poor fuel consumption

[defender1010]

Hi i have a 02 406 hdi lx estate (110hp) only 90k on the clock, the fuel consumption is really poor showing an average of 35-36 mpg, i also keep a fuel diary and the manual calculations match is their any reason why it is so heavy on fuel .
I have checked the following
1 breaks (their fine)
2 removed the EGR and test (it was fine)
3 Tyres (all the same and same pressures)
4 fitted new MAS (no improvement)
5 No faults showing up on a (snapon code reader)
do i just have a bad peugeot help needed

[gumby6371]

Hi and welcome,

What sort of driving are you doing, town driving with short journeys are not what those engines are designed for.

Having said that a fuel and filter change along with some injector cleaner should help boost the mpg a bit.

[lozz]

is your, 35-36 mpg return/ off round town driving ?

edit, gumby posted simalar question before me, ignore this one,

[waue1978]

I could say exactly the same about my car. My 110 estate has also only done 90k & my average is slightly lower due to all the short journeys (34), but even on a run I'm only likely to get 40-45 unless I drive like a nun. Filter changes have made no difference to mine & I've just learned to live with the fact that I may not achieve 60mpg. Peugeot's official figures are 37 around town & 64 extra urban (which is steady 55mph) & those are usually achieved in a closed room on a rolling road with a computer controlling the throttle. Town running may not be what the engines are designed for, but over the 7k a year I do it is still a £500 saving over the 25mpg I would get from a 1.8 petrol of a similar size.

[martint]

It'll just be a worn engine-just cos its only done 90k means nothing. I know a mate who had a 110 estate & he only got 43mpg on a run. When he put it in to a guy that rebuilds engines,the cylinders were worn,needed new rings etc. He got it rebuilt & now gets better mpg than mine(55mpg).
All depends on the person who owned it b4 u& whether he used good oil plus servicing it often
Just 1 more thing- have u got semi synth oil in it? I put 5w-40 fully synth in mines & it hated it. Emptied oil out & put in 10-40 semi (comma x-flow) and its crept up from 44 to 49.6 around town with a bit heavy foot & remapped to 120bhp

[Welly]

I used to run my 110 door-to-door, less than 10 miles each way etc.......

Winter = 33mpg

Summer = 37mpg

If I tried *really* hard on a long easy run I'd be able to eek 50mpg out of it.

That's why I went back to petrol in the end because they warm up quicker and are more simple

I believe there are good ones and bad ones out there too. I firmly believe there is a problem with HDi injectors as they get older - a clattery engine would point to the fuelling being a bit off, you'd probably need an injector replacement/refurd for best economy but then you need to think about the pay-back time which'd probably never happen

Tyre pressure should be 2.3bar all round, I remember mine were low once and saw a 3mpg improvement once sorted.

[grasmere59]

My old 110 Rapier did 49-52 on a run and never seemed to drop below 45 on short runs on the other hand my 110 exec i have now won't do anything near that,if i reset the mfd on my usual 120 mile run and take it steady it will show nearly 50 but as soon as the town work starts it drops like a stone.I know the fuel computers are not supposed to be that accurate but they were not that far out on both cars,they've both done similar mileages and have full service historys so i can't make it out,the Rapier even went better and did more mpg! I'm going to get the Exec remapped soon so i'll see if that makes any difference

[pavlf]

I've just bought an 02 110 rapier and it's not getting anything like what i expected. I just drove a 150 mile round trip on the the motorway doing 75-80mph and only got 39mpg! My old 2.1 was better than that, and my old 405 even better. It's heading for having all filters changed I think.

[martint]

If i was only getting 39 id sell the car,what wi the prices of diesel,to come.

[Busman]

I've just done 500 miles over 3 days, mostly motorway and dual carriagewa in my 110 estate. So I thought that i'd use it to check the trip computer. So I filled the tank and reset the trip computer and wrote down the mileage. 500 miles later i filled up. Trip computer said 42.5 average, worked out the traditional way, 48 mpg. I'll fill it again in a few days and do an average of the two. I tend to potter down the motorways at about 70-75. But it creeps up to 80 ocasionaly.

[rwb]

the fuel consumption is really poor showing an average of 35-36 mpg

Not bad if it's all town driving.

i also keep a fuel diary and the manual calculations match

My computer under-estimates by between 9 and 12 mpg compared to brim-to-brim fill calculations.

I put 5w-40 fully synth in mines & it hated it. Emptied oil out & put in 10-40 semi (comma x-flow) and its crept up from 44 to 49.6 around town with a bit heavy foot & remapped to 120bhp

Interesting. I've just had an oil change and I'm sure it feels a bit perkier.

Winter = 33mpg
Summer = 37mpg

Any excuse for me to get my graph out:

I firmly believe there is a problem with HDi injectors as they get older

How old? Age or miles? I'm currently enjoying a bottle of Wynn's Injector Cleaner For Diesel Engines.

150 mile round trip on the the motorway doing 75-80mph and only got 39mpg

That does sound rather poor. But was it steady cruising, or hard accelerating and braking to keep up with angry salesmen in their Audis?
Mine has a sweet spot at about 67 -- but mine's a 90 which has a shorter final drive so that comes up at about 2400rpm. I assume this is where the previous (first) owner put 84,000 miles on it in three years.

[Bailes1992]

Mines likes to cruise between 60-70mph too.
Also has another sweet spot about 95mph but I never go that fast anyway.

After 70mph the fuel economy nose dives like hell! Doing ~50mpg at 70 and 35mpg at 80mph.

Also the car seems totally unsettled at 80mph, seems to sound like it's struggling and drones quite loudly. But anything higher than 85mph and it settles again.

I'm getting around 45mpg and thats very mixed driving. Mainly motorway, some 80mph some 65-70 and some days I just do 60mph. Depends what mood I'm in.

I went back and fore Oxford doing 65-70mph, also with some thrashing around the back roads and 300 miles later I'd done 52mpg so what happy with that.

You just have to consider these engines are getting on and nowhere near as economical as the equivalent modern engines. Back in their day they were great!

[waue1978]

You just have to consider these engines are getting on and nowhere near as economical as the equivalent modern engines. Back in their day they were great!

I wouldn't be too sure of modern engines being that much better. If all you're going on is published figures then they are mostly bull. The brand new Renault Grand Scenic I had last year had the 1.5DCi engine & was quoted in the official figures as doing 48mpg on the urban cycle. I got 45 on the run to Welly which was mostly dual carriageway at no more than 75mph using cruise for a fair bit. The Hyundai i30 I had for my last week had the same size engine & still only managed 48mpg over the course of the week.

Next time you're in a newsagent, pick up a copy of Auto Express or similar & check out the mpg they get out of one of the cars they road test. Then compare them to manufacturers official figures. There's a fair difference between what can be achieved on a rolling road with no headwinds or gradients compared to real life.

[rwb]

According to spritmonitor the best reported BMW 320 'efficient dymanics' gets only 4.36 litres per 100km which is 54MPG (cf. fuelly), so you aint gonna get your money back forking out for one of those over a 406.

I think this pretty much sums up what's happened with 2-litre diesel engines over the last 10 years: twice as much power, but no more efficient.

And as for the small diesel engines: I'm sure they're good in small cars.

[rwb]

Just had a nosey at your spritmonitor page Sam: I notice your computer under-reads by 5 to 7 mpg. It also seems to have the same favourite numbers as mine: 40.9, 47.9,...