TDI, EO(ff)C and SG2 for fun and profit

[euromodder]

Originally Posted by dcb

I don't have a good solution for diesels handy, have been thinking about it plenty though.

Using someone's advice here, I reduced the displacement to 3/4 of the actual displacement, i.e. 1.2L instead of 1.6L .
That got it fairly close.
Careful calibration did the rest - I'm currently at + 14.6% .

It's now accurate to within about 0.5L total fuel used on a tank (usually around 35-40L).

Tank average is accurate to to about 0.1 L/100km on a 5.0L/100km fuel consumption - it reads slightly high, but the distance reads 1% low

[Piwoslaw]

Originally Posted by Arragonis

I have resisted EO(ff)C so far but I may try some experiments...

Tempting, ain't it?

Originally Posted by COcyclist

Arragonis, are you considering E(off) coasting out of curiosity or in the name of science? Our diesels are so much more efficient at idle than a gasser (petrol) that I haven't felt that it was worth it.

What we're after is not using less fuel, but using even less.
And if you don't have to key off (kill switch?), then your PS, airbags, etc., should still work (mine do).

Originally Posted by Arragonis

If I go 'Hybrid' I understand the SG2 keeps going when the engine stops, but I suspect my calibration may be broken.

I tried using 'Hybrid' mode when playing with EO(ff)C, but in my case not only did the SGII turn off after a few seconds, but fuel consumption was total nonsense. I admit that was before I had my kill switch, so MAYBE it won't turn off if I don't turn the key, but the consumption will still be random. Also, even if SGII doesn't freeze up, it may or may not be getting all the info it needs: my factory installed FC computer doesn't register distance when EO(ff)C, but the odometer does. SGII - I haven't checked yet. I won't be driving before Saturday, and even then I'll be with the Wife, so I may not be able to do too many experiments with the engine off, but if I try something I'll let you know.

Maybe SGII needs a new mode, 'Diesel + Hybrid'?

[Arragonis]

Originally Posted by euromodder

Using someone's advice here, I reduced the displacement to 3/4 of the actual displacement, i.e. 1.2L instead of 1.6L .
That got it fairly close.
Careful calibration did the rest - I'm currently at + 14.6% .

It's now accurate to within about 0.5L total fuel used on a tank (usually around 35-40L).

Tank average is accurate to to about 0.1 L/100km on a 5.0L/100km fuel consumption - it reads slightly high, but the distance reads 1% low

This is pretty much where I am on calibration, but with more detail than I can muster at the moment.

[Arragonis]

Originally Posted by Piwoslaw

Tempting, ain't it?

What we're after is not using less fuel, but using even less.
And if you don't have to key off (kill switch?), then your PS, airbags, etc., should still work (mine do).

Some mild experimentation (yes I have been tempted ) seems to suggest that PAS and brake assist goes with the engine off even with the key right round although I think the Mk1 Fabia has leccy power steering.

A kill switch sounds interesting. Anyone made one for a TDI ? (I will search in a while, just lazy at the moment...)

Originally Posted by Piwoslaw

I tried using 'Hybrid' mode when playing with EO(ff)C, but in my case not only did the SGII turn off after a few seconds, but fuel consumption was total nonsense. I admit that was before I had my kill switch, so MAYBE it won't turn off if I don't turn the key, but the consumption will still be random. Also, even if SGII doesn't freeze up, it may or may not be getting all the info it needs: my factory installed FC computer doesn't register distance when EO(ff)C, but the odometer does. SGII - I haven't checked yet. I won't be driving before Saturday, and even then I'll be with the Wife, so I may not be able to do too many experiments with the engine off, but if I try something I'll let you know.

Maybe SGII needs a new mode, 'Diesel + Hybrid'?

Thanks, I maybe won't try the Hybrid mode given the calibration just now. The on-board comp still registers distance and therefore still calculates average MPG with the engine off.

Given these facts I'll probably keep the SG2 for tank to tank monitoring and use the on board for testing this idea out. The commute tomorrow will be the first go.

[Arragonis]

Double PS

Originally Posted by COcyclist

That sounds about right although it may go even lower when everything is fully warmed up and depends on how many electrical accessories I am using. Are you aware of the three extra glow-plugs in the coolant? They help these engines make some heat when it's cold outside but they are a pretty big current draw until they cycle off.

I missed this, how can I check I have these and if they are running ?

[COcyclist]

Forgive my lack of knowledge of the Fabia. Is this a VAG product? I assumed it is because you have the 1.9 TDI. On my car they are just to the right of the head. It is pretty obvious. A coolant hose connects to a fitting and three wires connect to that fitting.

You may be able to put your hand on that fitting on a cold startup at idle. It you feel heat, they are on. A diesel doesn't really warm up on it's own unless it is working hard. I was amazed this last weekend to start my car after skiing on a mountain pass, I started down the hill in gear using NO fuel (9999 mpg) and watched the coolant temps climb on the ScanGuage and make defrost heat as I decended the seven mile grade. Thanks extra coolant glow plugs.

[Arragonis]

Is is this part ?

[COcyclist]

There is a vacuum pump in the area shown in the photo too. It may be just under that vacuum pump if my memory serves me correctly. I will try to get a photo this evening. I have heard that some Canadian drivers change the settings in VAG-COM to keep those glow plugs on longer to get heat into the cabin more quickly.

[Arragonis]

OK Thanks. The photo is not my car, just another VRS. BTW the Fabia is really a VW Polo underneath, the VRS has the 130 ASZ TDI engine.

The new Fabia VRS has a petrol engine. The ads are fun though

original Fabia

http://www.youtube.com/watch?v=WhfEGKc7PLQ

VRS

http://www.youtube.com/watch?v=aHzYLJEZ9cw

Which is amusing as it has less torque than mine. I feel if I meet one my next tank may not be so good

[cfg83]

dcb -

Originally Posted by dcb

obdII solutions do not track fuel usage well on diesels. They assume a 14.1 ratio and watch the mass airflow.

Diesels (due to lack of throttle plate and compression ignition) do not operate at a relatively fixed mixture.

I don't have a good solution for diesels handy, have been thinking about it plenty though.

The SGII supports the following options, so I think the algorithm changes based on the fuel :

GAS, DIESELa, DIESELb, HYBRID and LPG

http://www.scangauge.com/support/pdfs/SGIIManual.pdf Manual

The upper 2 buttons can be used to step to the type of fuel used in the vehicle. Pressing HOME will exit the screen and use the fuel selected until the ScanGaugeII is disconnected. Pressing SAVE will place the selection into Flash memory and use the selection until it is changed. DIESELa and DIESELb do not refer to different types of diesel fuel. They only affect the way fuel consumption is computed and are selected based on the way the vehicle computer reports its sensor information. Most diesel vehicles use the DIESELa setting. To determine which your diesel vehicle uses, do the following:
With ENGINE SIZE set, DIESELa chosen for fuel, the engine warmed up to operating temperature and idling in neutral or park, select GAUGE and make one of the gauges show RPM and another show GPH. Note the GPH value. Next, use the throttle to raise the engine RPM to about 1500 RPM. If the GPH reading increased, you have a DIESELa vehicle. If the GPH dropped or stayed the same, you have a DIESELb vehicle and should change the Fuel Type to DIESELb. Hybrid vehicle must choose HYBRID or the ScanGaugeII will go to sleep when the engine automatically shuts off. Propane powered vehicles should use LPG.

PS - This is tangential to what the thread is really about, but I am posting it for the lurkers.

CarloSW2