C5 2.2 HDi Auto - High fuel consumption?

[Longyear]

Hi all,

I picked up a late 2002 C5 2.2 HDi Auto on Friday past. It was serviced in Jan, has no FAP related error messages (or others), and appears to drive beautifully, without fault . It idles smoothly and pulls cleanly.

Yet despite this, since resetting the average MPG when I got the car, I am only seeing an average 27 mpg. This has come from a mixture of urban and 'extra urban' driving. I know these cars are heavy and with the auto box was not expecting the most economical diesel on the planet, but I'd hoped for late 30s and others seem to achieve this. Today, I had a 60 mile round trip to make, so reset the fuel computer again and took it very easily (65mph on the motorway and smooth, quite slow acceleration). After the trip I checked the computer and I'd only averaged 31.5mpg.

When I bought the car on Friday, it was showing an average of 37mpg, but the last owner did say he "drove like a retired vicar running early".

Can anyone tell me any likely causes for such poor fuel consumption in an otherwise well-running car? ......... Is there something about 'swirl valves' or something (I have no idea what that is!) that can cause high fuel consumption?

Thanks in advance for any pointers!

[steelcityuk]

Hi,

I can't say for sure about your C5 but the C5 I had, 2.0 HDi 110 manual would usually give 35mpg in an urban setting. According to some this isn't unusual. For comparison a XM 2.5 TD manual gave around 32mpg and a XM 2.0 TCT with LPG 18mpg in the same useage.

Steve.

[Lighty]

I would say, get the injectors checked, and get a remap with the fap removed, with al these done, you should get 40 mpg

[vinypeps]

Before you do any of the above do a neck to neck check, top it right up with diesel and reset the trip meter to zero, then run it until it gets to a quarter or below, then fill it right up again at the same garage and pump if at all possible, then check the litres against the miles to give a accurate figure, it could just be a false reading on the computer thats giving the low mpg, I had a 2002 auto 2.2Hdi for 2 years and it averaged about 36 mpg on mixed driving, I did once get 47 mpg out of it on a round trip to Brittany.

[Harlequin]

does it need a service?

[SaabC5]

My 2.2 HDi manual only returns on average 29mpg around Central London, it will go as high as 60mpg on a long motorway run if i drive like a guilty vicar at a constant 60mph. If i drive "normal" motorway speeds 45mpg is quite normal so i would expect the auto to come within 3/4mpg of these figures.

Try some Wynns EGR3 cleaner into the EGR valve/exhaust manifold for starters and then consider other things like an air filter change and even a faulty MAF sensor.

[Longyear]

Thanks for the suggestions guys.

The car was serviced in January, and had a new standard air filter as part of that.

I definitely plan a FAP removal and remap but it's probably about 3 months off at the moment, until funds allow!

I am sure that I should be getting more than an average 29mpg from this car based on what most of you have said.

@ SaabC5 - I've ordered some EGR Cleaner as someone else suggested that too. Can you give any starter advice on where the EGR is located on these cars/engines, and any tips of getting to it and cleaning it?

I already have some electrical contact cleaner in the garage - is it advisable to use this on these cars to attempt MAF cleaning? ... (I know some cars respond well to MAF cleaning, whereas on others, it's not advisable at all).

many thanks.

[Peter.N.]

Going by the previous owners figures that sounds about right for an auto, I drive like him and am only getting around 42 mpg and that's on mostly rural roads, that compares very poorly to my 406 2.0 hdi which does about 10 mpg better.

Peter

[bxzx16v]

They are certainly not that economical the 2.2hdi mine struggled to get over 30 mpg in town , my 2.0 hdi 8v could manage 35 mpg .

Mark

[Monkeyfeet]

Hi,
They're not known for super economy, but my highest, on a m'way / dual carriageway run (120ish miles) was 60mpg. Drops to below 40 around town but normally maintains 42 / 43 mpg and that's over 2000 miles of very mixed driving.
Loves motorways, hates busy towns!

[HaydnR]

I'm having similar problems with my 2.2 manual 32mpg a road short runs 35mpg 400 mile motorway run. E egr cleaner used and manually dismantled and cleaned, Fap removed, injector cleaner used. Lexia not showing any problems.

[Longyear]

Mmm, interesting. Not the most economical diesels in town then eh!

It's my own fault as I should have done my research first. But it is bizarre that my other car, a Skoda Octavia VRS 1.8T petrol, which is remapped to 205bhp, never drops below 34mpg average; so is currently more economical than a HDi diesel. That I would not have expected!

Going to try a MAF clean, and some BG244 and see if there is an improvement.

Cheers.

[SaabC5]

@ SaabC5 - I've ordered some EGR Cleaner as someone else suggested that too. Can you give any starter advice on where the EGR is located on these cars/engines, and any tips of getting to it and cleaning it?



many thanks.

If you remove the front half of the engine cover theres an aluminium pipe that runs out of the exhaust manifold, it goes slightly right and then to the back of the engine bay where it enters the EGR. The pipe is held on at the front by 2x 10mm nuts, just undo them and spray the cleaner down the pipe in short bursts towards the EGR valve. Also spray the opposite way into the gunky manifold, chances are you fill find a real heavy residue of black crud in the pipe going to the EGR. If nothing else you will find the car drives smoother and picks up better afterwards.

[Citroenmad]

Check that the MAF is a genuine unit, cheap ones give poor economy - in my experience!

I know someone with an identical C5 to yours and it is doing the same MPG, its not got a genuine MAF and once it is swapped to one im pretty sure economy will be restored. This C5 did 32MPG on a good long run at 65mph, my two petrol Xantias are far superior ... 27mpg, even around town, it not acceptable for a diesel.

[waynedance]

I'm having similar problems with my 2.2 manual 32mpg a road short runs 35mpg 400 mile motorway run. E egr cleaner used and manually dismantled and cleaned, Fap removed, injector cleaner used. Lexia not showing any problems.

Forte Diesel Treatment work for me, see this post about half way down.

http://www.frenchcarforum.co.uk/forum/v ... =3&t=41206" onclick="window.open(this.href);return false;