cdti improve mpg

lesron · 12th October 2016, 18:58

Hi all have two cdti s manual saloon 135bhp returns 45+ mpg mainly motorway,
and auto tourer 115bhp 36mpg on the same run, was thinking of having the ecu programed to 160 on the auto anyone know how much improvement to fuel consumption, or are their better options
Cheers

klarzy · 12th October 2016, 19:03

Quote:

Originally Posted by lesron

Hi all have two cdti s manual saloon 135bhp returns 45+ mpg mainly motorway,
and auto tourer 115bhp 36mpg on the same run, was thinking of having the ecu programed to 160 on the auto anyone know how much improvement to fuel consumption, or are their better options
Cheers

I have 2 160's and they both get 45-48 on a run, 36-42 urban

Heddy · 12th October 2016, 19:05

I think the manual mpg improves very little with a re-map, so doubt the auto will. Having said that, the fuel figures certainly don't get any worse after the tune.

Kiltman · 12th October 2016, 19:16

First thing I would be checking is that it is getting up to temperature.

klarzy · 12th October 2016, 19:20

yep,

correct temp (circa 84-90)
Good air filter, PCV filter, Maf in spec, no tuning box to cause overfuel, good oil, good tyre pressures etc.

lesron · 12th October 2016, 19:36

Using onboard computer manual 87
auto 89/92 but the gauge is on max with red light on

Number 6 · 12th October 2016, 19:56

Fuel consumption has always been a bone of contention on this any many other forums.

It will always depend on several factors,Car up to temp,type of roads used,The driver,how well the car is maintained and how big a foot the driver has.

Many will claim astronomical mileages of 60 + per gallon and others will complain of low forties.

If you have the 160 remap (Recommended) then initialy you may find a drop in economy as you explore the new found performance.

But when that wears off and you return to normal the MPG will settle down,and the only way to test it is a Brim to Brim test.

Having said all that My MPG is on average 52 MPG and this is with a 160 re map and over many thousands of miles of different types of roads ect.And doing a Brim to Brim test.

Mike Noc · 13th October 2016, 06:09

Quote:

Originally Posted by lesron

Hi all have two cdti s manual saloon 135bhp returns 45+ mpg mainly motorway,
and auto tourer 115bhp 36mpg on the same run, was thinking of having the ecu programed to 160 on the auto anyone know how much improvement to fuel consumption, or are their better options
Cheers

We have one of each too, and I get the same difference when driving them - around 50 and 38 respectively.

I thought the auto would have been better cruising on long uninterrupted motorway runs when the autobox torque converter is locked up, but the best I ever got was 44 mpg.

Sector-9 · 13th October 2016, 06:40

Even with TC lockup, the engine still has to drive the hydraulic pump which powers the transmission. Also until the torque converter does lock up (which may depend on being in certain gears, above certain speeds or even above certain temperature), there's always some amount of slippage in it, which only happens in a manual when you change gear or are pulling away from standstill. Finally, I don't know if the auto 'boxes are four or five speed, but if four then the fewer ratios will be more of a compromise.

Autos are great for stop/start traffic and smooth rides, but you pay for this at the pumps. Remapping will make the car more enjoyable to drive, but it won't alter the pre-programmed rules for when to change gear and lock up the TC so you'll see less (economy) benefit than a driver of a manual who can take advantage of the extra power by upshifting earlier.

I'd be happy with 44mpg from an auto tourer, but changes in driving style may be able to improve on this- Google hypermiling for hints.

pletevl · 13th October 2016, 06:58

Are you just stating what the on board computer is telling you ? is so, do brim to brim tests.

12th October 2016, 18:58	#1
lesron Avid contributor rover 75 saloon and tourer Join Date: Jul 2015 Location: Hythe Posts: 162 Thanks: 31 Thanked 9 Times in 9 Posts	cdti improve mpg Hi all have two cdti s manual saloon 135bhp returns 45+ mpg mainly motorway, and auto tourer 115bhp 36mpg on the same run, was thinking of having the ecu programed to 160 on the auto anyone know how much improvement to fuel consumption, or are their better options Cheers

12th October 2016, 19:20	#5
klarzy This is my second home none but not gone Join Date: Mar 2013 Location: March, Cambs Posts: 16,437 Thanks: 894 Thanked 4,247 Times in 3,025 Posts	yep, correct temp (circa 84-90) Good air filter, PCV filter, Maf in spec, no tuning box to cause overfuel, good oil, good tyre pressures etc. __________________ [SIGPIC][/SIGPIC]….All praise Bananaswan….

12th October 2016, 19:56	#7
Number 6 This is my second home Rover 75 tourer Club CD/Limo Tints Join Date: Nov 2008 Location: Meneac Posts: 6,759 Thanks: 5,007 Thanked 1,609 Times in 869 Posts	Fuel consumption has always been a bone of contention on this any many other forums. It will always depend on several factors,Car up to temp,type of roads used,The driver,how well the car is maintained and how big a foot the driver has. Many will claim astronomical mileages of 60 + per gallon and others will complain of low forties. If you have the 160 remap (Recommended) then initialy you may find a drop in economy as you explore the new found performance. But when that wears off and you return to normal the MPG will settle down,and the only way to test it is a Brim to Brim test. Having said all that My MPG is on average 52 MPG and this is with a 160 re map and over many thousands of miles of different types of roads ect.And doing a Brim to Brim test. __________________ ] "I started out with nothing, and Ive still got most of it left!"

13th October 2016, 06:40	#9
Sector-9 Gets stuck in Rover 75 CDT manual Tourer Join Date: Aug 2014 Location: nr. Mansfield Posts: 767 Thanks: 24 Thanked 182 Times in 137 Posts	Even with TC lockup, the engine still has to drive the hydraulic pump which powers the transmission. Also until the torque converter does lock up (which may depend on being in certain gears, above certain speeds or even above certain temperature), there's always some amount of slippage in it, which only happens in a manual when you change gear or are pulling away from standstill. Finally, I don't know if the auto 'boxes are four or five speed, but if four then the fewer ratios will be more of a compromise. Autos are great for stop/start traffic and smooth rides, but you pay for this at the pumps. Remapping will make the car more enjoyable to drive, but it won't alter the pre-programmed rules for when to change gear and lock up the TC so you'll see less (economy) benefit than a driver of a manual who can take advantage of the extra power by upshifting earlier. I'd be happy with 44mpg from an auto tourer, but changes in driving style may be able to improve on this- Google hypermiling for hints. __________________ Free fault codes scan/clear (TOAF) - M1 J27 area Last edited by Sector-9; 13th October 2016 at 06:46..

12th October 2016, 19:05	#3
Heddy This is my second home None Join Date: Feb 2013 Location: None Posts: 5,556 Thanks: 465 Thanked 1,161 Times in 924 Posts	I think the manual mpg improves very little with a re-map, so doubt the auto will. Having said that, the fuel figures certainly don't get any worse after the tune.

12th October 2016, 19:16	#4
Kiltman I really should get out more....... MG ZT CDTi 135 / Rover 75 Club SE 160 Join Date: Jun 2011 Location: Leek Posts: 2,013 Thanks: 235 Thanked 128 Times in 104 Posts	First thing I would be checking is that it is getting up to temperature.

12th October 2016, 19:36	#6
lesron Avid contributor rover 75 saloon and tourer Join Date: Jul 2015 Location: Hythe Posts: 162 Thanks: 31 Thanked 9 Times in 9 Posts	Using onboard computer manual 87 auto 89/92 but the gauge is on max with red light on

13th October 2016, 06:58	#10
pletevl Posted a thing or two rover 75 cdti(rhd), MG ZR(lhd), MG TF(lhd), MG TF(rhd), mini mpi (lhd), Renault megane III (awful) Join Date: Mar 2014 Location: East of France Posts: 1,282 Thanks: 124 Thanked 114 Times in 93 Posts	Are you just stating what the on board computer is telling you ? is so, do brim to brim tests.