Fuel Consumption!

[Norwichmale]

Hi all,im hoping someone may be able to shed some light on my fuel consumption. Im getting around 32.3mpg on a run. I have just done 670 miles over the weekend and a good 650 were motorway and 'A' road miles. I also splashed out £130 in diesel!

Im driving a 51 plate 2.2 auto exclusive.

 

In the past couple of weeks it has had a new oil filter,fuel filter,air filter,one new diesel injector,new intercooler,DPF Regen,new Maf sensor and some of the good old diesel additives.

 

It was all trouble free motoring and drove like a dream with the exception of slow pulling away from a standing start. There are no fault lights on and i must admit i am now at a loss!

 

Any help would be very much apreciated

 

Thanks in advance

 

Jon

[Randombloke]

The early 2.2 is not good on fuel, and the auto box simply heats up the transmission fluid rather than transmitting energy to the road wheels.

 

My first port of call, and the thing that has always made most difference to my 2.2 manual is to free off the front brakes, and to reduce the amount of spring loading in the anti rattle springs to the point where they are just stopping the rattle rather than requiring that the pads be forced into the channels and are then jammed sideways by the overly keen springs.

 

Doing this alone has seen me jump from 38/39 on long runs to 45mpg.

 

My mate with the auto 2.2 never sees more than 40mpg.

 

It should take you about 25 minutes per side. Unless the callipers are binding badly, you should not need the piston winding back tool, but I would have one standing by just in case, and if you every need to change the pads you will need to have one anyway. Don't forget to unplug the pads from the wear sensing cables, and have a couple of small cable ties standing by to secure the longer wear sensing wire when you put it all back.

 

Tell us how you get on.

[paul.h]

2.2 hdi auto official figures in a 2003 brochure are 28/52/40 mpg urban/extra urban/combined.

If not done already, then reset the trip computer by pressing on the end of the wiper stalk and then go on a run in case the figures you have are affected by a lot of previous town driving.

 

As well as checking the brakes are not binding, I find on motorways if you keep to about 65 mph then fuel consumption will be about 10% less than if going 70ish, do not race up the hills and also the weather has a large effect - if into a wind then expect extra 10% fuel used. I do a lot of trips on the M62 between Warrington and Hull and in good conditions can get high 50s mpg but in bad can get 45 mpg. - this is for our 2.2 hdi VTR manual (6 speed) mark 1 hatchback. Also use the instantaneous mpg on the trip computer to see how different driving styles affect mpg.

 

If it is due for a DPF change, it may be blocked up and that has been mentioned on here that it increases fuel consumption.

[mechcanico lee]

You say its a bit sluggish on take off , make sure you have no boost leaks, its worth checking that the egr valve isnt being pulled open when it shouldnt be , this can affect fuel mpg greatly , does the car black smoke at all ??this is signs of either over fueling or underboosting .

 

The egr you can test its on the inlet manifold near the bulkhead , pull the vac pipe off and try another bit of pipe on it , suck on it and realease you should hear a positive clunk as the valve head hits the seat, if it doesnt sound positive egr needs to come off a be cleaned so its free.

You can blank it off, put a ball bearing in the vac pipe and replace pipe .....egr will not open then , see if your mpg gets better then , on later cars you carnt do this as the managment sees egr not operating and puts them in limp , should be ok on an early one though

 

You say you had a regen on the dpf , with diagnostic gear on you need to see what the differential pressure is reading, this is the pressure difference before and after the dpf filter , my pug 607 2.2 hdi reads 0 millibar at idle and 40 millibar at 3000rpm so would say the citroen would be about the same .

 

If the differential pressure is still a bit on the high side the car will try to regen whilst on the road this eats fuel also .

 

My pug at 70 mph does bout 50 mpg its a manual but i wouldnt of thought there would be a great difference between the citroen auto box .

 

Some things to have a go at

 

Hth Lee

[paul.h]

Something else very easy to check.

At the gearbox end of the cylinder head is the swirl actuator - called a diaphragm by Citroen. It looks like a thin rod with a ball and socket connection on the end and the plastic socket often breaks. New cost is about £20 but it is a pig to fit. There are a few posts here on how to do it. When it breaks the acceleration may be down and some have had warnings (anti pollution ?) but in my case I just noticed it was broken but once replaced it did accelerate quicker.

 

Some different fuel supplies have been reported as giving poor economy, Shell is reported as giving good mpg, I tend to use Sainsburys and that gives good mpg and is also the cheapest here.

[Norwichmale]

Hi, and thanks for all your thoughts and replies guys,I have a day off work tomorow so will be looking into my mpg fiasco and will hopefully get it fixed!

I have had another thought which may or may not be of any relevance,but i did replace the crankshaft pulley a week after buying the c5.

Is there anything i could have done wrong when fitting it to cause my sluggishness and low mpg? To be honest when i took it for a test drive i cant remember it being like that otherwise i would have probably walked away from it.

 

Thanks J

[mechcanico lee]

It shouldnt of upset anything the cambelt gear behind it is on a keyway so in theory nothing should have moved.

[paul.h]

If you disturbed the timing belt and the timing is now out it could be giving the symptoms.