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6th November 2010, 06:31 | #1 |
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diesel consumption again............
chaps,
this is now frustrating me as i cannt work out if the car is running efficeintly so i would appreciate input. Now running around on short journeys i sort of accepted 27.9mpg average (ipk)..........but i went to cornwall and back. At the end of the down leg the computer upped its average to 31mpg. Now on the way back i did a brim to brim fill. Driving was approx 50miles faffin around cornwall and 365 miles home. On the way back i did hit traffic. Now a brim fill showed i had actaully averaged 38mpg yet my IPK showed 32.8mpg.......... i know the brim fill is the best way but would memebers still say my car is poor on consumption ?........i just need to know if i should be looking at doing something (i have ordered a tuning box) any ideas
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6th November 2010, 06:44 | #2 | |
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But what 'tuning box' have you ordered? A faulty MAF can cause fuel consumption issues but for resolving issues with them anything other than one of Rover Ron's Synergy boxes is dubious at best. And do a search for setting the trip computer, I recall there is a thread somewhere about how to adjust it so that you get a reading closer to your actual fuel consumption. Worth remembering the trip computer is just a computer - and 'garbage in equals garbage out'. There is no point in believing an instrument that is not error corrected. |
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6th November 2010, 06:49 | #3 |
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done
Hiya,
yep done all the filters....and all the basics. MAF appears to be working fine but i cleaned it anyway. I bypassed the EGR...... i just feel 38 is too low and its even worse when i faff around locally!
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6th November 2010, 08:43 | #4 | |
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Quote:
Either way, your mpg figures are terrible compared to mine, so I can only repeat again what you seem to have already done. Your touring run should have produced nearer 50mpg if a manual. EGR, PCV, MAF - air filter and driving style. The Synergy (if that is what you meant) will not fix other issues, sort those out first - then you might see some small improvement with the Synergy.
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6th November 2010, 08:50 | #5 | |
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Recently?
Cleaned it and it made no difference? Could it have been faulty to start with? With what? Quote:
FWIW I have been getting an average of 43.6mpg - with a best of 50.5 and a worst of 36.1 - and yes I am dull enough to have kept a spreadsheet of my consumption for the past year. The consumption improved after I serviced it fully just after buying it. This dropped again in the cold in the winter but rose in the summer (I put this down to the thermostat not working - still not changed....) Note - the majority of this has been with the Synergy set to '10' and a Pierberg MAF - but I did not notice a significent change in fuel consumption with it. I presume because my MAF was in fact knackered when I got the car. As a whole the car goes much better now than when I bought it and it seemed to be OK. Also I know my fan is on the way out and so I don't use the air con much at all. |
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6th November 2010, 09:40 | #6 |
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filters
Hiya,
appreciate the advive. Yes filters done in last 1000miles....remind me about the PCV? i donnt reset every time ironically if i stand the car at Idle the heater blows coldish....when its running its as hot as i would expect?
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6th November 2010, 10:02 | #7 | |
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PCV - small filter unit near the top of the rear of the engine, should really have been a service item on the diesels, has now been superceded by a fit-and-forget version from BMW. Surely if you don't reset every time, you're logically inevitably going to get a different figure from the brim calculation, because the IPK will be showing an average since it was last reset rather than a figure for the tank in question? Seems likely that your thermostat is suspect - a mildly faulty one will be preventing the engine getting up to optimum temperature and therefore hurting mpg.
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6th November 2010, 17:26 | #8 | |
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The thermostat is now the only common suspect left (coolant temperature in the low to mid 80s), but I'm beginning to doubt whether running at 90C - 92C is going to get me the manufacturer's stated average of 40ish combined and the high 40s on a run. There's got to be some other factor. What about the injectors? Anybody changed them and noticed an improvement in consumption?
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6th November 2010, 17:48 | #9 | |
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