5 hours ago, Wino said:

What vacuum? Diesels regulate fuel to control power, rather than airflow.

The above post should've been two posts but it merged them. I made a mistake. 

I have to add on the topic that so far EGR delete had significant impact on increasing mpg.

 

It should be also important to note that my EGR didn't seem to have any issues prior to this test. 

 

This is, however, first 140km and I will keep testing it for at least 1000km because there could be some error. 

 

I also have to add that in that small period of time my car has been idling alot (because we had earthquakes) and it was turned on and off many times. 

On 24/12/2020 at 04:13, Wino said:

Diesel engines are a whole different ballgame for EGR.  It will be interesting to see the fuel usage figures after your long trip.

 

 

@DataLog

 

52 mph as opposed to 46 mph on way there with EGR.

 

It felt smoother & more flexible but it's only on returning to my usual journeys that I can really appreciate it. The drive from cold from my house up a hill on very light throttle is so much brisket, it will accept a higher gear earlier, it feels so much smoother and more responsive, none can be measured and all could be confirmation bias but I am happy.

Don't suppose you noticed the wind directions on your long trips? I imagine they would - on average - tend to be more favourable northbound than southbound, so reducing the delta in mpgs, possibly?

Edited 30 December, 20205 yr by Wino

The first two hours of the journey were during the storm that descended from the UK, I was never aware of any wind just torrential rain, my pal said that I would have the Southerly wind behind me but if the storm was moving from North to South would the wind not have been in that direction?

 

At a couple of stops to pour coffee from my flask I noticed tree branches that had blown down but was never aware of any wind.

 

TBH its a big increase in MPG, bigger than when I cleaned all the crud out from the throttle body, a job I will no longer have to do.

 

I'm just about to do an 80km round trip that I regularly do to compare the MPG, that should be more representative.

4 minutes ago, J.R. said:

storm was moving from North to South would the wind not have been in that direction

Winds circle round areas of low pressure and tend to be strong in storms, so depends where you are relative to the centre of the low.  The centre doesn't stay still though, and neither did you. 

 I'm sure I could look up historical met data for both your long journeys, but I can't summon that much interest.   It could be a significant factor though, often neglected.

Long term fill-to-fill mileages are the only real indication.

 

Agreed, I certainly gained 4 or 5 mpg after the throttle body cleaning, since then with covid I have done a lot less mileage and different much shorter journey profiles which will also have had an effect.

 

I will reset the long term mpg readout to zero for a fresh start not influenced by the 1500kms done on the autoroute and the 400kms done in sunday driver mode while there.

 

I started with struggling to average 45mpg in full economy mode & have already got that up to 50mpg and not having to spare the horses, a little more would still be appreciated, with the brick aérodynamiques and the 4x4 its never going to be what the Octavias were but its getting closer.

57.7 mpg, 46 (ish) mile round trip across country B roads with some city driving at destination, at least 5mpg more than ever before and it was from a cold start and 5.5° temperature all the time, my previous mpg figures were summer ones.

 

Driving away from the cold start the fuel consumption shows after I believe its 200m, possibly 300m, its normally showing 18 mpg at that point which is already impressive but today from a cold start it was 25.4mpg and at that point I was selecting 6th gear whereas usually it would have been 5th and had to be held in that gear for the hill just beyond.

 

I think stopping the EGR from functioning has effectively rolled back the emissions fix (done before I had the vehicle) which is criticised for excessive use of EGR.

7 hours ago, J.R. said:

57.7 mpg, 46 (ish) mile round trip across country B roads with some city driving at destination, at least 5mpg more than ever before and it was from a cold start and 5.5° temperature all the time, my previous mpg figures were summer ones.

 

Driving away from the cold start the fuel consumption shows after I believe its 200m, possibly 300m, its normally showing 18 mpg at that point which is already impressive but today from a cold start it was 25.4mpg and at that point I was selecting 6th gear whereas usually it would have been 5th and had to be held in that gear for the hill just beyond.

 

I think stopping the EGR from functioning has effectively rolled back the emissions fix (done before I had the vehicle) which is criticised for excessive use of EGR.

I think that the best way of testing this is to put a measured amount of fuel in the car and just measure the distance traveled until it's spent.
I don't trust the mpg meter that much... 

I know its inaccurate and has been on all my Skoda vehicles, I recalibrated it with VCDS on my last Octavia but after being lied to for so many years I could not stomach the truth

 

So I recalibrated it to lie again and gave it the maximum correction factor available knowing that the deception would please me!

 

The new owner is still delighted

 

Joking apart (it was all true!) its good as a comparator.

 

I can already see that the last tank has given me at least another 75 miles from the one before, this one is coming to an end so I can do a brim to brim calculation, it will be less than what the maxidot is showing but more MPG than the previous brim to brims have shown.

 

Its only when Covid will be over and my journey profiles are back to what they were before will I be able to have a precise idea of the improvements.

5 hours ago, J.R. said:

 

So I recalibrated it to lie again and gave it the maximum correction factor available knowing that the deception would please me

 

" You want the truth? YOU CAN'T HANDLE THE TRUTH! " 

Thanks for making me picture Jack Nicholson on fine form in A Few Good Men. 

Interesting thread. I tried disconnecting my BBZ EGR for a while to see what would happen in 1000 miles. In my case I didn't notice any gains in fuel economy (which is STILL abysmal, my first post in the forum was about it, 140 km city driving on a full tank until reserve lights up) and noticed an increase in harshness between gear changes, as revs seem to fall much quicker. I felt the car becoming sluggish and requiring more throttle lately, so I decided to plug it in again. Everything is back to normal. 

14 hours ago, juanse_2691 said:

Interesting thread. I tried disconnecting my BBZ EGR for a while to see what would happen in 1000 miles. In my case I didn't notice any gains in fuel economy (which is STILL abysmal, my first post in the forum was about it, 140 km city driving on a full tank until reserve lights up) and noticed an increase in harshness between gear changes, as revs seem to fall much quicker. I felt the car becoming sluggish and requiring more throttle lately, so I decided to plug it in again. Everything is back to normal. 

Interesting.
I have seen that many newer cars have ECU restriction if EGR is disconnected. In my case there was no noticeable effect on performance, but there is a noticeable effect on fuel consumption. It's not much, but it's measurable.