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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #1 ·
I fear I need to eat my words posted in:

https://www.alfaowner.com/Forum/gen...nced-efficiency-modeandquot.html#post17413037

Last week, the view I held was that in advanced efficiency mode the 3 activated cylinders producing the power required to maintain a steady 110kph would consume give or take the same amount of fuel as 6 active cylinders producing the same total amount of power at the same steady speed on the same road.

However, having just looked properly at the MES logs recorded over a year ago in my Giulia Quadrifoglio during constant speed runs on the M5 I find that with cylinders deactivated the engine actually appears significantly more efficient. I admit I am at a loss to explain why this would be.

I did three runs with the cruise control set to 70 mph one each in A, N and D using MES to log the data from the Bank 1 (ie cylinders 1,2 and 3) ECM.

Note it is Bank 1 always which gets deactivated.

The Air Flow (kg/hour) parameter dropping to zero is, I believe, the clear indication the bank has been deactivated.

Also note that the data shows that cylinder deactivation, at steady motorway speed, occurs about the same proportion of time whether you are in A, N or D. That is contrary to the information published by AR that cylinder deactivation occurs in A and N, but not D.

In my 3 runs, it was 81% in the A run, 77% in the N run and 72% in the D run. Subject to the natural variations, I’d regard those as about equal.

Unsurprisingly therefore, the average consumption was very similar across the three runs.

A was about 38 mpg, N and D were both ~40mpg.

However, whilst the airflow was zero the fuel usage as shown by the Fuel Consumption parameter was about 7.5 litres per hour. Whilst when the airflow was non zero (typically at least 40 kg/hour) the fuel usage was about 10 litres per hour. Note the Fuel Consumption parameter is the consumption of the whole engine NOT just that of Bank 1.

When the cruise control is set to 70 mph MES logs the speed actually as 110 kph. Imperial to metric conversion errors in the cruise control software I believe.

7.5 litres per hour at 110 kph equates to ~ 42mpg

and 10 litres per hour to ~ 31mpg

The conclusions to draw would seem to be that at steady motorway speed:

  1. cylinder deactivation activated gives about 30% better fuel consumption than cylinder deactivation deactivated
  2. economy in A, N and D differ little because each use cylinder deactivation about the same proportion of time
Everything must be taken with health warnings. My data is over a year old and is based just on just 3 runs each of a little under 10 minutes duration. I’ve had 2 software updates since this data was collected.

I'm happy to share my data and Excel plots with anyone desiring them.

After the next software update, I’ll try to log some data which may give more valid results.

Andy
 
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Andy. Thanks for your insightful post. I was not aware de activation was occuring in the other modes, but this now makes complete sense as I have been seeing similar gas mileage on teh open road between the various modes (averaging 8.6km per litre which for our hilly topography is very good for such a car). I chose some time ago to run in D road on the open road, mostly as its safer for when you may need power at little notice to avoid a situation or over take a slow moving vehicle. In A mode you could get caught out very badly. N is fine but I prefer the saftey net of having the immediate response of D to kick down the gears if really needed. I found very small varianced in fuel mileage between A, N and D in these modes (particualrly A and N). Of course A is very good (gets to around 8km per L) because of the coast function and the over drive gear (7th). I was originally under the impression deactivation only worked in A mode so thats for clearing that up...
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #3 ·
Andy. Thanks for your insightful post. I was not aware de activation was occuring in the other modes, but this now makes complete sense as I have been seeing similar gas mileage on teh open road between the various modes (averaging 8.6km per litre which for our hilly topography is very good for such a car). I chose some time ago to run in D road on the open road, mostly as its safer for when you may need power at little notice to avoid a situation or over take a slow moving vehicle. In A mode you could get caught out very badly. N is fine but I prefer the saftey net of having the immediate response of D to kick down the gears if really needed. I found very small varianced in fuel mileage between A, N and D in these modes (particualrly A and N). Of course A is very good (gets to around 8km per L) because of the coast function and the over drive gear (7th). I was originally under the impression deactivation only worked in A mode so thats for clearing that up...
My pleasure, I am rather annoyed that D permits cylinder deactivation as would like to a way to prevent it ever kicking in. My objection being that I feel that one bank and one turbo doing less work than the others can't be a good thing for engine longevity. Assymetrical thermal effects surely have to be bad to some degree.

To be realistic though I'd not expect Cylinder Deactivation to happen much in D. One can understand it being roughly equal occurrence in D as N or A at steady speed on the motorway, but on other roads I doubt if it kicks in much except in A.

Really sorry to hear about the tragic events in Christchurch. Is that far from you?

Andy
 

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Yes truely tragic Andy for our little country which has always prided itself on having relatively few gubs and shootings. Looks like we just joined the big boys on the mass murder record charts - a real trevesty especially for the familys affected!

Like you Im a bit annoyed about the deactivation in D and particularly N to be honest. I was cycling to A occassionally but always mindful I didnt want to spend long periods of time there for the same reasons you state. I cannot believe its possible for sustained periods of deactivation not to have an unbalanced affect on engine longevity over time. I will now exclusievely use D on the open road even though it does give a fuel mileage decifict comapred to A and N because I understand that deactivation will only occur over 100 kmph is a small throttle input is used (I recall something like under 20% TPS from your orginal data IIRC). In D mode I an typically cycling the throttle more often as the gearing is lower. Race mode is now of course the only mode where I guess its not working? I recall from somewhere that with low TPS, warm engine, speed above 100kmph the deactivation only occurs for up to 200 seconds at a time...
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #6 ·
Yes truely tragic Andy for our little country which has always prided itself on having relatively few gubs and shootings. Looks like we just joined the big boys on the mass murder record charts - a real trevesty especially for the familys affected!

Like you Im a bit annoyed about the deactivation in D and particularly N to be honest. I was cycling to A occassionally but always mindful I didnt want to spend long periods of time there for the same reasons you state. I cannot believe its possible for sustained periods of deactivation not to have an unbalanced affect on engine longevity over time. I will now exclusievely use D on the open road even though it does give a fuel mileage decifict comapred to A and N because I understand that deactivation will only occur over 100 kmph is a small throttle input is used (I recall something like under 20% TPS from your orginal data IIRC). In D mode I an typically cycling the throttle more often as the gearing is lower. Race mode is now of course the only mode where I guess its not working? I recall from somewhere that with low TPS, warm engine, speed above 100kmph the deactivation only occurs for up to 200 seconds at a time...
All supported, but ...

The published info from AR which has been posted by others on this Forum declares clearly that Cylinder Deactivation doesn't happen in D. My evidence shows that to be incorrect.

How much of the other information we've gleaned over time, eg the 100kph, can be relied on, I wonder.

Yes we can be sure that cylinder activation doesn't arise with wider throttle openings and at higher speeds, but I really would like to know the actual criteria employed in the software.

I can make some further deductions from my data, for example periods of deactivation didn't exceed 100 seconds and intervening periods of re-activation could be as short as 3 seconds, but nothing can be reverse engineered with confidence.

The only declared reason which I've seen for the gaps between periods of deactivation is to keep the cats hot. However, other considerations like one turbo being idle for 80% of the time at motorway speeds might have been ignored by designers.

What am I planning next.

I think I'll do some MES logs of normal drives in D to see just how often deactivation occurs in a more realistic scenario.

My macbook's battery lets me log for in excess of a hour before it dies on me. So I can log quite a long drive probably as soon as Tuesday. I'd then like to repeat that in N and see if there's much difference.

Before I take any drastic action, I'll get the car's software updated and see if anything changes.

I might approach Celtic Tuning and ascertain how easily they could disable cylinder deactivation in all modes except A.

Andy
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #8 ·
this is (part of) what's mentioned in the training manual re deactivation.....
No mention of driving modes at first glance...
Many thanks jwq,

That's a better description of cylinder deactivation in the Quadrifoglio engine than I've ever seen before, but as you say there's no mention of D, N, A differences.

This paper would suggest that a simple 'fix' might be to modify the CDCM software so that it can only issue the deactivate request in A or, if one prefers, in N as well.


Andy
 

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Good stuff jwq! Do you have the 2.0 training manual? Thanks
 

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Good stuff jwq! Do you have the 2.0 training manual? Thanks
No, I wish I did, as I also have a 2.0....
Looking at the USA Mopar tech site, I think it is available, but it's a bit of a gamble, as you can't see beforehand what you're buying, as it's only available in paper form.....
I'm gambling that it might be this:
https://www.techauthority.com/en-us/products/81-699-16005

there might also be a European equivalent I guess :
https://www.technicalinformation.fiat.com/tech-info-web/acquisto/catalog.do

Price via the USA site incl. shipping is ridiculous though, a $28,- manual becomes $122,- incl.shipping.... :(
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #12 ·
Here's the full document.... Page 212 onwards covers cylinder deactivation....
training manual.pdf
A very interesting publication, not least the section on torque vectoring.

Also I now realise just how sophisticated the Quadrifoglio engine is. Its complexity is beyond the average UK technician's experience. No surprise that when one shows faults it can take a while to get it fixed.

I do wonder if my original intention of keeping my Quadrifoglio 10 years will be feasible. Only time will tell.

Andy
 
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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #13 ·
...
I think I'll do some MES logs of normal drives in D to see just how often deactivation occurs in a more realistic scenario.
...
Andy
I've now logged ECM1 data using MES during a drive in D over a mix of roads lasting about 70 minutes. Mainly the A46 (part of which is dual carriageway) from close to Stratford and then a 30 mile stretch of the M5. For as much as possible and to the extent permitted by the traffic conditions, I was trying to drive at a steady speed without use of cruise control.

Air Flow was zero, indicating cylinder deactivation was in effect, 51% of the time. Cylinder deactivation occurred at speeds from 24 to 143 kph. My top speed was 154 kph.

The proportion of time cylinder deactivation was in effect in each 5 kph cell is illustrated in the attached plot.

For example, when travelling at between 80 and 85 kph deactivation was in effect 91% of the time and between 140 and 145 kph 27%.

The more I look into cylinder deactivation's operation in D, the less I like it when viewed from an engine longevity perspective. Yes on the basis of earlier work, fuel consumption in D might be a much as 30% worse if deactivation wasn't employed in D.

Andy
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #15 ·
Too much info isn't always a good thing. If you hadn't done these tests you'd be none the wiser and you'd be perfectly happy.
Not true at all. At the Millbrook sessions I was keen to find out how Cylinder Deactivation worked, or more importantly when it was in effect, and Naz, bless her, couldn't provide any info at all.

So I chose to find out and I've proved the info published by AR that cylinder deactivation doesn't occur in Dynamic is incorrect.

OK call me a nosey b*****,

Andy
 

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Well done Andy. Makes you wonder what else weve seen published is incorrect (like what modes activate what throttle maps, brake behavious and such like!). I assume from what you have gleened from your own research that Race mode is teh only mode left by which we do not get mandatory de activation? Im a bit suprised to learn that the car is running o 3 cyclinders as slow as 24 kmph and s very active at the target range I spend alot of time. I really thought I would have been able to tell (sound or feel) when the car is on 3 cylinders but confess I cannot really ever since i owned the car. Goes to show how well they have disguised it! The gas mileage on a long open road cruise always seemed a bit mystic to me - what alchemy is at work that allows me to drive a 1900kg 500 bhp performance car (with passenger and baggage) for 600km on a single 58L (which I believe is again incorrect - i swear I have filled the tank with 60L more than once - unless our pumps are a scam over hear...). Now I know! Im really driving a 250 bhp 3 cyclinder car...

I think Alfa have been less than accurate from the get go. I have the pre launch brochure that states in big bold letters a weight that they never got close to (even in maual form), and a weight distribution (50:50) which is not correct (been weighed on scales by numerous US publications more like 52:48).

The only thing I think they did not exagerate is the power which from my perspective (I have another 500 bhp car as comparison) feels like its under reported at least on the torque front.
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #18 ·
Well done Andy. Makes you wonder what else weve seen published is incorrect (like what modes activate what throttle maps, brake behavious and such like!). I assume from what you have gleened from your own research that Race mode is teh only mode left by which we do not get mandatory de activation? Im a bit suprised to learn that the car is running o 3 cyclinders as slow as 24 kmph and s very active at the target range I spend alot of time. I really thought I would have been able to tell (sound or feel) when the car is on 3 cylinders but confess I cannot really ever since i owned the car. Goes to show how well they have disguised it! The gas mileage on a long open road cruise always seemed a bit mystic to me - what alchemy is at work that allows me to drive a 1900kg 500 bhp performance car (with passenger and baggage) for 600km on a single 58L (which I believe is again incorrect - i swear I have filled the tank with 60L more than once - unless our pumps are a scam over hear...). Now I know! Im really driving a 250 bhp 3 cyclinder car...

I think Alfa have been less than accurate from the get go. I have the pre launch brochure that states in big bold letters a weight that they never got close to (even in maual form), and a weight distribution (50:50) which is not correct (been weighed on scales by numerous US publications more like 52:48).

The only thing I think they did not exagerate is the power which from my perspective (I have another 500 bhp car as comparison) feels like its under reported at least on the torque front.
I can't believe cylinder deactivation could occur in RACE, but I've not got the data to prove it. I might do some RACE runs at a steady speed just to see how much worse consumption is.

The greatest distance I've done is 368 miles or 588 km on 53 litres. Most I've ever got in the tank is 55 litres, but I always going looking for a service station as soon as the last segment lights up red.

Andy
 

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Giulia Quadrifoglio Feb 2017 Alfa Rosso, Fiat 500e Apr 2021
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Discussion Starter · #19 ·
Having finally got the ECU software in my 2017 Quadrifoglio updated (see https://www.alfaowner.com/Forum/alf...tesrt-ecu-software-versions.html#post17535479) I've done one run on the M5 in D logging data with MES.

This was sufficient to confirm cylinder deactivation still happens in D. Shame!

I need to do a few more runs to see whether cylinder deactivation occurrence has changed in anyway, but it was sufficient to show that with cruise control set to 70mph in D cylinder deactivation can occur.

Andy
 
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