Picasso - poor fuel consumption

vax2002

There is no "magic duster" that service garages use that if you miss your car breaks, they are parts that are replaced routinely at set mileages like fuel filters.
I am amazed at the comments some come up with about a service been overdue causing immediate failure.
Now a genuine cause could be a gunged up EGR valve, get the garage to strip it off, clean the tar out and re-fit it.
The MPG will return.
Incidental this is not a service item, but is a major cause of poor economy on french diesel vehicles.
Had exactly the same problem on a Renault 1.9 td, cleaned the EGR and feed pipes , it was solid with gung and mpg went up from 28 to 44 immediately.

Norman_Castle

The last week the car has struggled to start - have to keep the key turned until it ticks over and starts.

When starting do you wait for the pre heat light to go out?

tvaustin

No preheat light is lit when I try to start the car.

Just done a manual fuel consumption. I filled up with £20 when my warning light came on and reset my odometer. warning light came on last night and I had done 100 miles just driving to work, city etc.

According to my calculations this equals MPG of 31. Trip computer showing 30.4

LandyAndy

tvaustin wrote: »

No preheat light is lit when I try to start the car.

Just done a manual fuel consumption. I filled up with £20 when my warning light came on and reset my odometer. warning light came on last night and I had done 100 miles just driving to work, city etc.

According to my calculations this equals MPG of 31. Trip computer showing 30.4

That isn't the way to do an accurate manual consumption measure.

tvaustin

just a quick update

I took the car to the garage (was showing fuel comsumption as 29 MPG before I took it in). I mentioned about the EGR valve. He connected it to the diagnostic machine and it came up with no faults - he said if the EGR valve was stuck then this would show up as a fault.

He couldnt see anything else wrong with it but did put some injector fluid cleaner in and gave it a service.

He did say that if I was to take it on a 100 mile trip then my fuel consumption will go up but what I dont understand is that when I purchased the car I was doing 39 MPG and was doing the same trips i.e. urban driving and then all of a sudden my fuel consumption dropped to around 35 and then below 30 and yet nothing is wrong?

I have to pick the car up tomorrow so will see if a service has improved my fuel consumption

grizzly1911

We used to have a Picasso HDi, did 80k from new. i had only had the older 2 stage combustion diesels before. Those old diesels would do constant MPG whether stuck in traffic or being flogged up the motorway.

I have since had four high pressure diesels, like the Citroen and the fuel consumption varies much more depending on where/how driven. they can be very good or just good.

Our Picasso used to do 50ish on open roads/motorways but would drop to low 40s around town (we are semi rural). The Avensis we have now varies between 54 to 47.

A PP has mentioned the winter diesel issue and I also notice a drop in fuel consumption from around November, colder starts and cooler running probably don't help on short journeys either.

Don't believe the computer and check consumption over whole tankfuls, brim to brim.

Did they check you brakes weren't binding during the service?

Are all the tyres correctly inflated?

Doubt the electrics would make any difference to fuel onsumption.

tvaustin

another update:

When i picked the car up from the service the warning light came on on the way home. I filled the tank up to brim which was 51.78 litres and reset my trip computer
The following day I went on a 100 mile round trip and the MPG was showing at a peak of 48.9 so was really happy.

Since then I have just driven the car in urban conditions and obviously the MPG has dropped steadily.

The low diesel light came on today and I have done 412 miles since I last filled up and according to my calculations this means 36.17MPG (trip computer showing 34.9) still not what I was expecting though.

I am still having problems with the car starting though as this morning I had to keep the key turned for a good 10 seconds before it ticked over. I have never seen the pre heat light on my dashboard and I am leaving key in ignition about 10 seconds before I try starting the car. Normally this problem occurs first or last thing at night and is usually fine during the day

mattyprice4004

To get an MPG figure that means anything, you now need to brim the tank and then work out how many litres it's taken you to get those 412 miles.

It could be a good 5-10 litres each way if you go by the gauge, which could equal a 10mpg difference!

vax2002

The EGV valve would only show a fault if it had an electrical problem, if it is gunged up as is very common, it wont show any lights.
My advice is find a real mechanic who does not think the code reader is all he needs, ask one to take the egrv off and have a look, a 15 min job.

forgotmyname

The previous owner either did more economical journey's than you
of drove more economically.

Are you making the most of the engine and gearbox, Changing up too soon
can use as much fuel as changing up too late.

Best MPG is usually around the peak torque figure in the rev range. Unless it has sufficient
torque to pull the car along without using extra throttle.