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

[Arragonis]

Hi,

If I put the SG2 into Hybrid mode so it deals with Engine off when still running are there any other issues on my TDI ? Will it still turn off when the ignition key is pulled as it does now ?

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

Ta.

A.

[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.

[Arragonis]

Yep, that has been covered but I have it reasonably close tank to tank.

I wondered before I mess up the calibration about it continuing to monitor FE if the engine is OFF when coasting.

Will this work, however inaccurate ?

[Vwbeamer]

My scangauge is usually within .5 of a gallon on fillups...seems pretty accurate to me.

Are your sure you have diesel selected as fuel on yours?

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.

[dcb]

they might have improved it some by taking in tps or something. 95% would be better than nothing.

Can you do an experiment? while cruising at say 50 in top gear and watching instant mpg, see if opening or closing the throttle have an impact on mpg or if it is tied to engine rpm.

[Arragonis]

Originally Posted by dcb

they might have improved it some by taking in tps or something. 95% would be better than nothing.

Can you do an experiment? while cruising at say 50 in top gear and watching instant mpg, see if opening or closing the throttle have an impact on mpg or if it is tied to engine rpm.

Throttle down mpg on the SG2 can go down to < 20 mpg, sometimes under 10. Lift off and it can go up to 9999.

I have even seen negative MPG on the overrun. Piwoslav thought I was ace

[dcb]

Originally Posted by Arragonis

Throttle down mpg on the SG2 can go down to < 20 mpg, sometimes under 10. Lift off and it can go up to 9999.

Just to clarify, this is for a given gear at about the same speed? Sounds like they are making a swag at the fuel delivery map.

Thanks for the perception update

[COcyclist]

The ScanGuage II is pretty accurate on my TDI although if I mash the pedal to the floor, it wil go to 9999 for a few seconds and I know that's not right! 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. Depending on my coasting speed (engine on, in neutral) my ScanGuage reads 300-450 miles per gallon Or more! and that's not too bad. I was worried about shutting off the oil supply to a hot turbo, wear and tear from bump starting so often, and on my car, disabled airbags while the key is off. I am sure it can be done safely under the right conditions. I will be following your progress.

[Arragonis]

Originally Posted by COcyclist

The ScanGuage II is pretty accurate on my TDI although if I mash the pedal to the floor, it wil go to 9999 for a few seconds and I know that's not right! 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. Depending on my coasting speed (engine on, in neutral) my ScanGuage reads 300-450 miles per gallon Or more! and that's not too bad. I was worried about shutting off the oil supply to a hot turbo, wear and tear from bump starting so often, and on my car, disabled airbags while the key is off. I am sure it can be done safely under the right conditions. I will be following your progress.

Originally it was just an idea but I'm taking it more seriously. I've been watching the GPH at idle which registers 0.16 after calibration. How does that compare with yours ?

I have done a few days of experimenting with Off coasting for a small section of my daily grind and apart from having cold toes the other difference was that the average mpg at the end of the queue was 40 instead of a more usual 30-33, and at the end of the journey overall the average was nearer the magic 60 target instead of a more normal 45-50.

This is at the start so everything is cold including the turbo which hasn't been mashed yet. I let it idle for a bit to get fresh oil in there before shutting off anyway.

So I wondering about using it a little more but it takes so long to go through a tank at the moment I was hoping the SG2 would give me some more feedback.

The above figures are from the on-board computer which seems to continue to calculate the average when moving and engine off but the SG2 goes to sleep and 'freezes' where it was. I use the SG2 to have an average and instant MPG figure as well as temps - e.g. my on board temp gauge only starts at 50 Deg C.

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

[COcyclist]

Originally Posted by Arragonis

Originally it was just an idea but I'm taking it more seriously. I've been watching the GPH at idle which registers 0.16 after calibration. How does that compare with yours ?

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.