Mpg dropped considerably in the past week...

Pete_901 · 27th February 2018, 19:55

Mg zt-t cdti. Was averaging 47 mpg now I can barely get it to go over 35 mpg? Usually get about 230 miles for £30. This week I’ve got about 150 miles tops. Any ideas/commen problems?

NigelOBB · 27th February 2018, 19:55

Cold weather can cause a big drop

Sent from my iPhone using Tapatalk

HarryM1BYT · 27th February 2018, 20:00

Quote:

Originally Posted by NigelOBB

Cold weather can cause a big drop

Which is where a FBH really pays for itself, in getting the engine up to temperature rapidly.

klarzy · 27th February 2018, 21:51

Check your egr system ans intercooler orings... you could be loosing boost pressure...

minimutly · 27th February 2018, 21:57

Check your running temps, maybe the thermostat is stuck open a bit?

T-Cut · 28th February 2018, 10:02

Agree on the running temperature. A sudden change like this is likely caused by the cold weather being too much for the system to cope with. The diesel stats are often on a knife edge of performance and a big drop in ambient temperature is too much to handle. Think about the in-line stat modification. Or if you have that, a replacement unit, preferably an 89C version made by the recommended companies (FirstLine, Wahler, Gates). These are known to be watertight when shut, a common cause of stat under-performance in diesels.

Running Temperature/Diagnostic Mode: https://the75andztclub.co.uk/forum/s...ad.php?t=55585

TC

steve-45 · 28th February 2018, 12:02

Ambient temperature seems to have a big effect on diesels.

During the summer I get 300 miles to the half tank point, but in this very cold weather I am lucky to get 250 - same journeys and driving style. And this is with a FBH......

Pete_901 · 28th February 2018, 12:35

I’ve done my O rings for updated ones and I’ve done the in line stat mod! I have changed my abiant temp sensor last week though because it was reading 22 Degress and now it’s reading normal which is COLD! Il do live data on the coolant temp and report back! Also my egr and manifold is clean

bl52krz · 3rd March 2018, 21:05

I get around 46-48 mpg in the summer just doing reasonably short and middle distances. 50-52 on m/way journeys. Winter time, I have just got 37 mpg doing short journeys. I.E. 1to 3 miles at a time. Fbh works very well but of course burns diesel when working. Lately it has been running all the time on short journeys because of the ambient of around -2 to -7. So lower mpg in winter is normal for other reasons also, like fuel ‘shrinkage ‘.

T-Cut · 4th March 2018, 09:53

Quote:

Originally Posted by bl52krz

So lower mpg in winter is normal for other reasons also, like fuel ‘shrinkage ‘.

That's interesting. Does it mean you get more juice (by weight) for your money when filling up in winter?

TC

27th February 2018, 19:55	#1
Pete_901 Regular poster Mg Zt Dark Fantasy 6/7 Join Date: Jun 2016 Location: Birmingham Posts: 68 Thanks: 0 Thanked 1 Time in 1 Post	Mpg dropped considerably in the past week... Mg zt-t cdti. Was averaging 47 mpg now I can barely get it to go over 35 mpg? Usually get about 230 miles for £30. This week I’ve got about 150 miles tops. Any ideas/commen problems?

27th February 2018, 19:55	#2
NigelOBB This is my second home 04 Rover 75 Contemporary SE - 53 Rover 75 Connoisseur -94 Mercedes W140 - 72 VW Beetle 1300 Join Date: Sep 2012 Location: Sunderland Posts: 4,767 Thanks: 1,379 Thanked 493 Times in 429 Posts	Cold weather can cause a big drop Sent from my iPhone using Tapatalk __________________ [SIGPIC][/SIGPIC] Keep smiling - it makes people wonder what you've been up to.

27th February 2018, 21:51	#4
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	Check your egr system ans intercooler orings... you could be loosing boost pressure... __________________ [SIGPIC][/SIGPIC]….All praise Bananaswan….

3rd March 2018, 21:05	#9
bl52krz This is my second home Rover 75 cdt club + Rover 2.5 KV6 Conni SE Join Date: May 2008 Location: Birmingham Posts: 11,394 Thanks: 6,587 Thanked 2,262 Times in 1,729 Posts	I get around 46-48 mpg in the summer just doing reasonably short and middle distances. 50-52 on m/way journeys. Winter time, I have just got 37 mpg doing short journeys. I.E. 1to 3 miles at a time. Fbh works very well but of course burns diesel when working. Lately it has been running all the time on short journeys because of the ambient of around -2 to -7. So lower mpg in winter is normal for other reasons also, like fuel ‘shrinkage ‘. __________________ Great Barr, Birmingham.

27th February 2018, 21:57	#5
minimutly Posted a thing or two mg zt Join Date: Mar 2014 Location: cardigan Posts: 1,087 Thanks: 28 Thanked 187 Times in 158 Posts	Check your running temps, maybe the thermostat is stuck open a bit?

28th February 2018, 10:02	#6
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	Agree on the running temperature. A sudden change like this is likely caused by the cold weather being too much for the system to cope with. The diesel stats are often on a knife edge of performance and a big drop in ambient temperature is too much to handle. Think about the in-line stat modification. Or if you have that, a replacement unit, preferably an 89C version made by the recommended companies (FirstLine, Wahler, Gates). These are known to be watertight when shut, a common cause of stat under-performance in diesels. Running Temperature/Diagnostic Mode: https://the75andztclub.co.uk/forum/s...ad.php?t=55585 TC

28th February 2018, 12:02	#7
steve-45 This is my second home Rover 75 Saloon CDTi Join Date: Oct 2015 Location: Belvedere Posts: 4,076 Thanks: 108 Thanked 1,089 Times in 774 Posts	Ambient temperature seems to have a big effect on diesels. During the summer I get 300 miles to the half tank point, but in this very cold weather I am lucky to get 250 - same journeys and driving style. And this is with a FBH......

28th February 2018, 12:35	#8
Pete_901 Regular poster Mg Zt Dark Fantasy 6/7 Join Date: Jun 2016 Location: Birmingham Posts: 68 Thanks: 0 Thanked 1 Time in 1 Post	I’ve done my O rings for updated ones and I’ve done the in line stat mod! I have changed my abiant temp sensor last week though because it was reading 22 Degress and now it’s reading normal which is COLD! Il do live data on the coolant temp and report back! Also my egr and manifold is clean