406oc.co.uk

Hi there,

My 406 HDI 110 seems to use fuel too much in my experience...i have an identical 406 which seems to be better by miles.
I put £18 quid in yesterday and after about 45 miles the fuel gauge seems to have dropped significantly...and i dont drive it hard. I suspect somethings not as it should be....also seems a bit sluggish compared to the other car.....any ideas what might be amiss guys?

Cheers
Pugface

What's the actual MPG you're getting?

When was the last service?

Anything on the display?

You need to tell us the mpg. Mine does 55 to 57 in general useage as a guide.

Hi,....im getting around 30mpg i reckon

pugface

Town driving I get around 38mpg. Long motorway cruises - anything up to 49mpg. Heavy footed motorway cruise - around 44mpg.

am the same with my car i put £25 in it last friday drove to edinburgh and back to glasgow and it was just on 2 bars tbh i think my fuel pumps at fault as the car is hard to start and it sometimes cuts out when i give it alot of throttle plus it showed up on diagnostics that the fuel pump was at fault

It's almost impossible to assess your mpg by filling up with £18.00 or £25.00 and comparing that to driving X amount of miles/journeys and what the gauge is showing.

You really need to brim the tank (so you can see the fuel resting in the filler neck) drive around for a few days as you would normally and then brim it back up. Divide the amount used in gallons by the miles to give an average mpg.

If you get the diagnostic port hooked up to a code reader you can get the live fuel rail pressure off it. At idle the fuel pressure should be around 298 bar rising to 800+ bar with higher revs.

You should also check if the thermostat is working properly (it might be running cold all the time).

Tyre pressure is very important and must be 33PSi all round.

A tank and a quarter did me Belfast -> Milton Keynes and back, including all the detours we took via Manchester, Silverstone etc. which were easily another couple hundred miles or so on top.
And that was pushing it along a bit down the M6 / M6 Toll as the boat had arrived in late. (Rather stupidly after watching last night's Police Camera Action in which the traffic cops were standing on a bridge on the M6 Toll with a herd of marked cars waiting at the next sliproad).

A tank and a quarter did from manchester to warsaw 1324 miles fully loaded, cheaper going warsaw manchester though, diesel is 4.20 a litre here at the mo, so about 85p a litre or so:-)
Polski

Hi ...the reason why i think its using a bit too much is that i also drive an identical car regularly and that one uses no where near the same fuel and i drive it no differently...also the car in question seems alot more sluggish than the 2nd car almost as if im driving with the handbrake on or something ...if you know what i mean!!!

The problem car's Turbo doesnt seem to kick in until about 1700RPM and feels dead until it kicks in, yet the other car's Turbo seems so much more responsive at the bottom end kicking in at about 1200RPM.......this is why im wondering if somethings amiss like the Turbo.

Puggy

The turbos on the HDIs run from about 1800-3200 rpm from all accounts,
do you know the history of the other motor, could it have been remapped at any time previous to you getting the car?

other than that im not that mechanical im afraid, but have you done all the obvious things like tyres, air filter, checked the brakes aren't binding and so on?

it can be difficult when you have two cars the same not to compare but unless you know the history of both it could be like comparing apples and oranges if you know what i mean and i have heard lots of people say that you can get good and bad HDi's as far as the MPG's go.

Polski

Why not try swopping the Maf sensors over as a semi dud one of these can have quite an effect on performance, it is oonly a ten minute job with a few hand tools. Also the turbo pressure sensor next to the intercooler is easy and worth a try, dont take the small connecting pipe off the sensor, just remove the pipe and sensor as one from the intercooler pipe. The nipple on the sensor is very weak and brittle from experiance!