilbo, I am a diesel Toyota owner in Australia and am interested in this too. The problem is the standard OBDII data does not include anything which can be used to estimate diesel fuel consumption.

I have seen some discusions on a technical OBDII forum somewhere and it was indicated that in all probablity, Scanguage was pulling up some Toyota Specific Manufacturers PID codes that provides some insight into Diesel fuel consumption. From memory, it was likely that the fuel consumption was deduced from injector timing which could be used to measure fuel useage but my memory is a bit rusty. Me? I just log each tank full at the servo and caclulate consumption that way. See my build up for info.

One of these days, I will add OBDII to my car PC, but not for a while yet.

Injector timing? Many diesel engines is tuned up with a add on box, and then the timing is diffrent from what the "brain" tells the engine to use. So since a diesel engine is so totaly different from a gasoline engine ther is so many ways to do things wrong, so the best is to calculate MPG every time you fill it up.