TDI mpg vs engine temp

[lloydy]

Plain dangerous. Someone seems to have serious concentration issues, or does not have the ability to finish a job 100%

[Mudlark]

For what its worth:

The only time i get good MPG is in hotter climes with longer average continuous drives.

Summer of 2010 in Croatia 28mpg (4700km)
Summer of 2011 UK 25MPG (1200Km)
Summer of 2012 France 29.5 MPG (4200Km)

This summer I was particularly well chilled out being away in the van, with the lovely Linda, on our lonesome, for the first time in 21 years. (The van knows you know )

Got every fill, brim, litre and kilometre logged since May 2010 which I can list up if wanted. Those are peak MPG's that coincide with holidays; the rest of the time 24-25MPG is typical.

Watching the discussion with interest as any thermostat or tweak that can get the MPG up is welcome so more power to your endeavours....crate of beer to the you if you ever get me up over 35MPG I just need to be able to turn up at a partner garage and order the Lloydy AFN MPG Mod ....

[HarryMann]

[lloydy]

Mark, do you have a way of checking engine temp? Especially what the ecu reads? Apparently they do go bad and register cooler temps meaning the ecu stays in warm up mode. Only asking as your 28mpg figures is around what I'm getting on short little drives around home. I'm hoping this weekend will prove some of this info I've been reading to be correct, although driving on the lanes might muck that up a bit. Maybe I'll take some figures and refill before going on the lanes.

[Cableguy]

Mudlark, is your AFN bone stock?
Injectors/egr etc

[Mudlark]

Yes as far as I know it is a stock AFN as fitted by Berndt Jaegar almost ten years ago now.

I need to cobble up the notebook running VAGcom and see if I can find the engine temp channel. If its there Ill plot it on a run and see what comes up Lloydy.

[ninja.turtle007]

The issue I had with the original stat was the heater never really blew above luke warm in the winter. The stat was replaced with a 90c stat in the early summer but as yet I have not really been able to test the heater on a really cold day.

[randolph57]

ok
For what its worth here is my data whilst away in France the last two weeks:-

10/09/12 Plymouth to Dover via Busfest Fastish motorway 75+mph 683Kms 55Litres = 35.23mpg
12/9/12 Calais heading south mainly D roads 60-70 mph 562Kms 42.38L = 37.63MPG
20/9/12 IL DE re heading north mainly D roads 60-70mph 453Kms 33.97L = 37.84 mpg
22/9/12 nearing Calais/Abbeyville (hilly + boost pipe off) 505Kms 38.84L = 36.89mpg
I have yet to fill up since arriving back but am sure it will be similar to above being mainly Fast A road once free of the M25!

[randolph57]

I did manage to change thermostat again to one that operated well between 80 and 90 degrees as opposed to the 95+ or 70 degree ones previously tried and had no issues in all conditions.
I previously was getting around 30-32 mpg running in 'warm up mode' so am more than happy with the modest decrease in consumption
especially as the times of higher speed running didn't appear to adversley affect the figures-only issue i had was a boost pipe came loose resulting in a marked power drop-carried on for 50 miles or so to make the campsite rather than stopping and unpacking bikes etc-took 3 mins to fix and normal service resumed.

[HarryMann]

10/09/12 Plymouth to Dover via Busfest Fastish motorway 75+mph 683Kms 55Litres = 35.23mpg
12/9/12 Calais heading south mainly D roads 60-70 mph 562Kms 42.38L = 37.63MPG
20/9/12 IL DE re heading north mainly D roads 60-70mph 453Kms 33.97L = 37.84 mpg
22/9/12 nearing Calais/Abbeyville (hilly + boost pipe off) 505Kms 38.84L = 36.89mpg
I have yet to fill up since arriving back but am sure it will be similar to above being mainly Fast A road once free of the M25

Looks good, but have you got the commensurate odometer figures linking them all up, so we can pump them into the 80-90 Wiki spreadsheet? That is the odo readings, at every brim, ta?

[lhd]

Extra cold fueling apart, does this appl to IDI engines too?
I have the 87 degree thermostat from Brickwerks currently fitted but I have an oil cooler too, do you think i should go back to the standard thermostat?
Rob.

[lloydy]

do you mean you have the 80 degree stat? As 87 is the normal one. I'd keep the 80 degree one in a AAZ. When i had mine it had a oil cooler and 80 deg stat and still ran at 90 deg.
AAZ's run too hot in our vans, so you need that head start that the other stat gives you. Well thats my opinion anyway!

[lhd]

[lloydy]

I did manage to change thermostat again to one that operated well between 80 and 90 degrees as opposed to the 95+ or 70 degree ones previously tried and had no issues in all conditions.
I previously was getting around 30-32 mpg running in 'warm up mode' so am more than happy with the modest decrease in consumption
especially as the times of higher speed running didn't appear to adversley affect the figures-only issue i had was a boost pipe came loose resulting in a marked power drop-carried on for 50 miles or so to make the campsite rather than stopping and unpacking bikes etc-took 3 mins to fix and normal service resumed.

somehow missed this
sounds good then! Around a 5mpg gain
i wouldnt leave it so long next time the boost pipe pops off, as the turbo will be spinning like a nutter which could lead to it failing.
my first refill with the correct stat will be poor i reckon. I have only been doing 1-2 mile drives and its also spent a lot of time on the drive with the engine running for one reason or another.
Seems like you might have had a dodgy stat then, although mine has now dropped from 90 deg to 87 deg in normal driving conditions, so maybe it takes a bit to settle?
excellent news on the mpg

[HarryMann]

Rob, where does your temp needle sit?

Personally I don't think that running cool does you any great favours, as can be seen from the oil temp gauge and water temp gauge as soon as you either start loading the engine up, hill climbing, or increasing revs (or cruising faster, which does both)

Watching these gauges, tells you that any headroom is a matter of a minute or less sometimes, before the inexorable rise in oil and water temp.
I have about 7.5 litres of oil in my AAZ system, and even with that and a 19 row cooler, the oil temp starts rising almost immediately the load goes up, say within 30 seconds. Shortly after the water needle starts moving too, and depending on your installation, the weather etc maybe even the 1st stage fan will come on quite soon.

As long as the thermostat is opening fully, has the correct bypass flow etc, I'm not sure running cold (relative to the accepted 88~92 norm) all the time is a particularly good thing, when any advantage is lost in less than a minute. I may be wrong though. I am also suprised at the range of thermostats available... were all these original VW parts or have been made avialble subsequently