How do you eco-drive a diesel ?

[syncro_user]

Experiencing something of a heatwave at the moment, up around 29C yesterday, with correspondingly great FE! I've noticed a significant gains driving the tdi hard during the pulse, possible to get over 100MPGimp/90MPGus, working the pulse to make the most of hills (pulsing up, coasting down). 5th gear gives better FE than 4th for the same P&G regime. Low revs, lots of torque, burn it hot, burn it hard. Just watch out for compressor surge, if you have some diagnostic software you can measure boost vs rpm to find how hard you can push it by comparing the measured curve with a compressor map.

Steady state driving best is up the the 80sMPGimp/70sMPGus so still good, not awesome but much more practical.

[COcyclist]

Originally Posted by mcbota

Also I am thinking if is worthy to change the wheels, in this moment I have 215/55/16 and I want to change with 195/65/15, but I am not sure how much I will gain!

In my opinion it would take a long time to recoup your investment unless you need to buy tires because the 16s are worn out, and you plan to keep the car a long time. It may improve the ride slightly. However, I would recommend buying a ScanGuage. It will give you instant and current fuel economy and help educate you on eco-driving. (I tried an UltraGuage and it does not work well with the diesel)

[cRiPpLe_rOoStEr]

Old-school Diesels are better suited to operate at constant RPM, and to do so for longer times to take some benefit after the longer time they take to warm-up, while the newer ones have been reviewed in order to allow for lower operational temperatures since it would be good to reach these temperatures more quickly and also decreases the NOx emissions.

Common-rail setups have an important role on that matter as the higher pressures and more accurate injection control with their pre-injection and post-injection cycles also improved thermal management, and can even help to overcome the turbo-lag. Having turned the Diesel driving experience closer to the gassers, some common-rail engines can even benefit from idle shut-off and other hypermiling techniques that wouldn't be so effective in an old-school Diesel.

[mcbota]

Originally Posted by COcyclist

In my opinion it would take a long time to recoup your investment unless you need to buy tires because the 16s are worn out, and you plan to keep the car a long time. It may improve the ride slightly. However, I would recommend buying a ScanGuage. It will give you instant and current fuel economy and help educate you on eco-driving. (I tried an UltraGuage and it does not work well with the diesel)

Is this ScanGauge so important even fi I have board computer? It helps so much? Is there anu source for the best price, including shippping worldwide, more specific to Romania?

[oldtamiyaphile]

Originally Posted by cRiPpLe_rOoStEr

Having turned the Diesel driving experience closer to the gassers, some common-rail engines can even benefit from idle shut-off and other hypermiling techniques that wouldn't be so effective in an old-school Diesel.

I know some diesels now have Stop-Start, but I wonder about how the DPF will handle that kind of mistreatment. I realise that idling isn't really helping keep DPF temps in the butter zone. I'm still tracking my DPF regen frequency, once I get some data, I'll try a bit of engine off and see if I get more frequent DPF burns.

[oldtamiyaphile]

Originally Posted by mcbota

Is this ScanGauge so important even fi I have board computer? It helps so much? Is there anu source for the best price, including shippping worldwide, more specific to Romania?

IMO, sort of. If you want to aim for 80% load, only a SG (etc) can do it. I'm just learning to speak diesel and so far, I've found the 80% method to work (hasn't worked for my on petrol cars in the past). If you drive low in the RPM band it's easy to overdo load (which can lead to ovaled cylinder bores) on a TDI without the load display. On a drive by wire car the ECU should prevent damage but that depends on how conservatively they've set it. My understanding is that my alloy block 2.5 TDI cannot be rebored/ sleeved so I'm being cautious (and I'm hoping it will last me 20 years!).

On the other hand, if your factory display can show both AVG and instant consumption simultaneously (I like having both - if my instant is worse than my AVG, I lift my foot if possible), you can just keep the revs a little (~200rpm) higher and make do. With the SG I can cruise at 1100rpm, load is usually around 70, so it doesn't take much of a hill for load to reach 100. Without SG I'd cruise at ~1300 to have a little more of a safety margin (6 speed).

[euromodder]

Welcome to ecomodder !

Originally Posted by mcbota

I own an Audi A4 diesel, 96 KW, and being new here I am very interested which are the best methods to increase fuel, hypermiling especially in city.

One of the things that got my diesel consumption down (previous car), was coasting in neutral .
Car didn't like rolling starts, and ignition key was known weak spot, so no engine-off coasting.


Another trick is to pulse & coast :
Accelerate to a speed that will get you to the next light / corner / turn / ... at an appropriate speed, then put the car in neutral and coast until you get there, repeat.


Drive in the highest possible gear once the engine is warm - I could do 30kph in 4th

If you have CC, it might help even in the city.

Use the lightest weight oil approved for your car .
If it can use 0w30 instead of 5w40 , use 0w30 .


If you do a lot of city driving, dump any excess weight that may be in your car.

I use to downhill on my trip to work in the morning, when the car is not warm.

That's OK, if the speed doesn't build up too much

Which is the best method to coast: in gear or neutral?

Depends on the conditions :
if you have to slow down anyway or keep speed in check going downhill: in gear
if you want to roll as far as possible / without as little speed loss as possible : in neutral

It is worthy to put something in fron of the radiator, even in the spring-summer time?

It reduces the amount or air going into the engine compartment (and back out), and in doing so, reduces aerodynamic drag.

Do keep an eye on engine temperature though.
You want to have a warm diesel engine, not one running too hot.
Fresh intake air is best, except in a cold winter.

[euromodder]

Originally Posted by mcbota

Also I am thinking if is worthy to change the wheels, in this moment I have 215/55/16 and I want to change with 195/65/15, but I am not sure how much I will gain!

When they need to be changed, chose tyres with low rolling resistance.
A (rare !) or B rated for fuel efficiency on the EU tyre label.

Only change the tyres or wheels when you really have to (when worn or damaged).
You won't get back what it's costing you to change the tyres and/or wheels.


Used tyres and wheels typically don't fetch much money when you sell them, so when buying them new, you lose money on the deal.

If you can buy decent new wheels second hand, that's an option.

If you're buying different wheels, pick lighter wheels, especially for city driving.



Depending on what your greater concern is, money of fuel burned, you can pick a tyre that lasts a lot longer but uses a wee bit more fuel - making a tyre also costs resources.

[euromodder]

Originally Posted by mcbota

Is this ScanGauge so important even fi I have board computer? It helps so much? Is there anu source for the best price, including shippping worldwide, more specific to Romania?

I've had very little succes with a ScanGauge on my Volvo diesel
(Peugeot / Citroen 1.6 HDi engine)

It didn't get calibrated to the car's fuel consumption, I've always felt it got calibrated to the way I drove the car ...


I still have it lying around, feel free to make an offer .

[COcyclist]

Originally Posted by euromodder

Do keep an eye on engine temperature though.
You want to have a warm diesel engine, not one running too hot.

I like to monitor intake air temperature on a turbo car and actual water temperature. In modern cars the temperature gauge stays in one spot (190º F on my Golf) after warm-up. The ScanGauge will show what is really going on.