Sudden MPG loss on Dual Carriageway

**skip85** · 14th November 2010, 08:57

Hi All,

Need a little help to figure out a problem!!

I had my car serviced 2 days ago. With this the MPG had become less than what it had used to (53mpg ave down to 47mpg) and not get any better. It had the EGR cleaned, fuel filter replaced and fuel conditioned added. This had then led the MPG to rise back to 53mpg ave on my journeys to work so was happy as larry with that.

Driving home last night i was cruising at 65mph on cruise control and ave trip was saying 53.1 then all of a sudden MPG dropped to 43 on Dual Carrigeway and dropped to 40 by time got home. No loss of power and boosted fine with no smoke coming out of the back, just that it was apparantley drinking diesel quicker than i can drink beer!!!

Went out agin in it last night and ave mpg rose to 43 on a light run round and up to 45 on run to work!!

Anyone have anyideas as very concerned!!!

Thanks

**cont1204** · 14th November 2010, 09:22

What engine model/year is it? And is your car an automatic or manual, hatchback or estate?

I know that's a lot of questions but it will help to work out if the car has a DPF or not. If it does they tend to drink diesel when it's doing a re-gen. Did you have any lights on on the dashboard?

**skip85** · 14th November 2010, 10:21

Its a 2006 1.9cdti 150bhp estate, manual. No lights on dash and never seen it drop before like this in 10months of ownership

**vectraboyy** · 14th November 2010, 10:22

Estate has DPF from what i remember so it was probably that.
It doesn't happen regulalry thats why you may never hae noticed it before.

**skip85** · 14th November 2010, 10:26

Originally Posted by vectraboyy

Estate has DPF from what i remember so it was probably that.
It doesn't happen regulalry thats why you may never hae noticed it before.

Being slightly new to Vectra tech speak what is DPF?

**vectraboyy** · 14th November 2010, 10:31

Diesel Particulate Filter.

From what i know...

It stores some of the crap in a box in the exhaust and then does a regen whereby it burns it off, will smoke a bit more and uses more fuel from what i understand of it.

Id wait for someone to confirm or deny this though!

**skip85** · 14th November 2010, 10:36

Originally Posted by vectraboyy

Diesel Particulate Filter.

From what i know...

It stores some of the crap in a box in the exhaust and then does a regen whereby it burns it off, will smoke a bit more and uses more fuel from what i understand of it.

Id wait for someone to confirm or deny this though!

Will do? Any other ideas?

**bafoo** · 14th November 2010, 18:30

Sounds like a re-gen to me too, Mine did one last week, did 30 mpg for a good 20 minutes, with plenty of smoke too!! You could, if you have access to op-com or similar, look at the distance since last re-gen and see if it tallys roughly with the reading of your odometer.

**skip85** · 14th November 2010, 18:36

Originally Posted by bafoo

Sounds like a re-gen to me too, Mine did one last week, did 30 mpg for a good 20 minutes, with plenty of smoke too!! You could, if you have access to op-com or similar, look at the distance since last re-gen and see if it tallys roughly with the reading of your odometer.

I can't access it so what is best? Leave it and hope it improves or take it back to garage
!?

**Big Sig** · 14th November 2010, 18:40

If it was on a regen it will stop it as soon as you turn the key off. One way to tell is stop, and whilst its ticking over check the inst mpg on the fuel comp. If its showing a much higher reading than normal 1gph etc then its on a regen. Its always best to let it finish its cycle too.

Do a bit of reading on diesel particulate filters too