02 CDT Auto giving 29 mpg

ned78 · 11th August 2010, 23:07

As the subject says, my lovely 02 CDT Auto Tourer is giving me a paltry 29mpg on a good week. Now I do carry a lot of weight, I'd estimate somewhere around 100 kilos in the car permenantly due to my SMART repair business being run out of it. But should it be that poor?

I had the oil changed recently, the air filter, it's remapped by a reputable company to 150Bhp, I cleaned the MAF (Well, it wasn't dirty to begin with). So I'm not sure what the story is. Should I have better economy, or is there any other parts I can investigate/swap?

Frank Incensed · 12th August 2010, 06:52

Quote:

Originally Posted by ned78

CDT Auto Tourer is giving me a paltry 29mpg on a good week. Should I have better economy, or is there any other parts I can investigate/swap?

Hi

Suggest you start by checking the engine temperature using the onboard diagnostics. Check out this thread thats currently running.

http://www.the75andztclub.co.uk/foru...ad.php?t=66358

Not relevant to high fuel consumption, but don't forget to check your plenum drains, and your PCV. There's lots of info on all these subjects but if searching for something specific Google is better than the search button at the top of the page.

Happy motoring.

ned78 · 9th September 2010, 17:22

Finally got around to doing some checking today, and got to plug my 75 into a Launch. Coolant temp was 91.76, inlet temp 60.66, airflow 476.00 mg/stroke, (At tickover) airflow sensor voltage 2.1v, so as far as I can tell, they all seem okay.

I did find a glow plug relay fault stored into the car, which indicates a glow plug may be shot. Do the glow plugs run constantly on the 75? I know on modern diesels they tend to, which improves the efficiency of the burn cycle. I'm thinking if I have one or more which are MIA, it may be causing poor efficiency.

djw40 · 9th September 2010, 17:31

Is it mainly town driving?

If so, given the load, probably about right.....

ned78 · 9th September 2010, 17:34

It'd be a combined cycle, never really stick in stop start city traffic TBH. I've driven plenty of 320d's in my former job and the mpg was superb, I just find the <30mpg hard to swallow, especially when I hear of 75's here returning nearly 50! My JCW Cooper S can do 30mpg, and that's with uprated injectors, uprated supercharger, and oodles of power. Surely a nice diesel lump should be more frugal?

rossocorsa · 9th September 2010, 17:56

Quote:

Originally Posted by ned78

especially when I hear of 75's here returning nearly 50!

I think there's some optimistic thinking amongst some owners!! the auto is heavy on fuel in urban areas as it seems to hold too low a gear a lot, well at least lower than i would choose in a manual, having said that we get 35 out of ours on mixed runs with a dodgy stat (82 C max) and 40 on a run so something is amiss as when I can be bothered to do the stat I'm expecting a nice jump in economy. I think that in general CDTi auto gives 5 to 7 mpg less than manual

ned78 · 9th September 2010, 17:57

Quote:

Originally Posted by ned78

I did find a glow plug relay fault stored into the car, which indicates a glow plug may be shot. Do the glow plugs run constantly on the 75?

Thanks for the replies guys. Could someone comment on the above if they've experience/knowledge of the M47 engine?

James.uk · 9th September 2010, 17:58

The kind of terrain you drive in makes a big difference..

As does the way you drive.. "Loads of wellie" costs a lot!

If you don't get into top gear (5th) much then your MPG wont be up to much either..

Long, med speed Mway journeys give the best MPG returns..

...

HarryM1BYT · 9th September 2010, 19:34

Quote:

Originally Posted by ned78

As the subject says, my lovely 02 CDT Auto Tourer is giving me a paltry 29mpg on a good week. Now I do carry a lot of weight, I'd estimate somewhere around 100 kilos in the car permenantly due to my SMART repair business being run out of it. But should it be that poor?

I had the oil changed recently, the air filter, it's remapped by a reputable company to 150Bhp, I cleaned the MAF (Well, it wasn't dirty to begin with). So I'm not sure what the story is. Should I have better economy, or is there any other parts I can investigate/swap?

29mpg is quite a lot worse than I got whilst towing a 1250Kg caravan, before I started my efforts to sort the engine out - a manual GB BTW. It was beating 40mpg solo since sorting out the EGR + MAF + PCV it started doing better than 45mpg, which I hope to better since having a new stat fitted.

Matt1960 · 10th September 2010, 07:51

Just under 33mpg for mixed driving for me. I think its the auto which knocks the efficiency of the engine.
Matt

11th August 2010, 23:07	#1
ned78 Regular poster Rover 75 Cdt Tourer & JCW MINI Cooper S Join Date: Jun 2009 Location: Cork, Ireland. Posts: 55 Thanks: 0 Thanked 0 Times in 0 Posts	02 CDT Auto giving 29 mpg As the subject says, my lovely 02 CDT Auto Tourer is giving me a paltry 29mpg on a good week. Now I do carry a lot of weight, I'd estimate somewhere around 100 kilos in the car permenantly due to my SMART repair business being run out of it. But should it be that poor? I had the oil changed recently, the air filter, it's remapped by a reputable company to 150Bhp, I cleaned the MAF (Well, it wasn't dirty to begin with). So I'm not sure what the story is. Should I have better economy, or is there any other parts I can investigate/swap? __________________ http://miniclub.ie/forum/sigs-and-av...nsignature.jpg

9th September 2010, 17:22	#3
ned78 Regular poster Rover 75 Cdt Tourer & JCW MINI Cooper S Join Date: Jun 2009 Location: Cork, Ireland. Posts: 55 Thanks: 0 Thanked 0 Times in 0 Posts	Finally got around to doing some checking today, and got to plug my 75 into a Launch. Coolant temp was 91.76, inlet temp 60.66, airflow 476.00 mg/stroke, (At tickover) airflow sensor voltage 2.1v, so as far as I can tell, they all seem okay. I did find a glow plug relay fault stored into the car, which indicates a glow plug may be shot. Do the glow plugs run constantly on the 75? I know on modern diesels they tend to, which improves the efficiency of the burn cycle. I'm thinking if I have one or more which are MIA, it may be causing poor efficiency. __________________ http://miniclub.ie/forum/sigs-and-av...nsignature.jpg

9th September 2010, 17:31	#4
djw40 Gets stuck in Ford Kuga Join Date: Mar 2010 Location: Tatworth, Somerset Posts: 734 Thanks: 1 Thanked 2 Times in 2 Posts	Is it mainly town driving? If so, given the load, probably about right..... __________________ Ex 75 tourer owner

9th September 2010, 17:34	#5
ned78 Regular poster Rover 75 Cdt Tourer & JCW MINI Cooper S Join Date: Jun 2009 Location: Cork, Ireland. Posts: 55 Thanks: 0 Thanked 0 Times in 0 Posts	It'd be a combined cycle, never really stick in stop start city traffic TBH. I've driven plenty of 320d's in my former job and the mpg was superb, I just find the <30mpg hard to swallow, especially when I hear of 75's here returning nearly 50! My JCW Cooper S can do 30mpg, and that's with uprated injectors, uprated supercharger, and oodles of power. Surely a nice diesel lump should be more frugal? __________________ http://miniclub.ie/forum/sigs-and-av...nsignature.jpg

9th September 2010, 17:58	#8
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	The kind of terrain you drive in makes a big difference.. As does the way you drive.. "Loads of wellie" costs a lot! If you don't get into top gear (5th) much then your MPG wont be up to much either.. Long, med speed Mway journeys give the best MPG returns.. ...

10th September 2010, 07:51	#10
Matt1960 Gets stuck in Rover 75 Connoisseur SE CDT Tourer Join Date: Sep 2009 Location: Herne Bay Posts: 654 Thanks: 1 Thanked 4 Times in 4 Posts	Just under 33mpg for mixed driving for me. I think its the auto which knocks the efficiency of the engine. Matt