E300 td mpg - help!!

[colin.dillon]

The fuel consumption of this car is driving me mad! I've never got over 320 per tankful. I've just worked it out over the last tank & it averaged 23.1 mpg - this was with a motorway trip of 120 miles & keeping the speed down!! to 80 with no traffic. The balance was done by wife doing a 10 mile return trip to work while her car was off the road. (No - she isn't a 'boy racer' in drag!!)

It's been serviced, had injector cleaner, wheels tracked, tyre pressures checked - what more can I do??

There's no lack of performance - goes like a rocket!!

It's an '98 auto estate - surely I should get better consumption than this.

Oh - it's also had the auto fluid changed!

Any help appreciated!!

Col

 

[DrNick]

I've been looking at mine recently. I used to get 33-34mpg on the motorway, but over the last few tanks its fallen to 30-31 same driving. This is since I've fitted the new MAF and run a few doses of injector cleaner through it. I was hoping things would get better, not worse. Note my mileage is 90% done on the motorway on cruise control so its a pretty well controlled experiment!

I have noticed in the past that the state of the air filter makes a big difference and mine is due for a new one now so I'll have to see if that makes a difference. Worth having a look at yours even if it has been serviced. 2 minute job to have a look at it!

I'd be interested to hear if you manage to improve things

 

[colin.dillon]

I've been looking at mine recently. I used to get 33-34mpg on the motorway, but over the last few tanks its fallen to 30-31 same driving. This is since I've fitted the new MAF and run a few doses of injector cleaner through it. I was hoping things would get better, not worse. Note my mileage is 90% done on the motorway on cruise control so its a pretty well controlled experiment!

I have noticed in the past that the state of the air filter makes a big difference and mine is due for a new one now so I'll have to see if that makes a difference. Worth having a look at yours even if it has been serviced. 2 minute job to have a look at it!

I'd be interested to hear if you manage to improve things

I forgot to mention that I changed the air filter after the service just to be sure!! - didn't make any difference!

I was thinking of changing the MAF but I'm now having second thoughts.

Can't think of anything else to do apart from maybe having the injectors removed & tested - I do need to book it in to have new glow plugs so I'll ask for them to be checked @ the same time.

Col

 

[mark.t]

34.1 on mine .................i do use millers diesel power plus on every fuel up...

 

[colin.dillon]

34.1 on mine .................i do use millers diesel power plus on every fuel up...

I'd be happy with 34 - is this town driving or motorway?

Col

 

[mark.t]

mpg

combined 24mile round trip motorway.....3 mile either end road work....

 

[R Phillips]

Thats about the same as mine has done for the last 70,000 miles.
On a trip with lots of motorway miles it may do 400 on a full to
empty tankfull.

 

[colin.dillon]

Thats about the same as mine has done for the last 70,000 miles.
On a trip with lots of motorway miles it may do 400 on a full to
empty tankfull.

You're all making me jealous!!!

Col

 

[230K]

Hi

Best i have got is 570 miles to the tank and i was cutting it fine, usually 500 until light comes on. I always like to see 100 mile on the odometer before the guage reaches the bottom of the fullmark.
192000 miles 90% dual carraigeway work, i have found the secret for good economy is keep tyres pumped 32 front, 36 rear, change air filter every 10K( i find a new one makes ~3mpg difference when changed), fully synthetic oil Mobil1 or similar, keep below 70 and do not use the turbo boost unless you need it.
I go between bouts of good economy and poor economy depending on how i feel and note every drop of fuel put in. Averaged 35 over 5000miles. Strong acceleration eats fuel remember the 300TD estate with a full fuel tank and driver is not far off 2 Tonnes.
Colin i have been thinking a lot as to why your economy is so poor and i really am stumped, could there be a tuning chip fitted?

Hope you find some increase.

230K

 

[230K]

Hi again

I have also found that W/S makes very little diff to economy

230K

 

[mark.t]

counting

try counting through the gears..... to make sure your not hanging in third when you should be in 4 and so on .....any leaking fuel.....is it over fueling plenty of black out the rear pipe......hpoe you get it sorted

 

[colin.dillon]

Maf

I've disconnected the maf - it seems to make little difference to performance - just seems a little slower @ low revs - does anyone know if this is normal?

Thanks

Col

Mark.t - it does all the gears perfectly.

230K - you've mentioned something that I've had @ the back of my mind re tuning chip but how would I check? I realise that I'm now clutching @ straws!!

Col

 

[230K]

Hi again

Have you tried to see if the cat has become partially blocked, have read on here somewhere of someone testing the pressure differential across the cat although when you say that the car still goes well it is unlikly thast there is any serious restriction in the cat or exhaust.
The turbo 606 really fills the inlet manifold with gunk, although when i cleaned mine out if any it worsened economy very slightly.
I also tested the MAS sensor with a volt meter and it is very simply done which would be another thing eliminated.

I might be going over old ground but i do hope your economy improves.

230K

Another thought do you use the same filling station all the time is it possible that you are getting short measures? (clutching at straws now)

 

[230K]

Colin

I hadn't seen you last post before i posted mine,

Do not know where you would look to see if the car has been chipped, Jimmy or Dieselman might give you some idea where to look.

Try your next fill and drive it like a snail, do not exceed 2000rpm even when accelerating which equates to about 60mph in fifth and see if you get it into the low 30's.
From a brimmed tank i like to get 100 by the bottom of the full mark, 200 by 3/4 and 330 by the time it slips below half.
Thinking back mine did 30 even on a 2400 mile trip to France with six on board and a roof box cruising between 70 and 80 even if i did manage to run out of diesel at one point.

230K

 

[jimmy]

The most obvious place for a 'piggy-back' type tuning box would be in the ECU box, there is plenty of room in there, or trace the wire harness from the fuel injection pump to see if a box has been tapped into it. If it has been chip tuned you have no way of telling.

If you see obvious, thick, black smoke in the mirror when flooring it then it probably has a tuning box, chip tuning does not or should not make it smoke if done properly.

I had similar concerns with mine, checked everything, had the injectors checked, changed all the seals on the fuel lines but was still the same. I can only but it down to my driving!! When we go away on holiday, long trips and having to drive sensibly sees the mgp shoot right up, local driving on my own is not so good for economy.

Chip tuning has increased mpg considerably, I would imagine!!

 

[sym]

Keeping to 70mph definitely makes a big difference on mine .... Still struggle to get below 30mpg with the diesel, even when in a bit of a hurry, but the results when I drive carefully are impressive.

I'm also considering a Tuning chip, for the reasons mentioned above .... anything that increases mpg and power has to be a good thing

S.

 

[Dieselman]

As mentioned before make sure the car is going into 5th and not holding 4th. The stick needs to be at the left of the gate marked "D" not the right marked "4".
You should check the speed to revs is 29mph / 1000revs.

In general if a diesel doesn't smoke there is nothing wrong with the combustion or injectors.

Things to check:
Air in fuel lines, MAF, EGR valve, filter, cat, injection timing, injectors, engine compression, boost and gearbox lock up clutch.


Tuning chips often improve economy as they produce more torque so the gearbox selects a higher gear sooner.

If all these are ok then just accelerate more slowly and watch the fuel economy. Try accellerating so the box changes up at 1500-1700 revs and see if you still keep up with traffic ok.

A couple of tanks ago I only got 25mpg but this was all short journeys and a few good burnouts,the car had stood for six weeks and I was very bored. Now economy is back to normal, approx 33mpg.

 

[colin.dillon]

Mpg

230K - re short measures I've even got to the stage of using the same pump @ Asda & filling it brim to brim to check the mpg!!

Jimmy - Is the ECU in the driver's footwell?

Col

 

[Dieselman]

Jimmy - Is the ECU in the driver's footwell?

Col

Under the cover N/S of engine bay in the scuttle.

 

[colin.dillon]

Under the cover N/S of engine bay in the scuttle.

Thanks for quick reply!! I'll check tomorrow morning.

Col