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28mpg from a TD4 - what's wrong with it then?


FridgeFreezer

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Having got the TD4 freebie sorted and on the road, and even replaced the faulty MAF sensor, imagine my delight when the fuel light came on at only 360 miles on a tank and Mr Esso robbed me of £75. <_< By my calculation this is well under 30mpg, which by all accounts it should manage happily no matter how much you thrash it.

I've had a google and the common faults seem to be not quite right - it starts fine hot or cold, idles fine, doesn't smoke (not that I can notice from the driver's seat anyway), doesn't seem to be leaking anything (oil, water, or air) pulls OK, and as I said I've changed the airflow meter and seen a vast improvement in performance, just no improvement in MPG :(

It had a full service in December including the PCV filter. I changed the coolant elbow the other day which necessitated removing the inlet manifold, which all seemed to be in order although there was a reasonable amount of oily residue in it, it's no worse than any other engine and certainly no worse than the photos on the MGRover forums.

Can anyone shed any light on it, 'cos at this rate I'd be better off getting my old 1800 back and saving 5p a litre!

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Having got the TD4 freebie sorted and on the road, and even replaced the faulty MAF sensor, imagine my delight when the fuel light came on at only 360 miles on a tank and Mr Esso robbed me of £75. <_< By my calculation this is well under 30mpg, which by all accounts it should manage happily no matter how much you thrash it.

In my experience, this is a myth. Whilst it is possible to get some pretty impressive consumption figures from the TD4, driving style and driving conditions play a huge part in determining the mpg.

I've been keeping detailed fuel records for mine since I bought it 2 1/2 years ago. Over 16.5k miles the average stands at 28.9mpg with a high of 33.8 (ironically when my wife drove it for a few days) and a low of 24.0. It's now covered about 82k miles, has a full service history and is well maintained, but I know that my particular usage involving lots of short 1.5-3 mile journeys just doesn't lend itself to good fuel economy. On the odd occasions when I do longer journeys then the mpg increases but conversely, lots of cold starts in the winter and the mpg nose-dives. Mine isn't fitted with a FBH, by the way.

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Darren - thanks for that, does seem quite low though given the handbook quotes 35mpg urban / 42mpg extra-urban / 37 average, and most other owners seem to back up the ~35mpg / ~400miles on a tank figure.

Maybe both of ours have the same fault :lol:

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Well having changed the coolant elbow (it was weeping) & inlet manifold seals (part of the job) and done another tankfull, including a 250 mile run, it's managed ~31mpg now, so I'm maintaining a happy illusion that it'll continue to improve to "normal" levels with a bit more running. The car had been sat for a while, purchased as scrap, put on the road & run with a faulty airflow meter for a bit so it may just need to clear its throat now it's been given some love.

I may treat it to some redex.

EGR valve I'll take a gander at if it doesn't get better as this seems like an easy one to bypass.

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  • 2 weeks later...
  • 2 weeks later...

It seems the crazy fuel economy has hit once again.

2001 TD4 auto, originally full tank = 361 miles all motorway @ 70 bar 20miles on the country lanes. Not really happy

so EGR blanked off and air intake manifold off cleaned and new seals, can of redex and air cleaner throught it an a plug and play fuel rail chip and it went straight up to 450miles plus?

NOW down to 320 miles with the last tank? any other possibilities other than a box of matches or change the car?

Nath

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Two popular possibilities: airflow meter (about £40, unplug it see if it gets better) and turbo control solenoid (about £40, unplug it see if it gets worse) or its associated feed pipes & little filter (a £1 inline fuel filter used to stop crud being sucked in).

There's been a thread on the solenoid very recently wiv pictures and everything.

Mine seems OK-ish now, I've just replaced & re-attached the VCU so waiting to see how it all comes out after a long run.

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  • 2 weeks later...

Well a bit of digging today and I found a pinprick hole in the vacuum pipe to the turbo solenoid - tricky to spot but undoubtedly unhelpful. Replaced with 6mm nylon pipe and it seems to go a bit better now on a brief test-drive round the block, so I guess we'll see how that pans out MPG wise on the next tankfull.

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  • 4 weeks later...

Nath - no idea, sorry, I just got a good 2nd hand one from Boxer salvage. Try the part numbers forum ;) (Also - MAF is the airflow meter)

Having replaced the vacuum pipe to the turbo solenoid, changed the filter & lubricated the actuator rod, and run a bottle of Redex through it, it seems much better, MPG improved a bit and it got smoother & nippier.

On the last tank I've experimented with keeping it below 80 and it's just ticked over the 400 miles mark at long last. Now it's proved it can do it if it tries, I'm tempted to get it chipped to remove the official-mpg-figure-friendly zones from the fuel map so I don't have to drive like a granny.

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I get round about 30mpg from my 2005 TD4 auto and this is mostly journeys of no more than 5 miles and no M/way journeys (about 70 miles to nearest M/way). Fitted the EGR bypass and new crankcase filter also new rear shoes and drums as handbrake was sticking on. Used to get 25mpg on previous 200tdi Discovery and 14mpg on earlier V8 Range Rover so consider the mpg I get now far better than previous Land Rovers.

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On the 320d BMWs (same basic engine) the biggest improvements in mpg seem to relate to getting the coolant temperature up. Make sure the thermostat is working correctly in the 90plus degrees range. Not sure if the Freebie has on e but there is an 2nd thermostat on the beemer engine which can also fail leading to poor mpg. Think it is part of the EGR valve assembly. Might be worth checking?

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OK - So I have a manual TD4 (2002) not an auto, but I find that there is a HUGE difference in fuel economy on long journeys depending on how fast you go.

I consistently get 40mpg if I try to sit as much as possible on 70mph (75 on the clock). If I push it to 75-80 then the MPG goes down drastically.

I have no bypass or chipping - just try to keep everything clean and well serviced with correct fluids.

See you in the slow lane!

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