Fuel consumption help??

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reffro
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Fuel consumption help??

Post by reffro »

I know its a query about a Peugeot but could some of you have a quick read of this and let me know if you have any ideas.
I'll admit to having a heavy right foot, but on my last tank I got 34mpg out of my 306 TD. Its '96 N-reg with 120k miles and full service history. The fuel consumption has been dropping of late. I know its due for an oil change right now, which I'll do this weekend when I'll also change the fuel and air filter, but is there anything else that might want looking at? (Besides me cruising at 90mph). Even at 70-75mph on the M1 the other week it only hit 40mpg, so somethings not right unless everyone else tells fibs about their fuel consumption of their 306's.
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rabenson
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Post by rabenson »

Run a bottle of injector cleaner through in a tank of fuel - things might be a little crudded up.
Ron
arry_b
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Post by arry_b »

34MPG @ 90MPH isn't too bad, and the winter diesel we get at this time of the year will drop the MPG by a few. But it'll still be worth having a look around the car for leaks in the engine bay or around the tank, but they're usually easily noticed because of the smell.
My money is on it being caused by a dirtyish air filter and by your driving style. Try keeping it at a constant throttle with no rapid acceleration / braking (yes, that defeats the object of having a turbo) for a tankful and travel at 65-70. I'd expect at least 50 MPG under those circumstances, my ZX N/A D gets 62-64 in those circumstances. If pushed, and the performance of the turbo fully used, then the turbo diesels can rival a petrol car for consumption ;)
NiSk
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Post by NiSk »

1) Tyre pressures
2) Binding brakes
3) Air filter
4) Fuel filter
5) (Roof rack?)
6) Fuel leaks
Just a few of the normal causes for high fuel consumption.
//NiSk
oilyspanner
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Post by oilyspanner »

My Volcane TD gives around that ans has just started needing the priming bulb squeezing a few times each morning, Im going leak hunting.
Stewart
reffro
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Post by reffro »

I'll do the filter changes this weekend and see what happens. Its certainly not a fuel leak, and its not my driving style, I've got upto 47mpg previously driving at 70-75mph. Just in the last month and 1500 miles its dipped, so hopefully it will the oil and filters. Oh, its not tyre pressures they are checked every week, though it might be my tyres, I recently changed them, but I got the 47mpg on the first weekend I had them on. Brakes are all absolutely fine, it coasts in neutral without any braking effect, and there's no roof rack either.
This is why I'm scratching my head. The only that has changed is I've been using BP Ultimate Diesel or Shell Diesel Extra. Maybe its the change in fuel, but seeing as they are supposed to improve performance and fuel economy I'd be surprised it that. Though to be sure I'm using 'normal' diesel again.
I will run some injector cleaner through in the meantime also.
reffro
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Post by reffro »

Hmm, well as I was under the weather at the weekend I didn't fancy rolling around on floor getting cold and miserable, so I didn't do the oil and filter changes. But I have been using normal diesel again, and my fuel consumption is back to normal again. I've been driving either through London traffic, or at 90 mph round the M25, and I've averaged 40-42mpg. From which I can only conclude that BP Ultimate Diesel is complete rot.
rory_perrett
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Post by rory_perrett »

Interesting comments Reffro and Arry b. I have logged mpg for the last 7 years and noticed a dip in the winter months which I put down to the lower average temperature rather than a change in the diesel, how is winter diesel different? I'm assuming it is to do with adding something anti-wax.
The comment about the new BP and Shell blends is also interesting. From March to Sept last year I ran my car mostly on Total diesel and got around 50mpg. In September I changed jobs and started filling-up with Shell most of the time. MPG now down to mid forties which again I put partly down to the winter weather and partly down to having a shorter daily commute. While I always thought I got less MPG from supermarket fuel I never used it reqularly enough to come to a conclusion. I've seen other discussions, possibly on this forum, to the effect that often regardless of the brand name it all comes out of the same refinery and therefore must be the same. But then surely our friends at trading and advertising standards would be taking BP and Shell etc to task for making mis-leading claims about their Ultimate and Extra products.
Anyone else in a position to comment whether differences really do exist?
Regards
Rory
JohnCKL
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Post by JohnCKL »

I used 39.4 liters which gives about 450 km mix driving. That's only 32mpg for my 96 Xantia 1.9TD! Is there something seriously wrong here? Changed my fuel filter, air filter, oil, oil filter. Starting no problem (1st crank mostly), idling almost smooth but its got a chugging sound, no fuel leak (no diesel smell), fuel pump serviced. A lot of crankcase blowby, drinks engine oil. Maybe my clutch is slipping as sometimes when I accelerate, there is engine runaway until I decelerate to bring the engine revs in line. Does the last 3 problems contribute a lot to high fuel consumption or are there any other concerns I should look into?
crooser
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Post by crooser »

what method are you using to measure your fuel consumption?
cheesesliceking

Post by cheesesliceking »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by reffro</i>

Hmm, well as I was under the weather at the weekend I didn't fancy rolling around on floor getting cold and miserable, so I didn't do the oil and filter changes. But I have been using normal diesel again, and my fuel consumption is back to normal again. I've been driving either through London traffic, or at 90 mph round the M25, and I've averaged 40-42mpg. From which I can only conclude that BP Ultimate Diesel is complete rot.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
If the BP Diesel Ultimate is anything like the BP Unleaded Ulitmate, then its a big fat waste of time & money .... stoopid fecking BP petrol[xx(]
mikgram
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Post by mikgram »

I travel sixty miles a day to my work and back mostly motorway
in my Renault Safrane 2.2TD 97 at 80-85 and I get 40mpg I use Redex Diesel Additive when I fill up I put some in the tank I find the car
runs better with it . I also get better fuel economy from spring to autum than in the winter
JohnCKL
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Post by JohnCKL »

I put in a fixed amount of diesel every time, 39.4 lt or for convenient calculation, 40 lt and drive mostly around town, sometimes in the highway until the low fuel warning light comes on at around 450km or even lower and I fill up again. Could it be the tropical weather here in Malaysia or the diesel quality here, sulfur specs below 3000ppm? My cold start device is not working either, I think. There are no premium diesels here, only one type of diesel for all brands and I am using BP. Diesel additives doesn't seem to work for me, in fact, it seems to worsen the mpg. I've tried a few and were never successful in improving mpg at all. It could be the short trips I make mostly (a few km) and not enough long distance travel (sometimes 20-50km per trip) doing 80-110kph (50-70mph). Tyre pressures are checked OK, brakes checked by mechanic, not binding and no roof rack. Injectors need servicing?
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Post by jono »

Interesting comments regarding Shell and BP diesel. Since buying my Xantia Hdi in October 03 I have only used Shell diesel. When filling up recently I have noticed more diesel foam in the filler neck than usual and whilst driving at night, slight exhaust smoke noticeable in the headlights of the car behind. I am wondering if the anti waxing additives are lowering the fuels combustion ability thus causing poor mpg. I have just filled up with supermarket diesel to see if there is any change in the mpg and as the commute to work is the same every day. Results could be interesting.
Jono
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