High Fuel Consumption - Page 2

StevenWilliams · 29th December 2009, 12:41

Quote:

Originally Posted by ianfletcher1979

I put atleast £40 a week in which fills me up to about 3/4 of a tank and its as soon as i drive it starts to drop. I can be doing 70 on the motorway with the cruise control on and even then i only get about 120 miles from the fuel. It was fine a couple of months ago but then i noticed a big difference but i just put that down to the actuator arm in the inlet because it was coming loose but i have replaced it with a new unit and its still the same. I have checked for fuel leaks and exhaust leaks but not finding anything wrong. I have noticed the engine is a bit shakey whilst idleing instead of being smooth like it should be.

I'd fill it up and drive it until it needs refilling (Fuel needle at the bottom not just the light..

Take a spare 5l can of the go juice in the boot just in case but it doesn't sound to far out if the guage is not behaving properly.

T-Cut · 29th December 2009, 13:04

One factor not mentioned so far is running temperature. Any case of poor fuel economy should have the running temperature checked as well. I'd do a diagnostics check while driving and see exactly what's happening to the temperature. The temperature gauge is of course useless.

TC

JohnDotCom · 29th December 2009, 13:07

As TC says,
The Diesel should run at 89C much less and the Thermostat needs replacing.
Ideally temperatures should be in the 90C or slightly higher but the design seems to have it running lower.

The Gauge will say fine from about 83C for some reason.

I'm not sure of the figures off hand for Petrol but I know TC is around.

T-Cut · 29th December 2009, 14:08

The optimum running temperature for all engines is said to be in the 95 -100C range. Diesels tend to run cooler and would benefit (IMO) from a 90-92C thermostat. Petrol models usually run in this range OK when everything's operating properly. The weather/ambient temperature should have minimal effect if the stat is fully functional.

TC

kaiser · 29th December 2009, 17:42

If your engine is shaking while idling, then your combustion is uneven, indicating a timing or mixture problem.
Your temperature signal to the computer could indicate a low temperature, which will enrichen the mixture as if on choke. A similar fault could be caused by a faulty pressure sensor in the inlet manifold. This last sensor is very sensitive to compressed air. If your mechanic has been in there for cleaning with compressed air, your sensor could be scrap.
This will cause unburnt fuel in, and smell from exhaust and also the trembling/stuttering of the engine.
I would go and get it cheked on the T4!!

brownie21 · 29th December 2009, 18:01

Your in-tank fuel filter housing may have come loose (under the rear seat)
Plenty of posts and how to's on here, think T-Cut is the expert!

kaiser · 29th December 2009, 18:04

Brownie, seriously, what is in that punch>>>

A loose filter means less or no petrol, that does not exactly match heavy consumption now, does it.??

ianfletcher · 29th December 2009, 21:53

Could air in the coolant system cause a problem because i have noticed that when i take the cap off the expansion tank i can hear a hiss of air as though the system wasnt bled properly?

ianfletcher · 29th December 2009, 22:22

Quote:

Originally Posted by T-Cut

I'd do a diagnostics check while driving and see exactly what's happening to the temperature.

TC

How do i do a diagnostics check whilst driving?

ianfletcher · 29th December 2009, 22:46

Never mind. Just found out you mean via the ipk so will check it tomorrow and report back the reading.

29th December 2009, 13:07	#13
JohnDotCom * Rover 75 FaceLift Tourer CDTi 170BHP Auto ConnSE 2005 Model Starlight Silver Join Date: Nov 2006 Location: Abergele Posts: 28,735 Thanks: 0 Thanked 6 Times in 5 Posts	As TC says, The Diesel should run at 89C much less and the Thermostat needs replacing. Ideally temperatures should be in the 90C or slightly higher but the design seems to have it running lower. The Gauge will say fine from about 83C for some reason. I'm not sure of the figures off hand for Petrol but I know TC is around. Last edited by JohnDotCom; 29th December 2009 at 16:34..

29th December 2009, 18:01	#16
brownie21 Gets stuck in Rover 75 Saloon 1.8T Club SE Join Date: Dec 2007 Location: Huddersfield Posts: 521 Thanks: 0 Thanked 0 Times in 0 Posts	Your in-tank fuel filter housing may have come loose (under the rear seat) Plenty of posts and how to's on here, think T-Cut is the expert! __________________ Wayne [SIGPIC][/SIGPIC] We all have mental problems, it's just that some of us choose to show them.

29th December 2009, 13:04	#12
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	One factor not mentioned so far is running temperature. Any case of poor fuel economy should have the running temperature checked as well. I'd do a diagnostics check while driving and see exactly what's happening to the temperature. The temperature gauge is of course useless. TC

29th December 2009, 14:08	#14
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	The optimum running temperature for all engines is said to be in the 95 -100C range. Diesels tend to run cooler and would benefit (IMO) from a 90-92C thermostat. Petrol models usually run in this range OK when everything's operating properly. The weather/ambient temperature should have minimal effect if the stat is fully functional. TC

29th December 2009, 17:42	#15
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	If your engine is shaking while idling, then your combustion is uneven, indicating a timing or mixture problem. Your temperature signal to the computer could indicate a low temperature, which will enrichen the mixture as if on choke. A similar fault could be caused by a faulty pressure sensor in the inlet manifold. This last sensor is very sensitive to compressed air. If your mechanic has been in there for cleaning with compressed air, your sensor could be scrap. This will cause unburnt fuel in, and smell from exhaust and also the trembling/stuttering of the engine. I would go and get it cheked on the T4!!

29th December 2009, 18:04	#17
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	Brownie, seriously, what is in that punch>>> A loose filter means less or no petrol, that does not exactly match heavy consumption now, does it.??

29th December 2009, 21:53	#18
ianfletcher I really should get out more....... BMW 1 series Join Date: Oct 2008 Location: Bolton Posts: 2,094 Thanks: 12 Thanked 40 Times in 36 Posts	Could air in the coolant system cause a problem because i have noticed that when i take the cap off the expansion tank i can hear a hiss of air as though the system wasnt bled properly?

29th December 2009, 22:46	#20
ianfletcher I really should get out more....... BMW 1 series Join Date: Oct 2008 Location: Bolton Posts: 2,094 Thanks: 12 Thanked 40 Times in 36 Posts	Never mind. Just found out you mean via the ipk so will check it tomorrow and report back the reading.