(horrendous) fuel economy!

Hi everyone,
just bought a 98 2.5dt auto, totally standard & love it except for one thing... fuel economy!

just serviced it(filters were black!) & while underneath checked for any fuel leaks, ect but hasnt really made a great deal of difference & was wondering if anyone had come across this problem before.

had a couple of auto discos before & i know theyre not exactly economical but this things horrendous... im talking about 30 mile from 20 pounds.

thanks in advance,
Steve

Looking at your figures.....

£20 / £1.41 per litre = 14.18 litres

14.18 / 4.54 = 3.12 gallons

30 / 3.12 = 9.6mpg

that is shocking.....

I don't drive enthusiastically (unless needed to get out of a situation) nor do I 'Drive Miss Daisy' and I average 26.4mpg from my '99 DSE.....

I do about 260 miles a week and use almost exactly half a tank to do that, I guesstimate around the 450-500 mile mark from a tank full.

I would first check the Leak Off pipes on the injectors as these can leak quite a surprising amount of Diesel (although to get 9mpg...thats one heck of a leak) which at times might not be seen as it will burn off on the side of a hot engine.

They are slow, so a heavy right foot will drink fuel like crazy if you are trying to eek more performance from it to get a pace on.....

What mileage do you have?

Mileage is around 145,000, engine starts first time, every time, no excessive smoke ect...

im off work friday so will check the leak off pipes then but its got me baffled!

just got rid of an old bmw b10 v8 alpina which was better on fuel!

Has it had anyone remap it.
Has previous owner had it tuned for pure power and not economy?
I would start with a engine diagnostic to look at first
Good luck
My 1998 p38 manul was good on fuel.

rizlaman said:

Mileage is around 145,000, engine starts first time, every time, no excessive smoke ect...

im off work friday so will check the leak off pipes then but its got me baffled!

just got rid of an old bmw b10 v8 alpina which was better on fuel!

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If it's got 145,000 miles on it injectors will be tired that's for sure. You should be able to get injectors serviced for around £200.00. That would definatly give it a lift. Clean out intercooler first job and EGR valve. Yours should have one. New air filter but i think you already did this.

No EGR valve on a 98 I think? 9.6mpg sounds like a fuel leak to me although there have been reports of poor fuel consumption with a duff in tank pump. I average 24/25mpg round and about and up to 30mpg on the autoroute, year 2000 auto.

Datatek said:

No EGR valve on a 98 I think? 9.6mpg sounds like a fuel leak to me although there have been reports of poor fuel consumption with a duff in tank pump. I average 24/25mpg round and about and up to 30mpg on the autoroute, year 2000 auto.

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Should be EGR Keith. Up to 98 no EGR. 98 and on should be fitted.

Mine is a 97 reg with 148k auto and I avg 17mpg round town and 25 on a run and it has a brand new fuel pump on it I get approx 300miles to a tank full tank cost me £100 have done leak of pipes etc 9mpg does sound bad and it hurts the wallet too

Thanks for all the quick replies guys.
Pretty sure it hasnt been remapped as the previous owner said it was standard & certainly doesnt feel as if its been tuned!
Just bought a FORTE diesel treatment/ cleaner on the way home from work so gonna stick that in tomorrow.
Not sure whether an egr valve is fitted or not but i,ll have a look friday while im checking it out.
Know on my last Disco i blanked it off & seemed to make a noticeable difference.

Check the fuel injector pump - its at the top/front of the engine, easy to see. They quite often leak and are quite pricey to repair/replace - circa £700. Check this thread for details of a P38 I nearly bought with this problem, there's pics and a video in there somewhere too: http://www.landyzone.co.uk/lz/f10/p38-dse-leaking-diesel-hevac-fault-158744.html

rizlaman said:

Thanks for all the quick replies guys.
Pretty sure it hasnt been remapped as the previous owner said it was standard & certainly doesnt feel as if its been tuned!
Just bought a FORTE diesel treatment/ cleaner on the way home from work so gonna stick that in tomorrow.
Not sure whether an egr valve is fitted or not but i,ll have a look friday while im checking it out.
Know on my last Disco i blanked it off & seemed to make a noticeable difference.

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EGR valves get badly choked and restrict air flow also it maybe stuck open. Should have one. Clean the intercooler.

I seem to be averaging 19/20 mpg (£30 = 90 miles) and would love to get 24/25 mpg like datatek. My 2000 DHSE has 117k and I'm about to check my leak off pipes again, starting these cold mornings is a pig (4 tries this morning). Don't know how long they last but I've already replaced once since owning, done 30k+

lenb

lenb said:

I seem to be averaging 19/20 mpg (£30 = 90 miles) and would love to get 24/25 mpg like datatek. My 2000 DHSE has 117k and I'm about to check my leak off pipes again, starting these cold mornings is a pig (4 tries this morning). Don't know how long they last but I've already replaced once since owning, done 30k+

lenb

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Cold start problems is usually glowplugs. Cheap ones don't last
Low cranking speed can also cause cold starting problems.

Datatek said:

Cold start problems is usually glowplugs. Cheap ones don't last
Low cranking speed can also cause cold starting problems.

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Cranking speed is fine
Glowplugs never been changed in the time I've owned it. Will check with previous owner (friend) if he had them changed and when. I know he would have bought good ones. I have only had this over the last few nights when it has beed particularly cold. Starting at any other time after initial early morning start is no problem throughout the day.

lenb

lenb said:

I seem to be averaging 19/20 mpg (£30 = 90 miles) and would love to get 24/25 mpg like datatek. My 2000 DHSE has 117k and I'm about to check my leak off pipes again, starting these cold mornings is a pig (4 tries this morning). Don't know how long they last but I've already replaced once since owning, done 30k+

lenb

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It depends where you live, how it's driven. If you only do short trips, around a busy hilly town in stop start traffic you will be lucky to see 17 MPG. If i drove from here to Blackpool every day i would be getting 22 to 24 MPG. On a motorway at a steady 70 say from here to Manchester airport i would get 28 to 30 MPG. Around Preston tootling around in stop start traffic it drinks the bloody stuff. Mine is chipped and will fly off the mark if asked to, but it's an expensive hobby using the power.

wammers said:

It depends where you live, how it's driven. If you only do short trips, around a busy hilly town in stop start traffic you will be lucky to see 17 MPG. If i drove from here to Blackpool every day i would be getting 22 to 24 MPG. On a motorway at a steady 70 say from here to Manchester airport i would get 28 to 30 MPG. Around Preston tootling around in stop start traffic it drinks the bloody stuff. Mine is chipped and will fly off the mark if asked to, but it's an expensive hobby using the power.

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Must admit most of my journeys are pretty short on average, perhaps doing one 20 mile 'trip' each week (and that includes going through town. Not particularly hilly around here (and not flat either) and I drive 'sensibly' (whatever that really means .... not too fast and not too slow )
I have had a chip on and must admit would use the extra power too often.

lenb

Mikev8,
just read through your threads & watched the vid & i really hope its not the injection pump!
looking forward to spending friday checking it out & hopefully finding something(simple!) as i really like the car.

also see youre a fan of the gsxr 750 like myself!

rizlaman said:

Mikev8,
just read through your threads & watched the vid & i really hope its not the injection pump!
looking forward to spending friday checking it out & hopefully finding something(simple!) as i really like the car.

also see youre a fan of the gsxr 750 like myself!

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I don't wanna scare you, but it's a possibility! It would need to be a fairly major leak from this area to explain the fuel economy, but you need to check everything I guess, and it's a relatively common fault as I understand.

Love my GSXR, best bike I've ever owned U got one too?

Yep, off topic i know but ive got a 2004 K3 750 in rizla colours, hence the name haha, & a 1990 gsxr1100 streetfighter