Mpg only 19 ???????

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My old td5 disco did around 27-28mpg and my 4.6 petrol range rover does 22 at best although 18-20 is the norm.
 
what setting do u put ur syNergy boxes on for max mpg please, mines an auto and whAt setting do u put the switch on, red or green thks again

gary
 
may i ask what can cause poor mpg
Click to expand...

friction drag .. .. particularly before the engine and oil have reached optimum temps.
( my choice of helper for that .. : ZX1 Home )
dirty crankcase vent system .. resulting in excessive crankcase pressure ( more 'work' for the engine )

inneficient fuel combustion :

dirty injector nozzles .. ( or faulty injectors )
fuel contaminants such as water
( to combat those .. i use .. http://www.landyzone.co.uk/lz/2409712-post6.html )
dirty air filter
faulty MAF that might cause ovefuelling ..

sticking egr valve .. ( where fitted )

faulty air intake temp sensor causing a default of -5c to be used by the ecu ..
faulty coolant temp sensor .. that would Probably effect injector timing in theory
faulty glow plug system ( inneficient combustion on cold start up )

faulty turbo actuating system .. although by how much that would effect mpg i not be sure
i.e. for an 'overboost' the ecu would cut the fuel supply to a safe level ..
for an 'underboost' .. in theory the ecu would see not enough manifold pressure / air-mass to supply desired fuel ..
although would have thought anything that detracts from efficiency could potentialy waste fuel

a faulty coolant thermostat that caused the engine to run too cold would effect mpg

low cylinder compression

~~~~~~~~~~~~~~~

the ecu needs accurate readings of air temp. / coolant temp / air mass / manifold pressure
to compute fuel delivery / injector timing for a particular go-pedal 'demand' ..

if the sensors were to give the wrong readings .. the ecu could supply/inject more fuel than needed for optimum combustion .. therefore wasting fuel ..
and / or .. provide the wrong injector timing .. again wasting combustion energy ..

disclaimer: i don't know the particulars of the td4 engine mapping .. or 'defaults'
but on investigation .. many common rail diesel engines with computerised management systems
have certain things in common to provide best fuel combustion for a given power demand

~~~

obviously many of the above .. if a 'fault' .. would .. or might .. show other symptoms ..
rough idling .. lack of power .. etc etc

~~~~

use of the PTI heater causes the idle rpm to rise .. adding to fuel consumption ..
same for .. if the ecu sees high electric consumption for some other reason ..
i.e. idle rpm raised to compensate for load on the alternator ..

~~~~~~~~~~~~~~

overall condition of the drive train .. clutch / gears / vcu / diffs ..

tyre pressure ..

aerodynamics ..

driving habits ..

what 'ianjones' said regarding the vcu / tyres .. post no. 21 .. makes sense .. :)
 
hd3 said:
friction drag .. .. particularly before the engine and oil have reached optimum temps.
( my choice of helper for that .. : ZX1 Home )
dirty crankcase vent system .. resulting in excessive crankcase pressure ( more 'work' for the engine )

inneficient fuel combustion :

dirty injector nozzles .. ( or faulty injectors )
fuel contaminants such as water
( to combat those .. i use .. http://www.landyzone.co.uk/lz/2409712-post6.html )
dirty air filter
faulty MAF that might cause ovefuelling ..

sticking egr valve .. ( where fitted )

faulty air intake temp sensor causing a default of -5c to be used by the ecu ..
faulty coolant temp sensor .. that would Probably effect injector timing in theory
faulty glow plug system ( inneficient combustion on cold start up )

faulty turbo actuating system .. although by how much that would effect mpg i not be sure
i.e. for an 'overboost' the ecu would cut the fuel supply to a safe level ..
for an 'underboost' .. in theory the ecu would see not enough manifold pressure / air-mass to supply desired fuel ..
although would have thought anything that detracts from efficiency could potentialy waste fuel

a faulty coolant thermostat that caused the engine to run too cold would effect mpg

low cylinder compression

~~~~~~~~~~~~~~~

the ecu needs accurate readings of air temp. / coolant temp / air mass / manifold pressure
to compute fuel delivery / injector timing for a particular go-pedal 'demand' ..

if the sensors were to give the wrong readings .. the ecu could supply/inject more fuel than needed for optimum combustion .. therefore wasting fuel ..
and / or .. provide the wrong injector timing .. again wasting combustion energy ..

disclaimer: i don't know the particulars of the td4 engine mapping .. or 'defaults'
but on investigation .. many common rail diesel engines with computerised management systems
have certain things in common to provide best fuel combustion for a given power demand

~~~

obviously many of the above .. if a 'fault' .. would .. or might .. show other symptoms ..
rough idling .. lack of power .. etc etc

~~~~

use of the PTI heater causes the idle rpm to rise .. adding to fuel consumption ..
same for .. if the ecu sees high electric consumption for some other reason ..
i.e. idle rpm raised to compensate for load on the alternator ..

~~~~~~~~~~~~~~

overall condition of the drive train .. clutch / gears / vcu / diffs ..

tyre pressure ..

aerodynamics ..

driving habits ..

what 'ianjones' said regarding the vcu / tyres .. post no. 21 .. makes sense .. :)
Click to expand...

blimey thks buddy, i did ask didnt i lolol

ive got to load a software program similar to the hawkeye so hopefully that will tell me if ive got any faulty sensors etc, will make sure i turn off the synergy box, was just going to turn the switch to the middle setting

am pleased i listened to u guys in not spending money on rebuilding another engine but using the money instead of giving my car a really good service etc

appreciate all the help

gary
 
should have added that ..

i can't comment regarding an auto-gearbox .. mine's a manual ..
and the auto's seem to have their particular foibles as to when-to-change-gear
although if i had one .. i'd probably use the manual-sport-shift-option ..
or whatever it is that enables the driver to choose which gear at what rpm ..

( no doubt the operational efficiency of the auto box would effect mpg ..
( i.e. whatever it does to transfer torque /power to the wheels

and ..

i've not a clue regarding my mpg as far as 'multiple short trips / city driving' is concerned
as my weekly driving routes don't involve much of that as a percentage of the total ..
 
Last edited:
the only proper way to check you fuel is to brim the tank, put on your trip meter to zero, and the do some milage and then brim you tank again, and see what miles you have done then divide the milage by the ltrs then times that by 4.54 and thus you will get the answer , it is no use saying how many miles you get for £50 as the price keeps going up,
 
Phil E said:
I got an app called 'Road trip' a few months ago & was shocked to discover I was only doing 22 mpg. I can be quite heavy footed & will often use the kick down. I drove the next tank very steady & was pleased to push it up to 26mpg, all based on town driving & short cold trips. I went on a 400+ trip & got 35mpg driving a very steady 60-70mph there. On the way back I got 28mpg driving 70+
No synergy fitted, EGR valve not blocked, TD4 auto

Hope that helps as a comparison
Click to expand...

Downloaded the same App and also surprised with a poor mpg figure (just under 25). The occasional Mway trip gives me about 35 and that's with the EGR bypass and Synergy 2a with new MAF and in cab switch ( synergy set to 6 and switch on green).
 
hd3 said:
should have added that ..

i can't comment regarding an auto-gearbox .. mine's a manual ..
and the auto's seem to have their particular foibles as to when-to-change-gear
although if i had one .. i'd probably use the manual-sport-shift-option ..
or whatever it is that enables the driver to choose which gear at what rpm ..

( no doubt the operational efficiency of the auto box would effect mpg ..
( i.e. whatever it does to transfer torque /power to the wheels

and ..

i've not a clue regarding my mpg as far as 'multiple short trips / city driving' is concerned
as my weekly driving routes don't involve much of that as a percentage of the total ..
Click to expand...

The down side to using the manual gear selection instead of D is there is little improvement in mpg :( The box ECU only allows the up change if it thinks there is sufficient engine torque available to run in the gear you are wanting to select!! So basically you push the lever forward to go up to the next gear but as you aren't going fast enough the ECU ignores the requests. I reckon D is a good compromise and I try not to select Sport unless i'm in a hurry. The other thing the auto box does is allow the box to drop to many gears on Kick down which is very annoying as running a V6 at 6,000 rpm is a costly business!!
 
cowshat said:
Sorry manual . Has a synergy chip on , on Eco I've a heavy right foot but our lass drives it more and she definitely hasn't . 220 miles to 50 quid think I worked it out right . Mixed driving
Click to expand...

50 quid equates to approx 34 litres, or 7.5 gallons. 220 miles from 7.5 gallons is about 28 mpg, not 19.
 
originaly posted by Nodge68:
So basically you push the lever forward to go up to the next gear but as you aren't going fast enough the ECU ignores the requests.
Click to expand...

oh :(

my immediate thought .. was .. a potential gearbox ecu remap ..
i did do a google search .. and came up with a blank ..
ppl on the rover mg-forum were sayin' it can't be done .. at least not d.i.y.

( cheers for the info. :)
 
Blooming heck 8 miles is long distance for me nowadays, my average is about 1 miles to Tesco. I'm sometimes forced to drive to Marks and Sparks but need the Sat Nav for that, will soon have to use the M5 so will have to swat up in the Highway Code :)
 
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