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Steve Ashworth

Active Member

• Feb 4, 2011

• #1

Last month or two my mpg has dropped from about 12.8 down to average of 9.5. Quite a significant drop... Its very hilly where I live hence low mpg.

Even on motorway its dropped from 20 down to 16.

What can cause this?

In last 6 months I've had new crank sensor, plugs, leads, maf sensor...

No misfiring according to faultmate..

Where do I start looking?

Cheers,
Steve

 

wammers

No longer with us, RIP

Donater

• Feb 4, 2011

• #2

Steve Ashworth said:

Last month or two my mpg has dropped from about 12.8 down to average of 9.5. Quite a significant drop... Its very hilly where I live hence low mpg.

Even on motorway its dropped from 20 down to 16.

What can cause this?

In last 6 months I've had new crank sensor, plugs, leads, maf sensor...

No misfiring according to faultmate..

Where do I start looking?

Cheers,
Steve

Click to expand...

Air filter. Take it out for a couple of days and see if mileage goes up.

 

rasheed

Well-Known Member

• Feb 4, 2011

• #3

o2 sensors? did you reset ecu long term trims after the new MAF etc?

 

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Steve Ashworth

Active Member

• Feb 4, 2011

• #4

Will try it and see, although it also had a new air filter in December..

Cheers.

 

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Steve Ashworth

Active Member

• Feb 4, 2011

• #5

After I changed MAF, plugs n leads I reset adaptive values if thats what you mean?

What readings should I get from O2 sensors..

Cheers

 

wammers

No longer with us, RIP

Donater

• Feb 4, 2011

• #6

Steve Ashworth said:

Will try it and see, although it also had a new air filter in December..

Cheers.

Click to expand...

Then it seems like a match to me. New air filter in December mpg drops for last couple of months. Lets see December, January how many months is that?

 

3.5 efi

Well-Known Member

• Feb 4, 2011

• #7

cold months

 

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Steve Ashworth

Active Member

• Feb 4, 2011

• #8

wammers said:

Then it seems like a match to me. New air filter in December mpg drops for last couple of months. Lets see December, January how many months is that?

Click to expand...

mmmm dont know why that should be but...worth a try

 

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Steve Ashworth

Active Member

• Feb 4, 2011

• #9

3.5 efi said:

cold months

Click to expand...

Its not that cold now (10deg C) but only got 9.6 mpg today...

 

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Ridesafe

New Member

• Feb 5, 2011

• #10

Make sure air filter seated properly, if it's an aftermarket jobby fooook it off and get OEM - more to buy but wont drop your economy/power!

 

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Steve Ashworth

Active Member

• Feb 5, 2011

• #11

tried it without air filter as suggested but no difference?

 

juiceyv8

New Member

• Feb 5, 2011

• #12

thermostat??
water temp sensor??

 

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Steve Ashworth

Active Member

• Feb 5, 2011

• #13

Temperature gauge doesn't deviate from normal once warmed up (a few minutes)?

 

Last edited: Feb 5, 2011

jt_armstrong

Well-Known Member

• Feb 5, 2011

• #14

Have you changed where you buy your fuel? I noticed my MPG dropped when I used Jet compared to BP or Shell.

 

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Steve Ashworth

Active Member

• Feb 5, 2011

• #15

no - I buy mainly from same place, although it is Jet.
WOuldnt expect 25% less

 

jt_armstrong

Well-Known Member

• Feb 5, 2011

• #16

Steve Ashworth said:

no - I buy mainly from same place, although it is Jet.
WOuldnt expect 25% less

Click to expand...

Nothing scientific but I reckon my MPG was dropping by about 10-15% with Jet. 25% is big time bad.

 

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Steve Ashworth

Active Member

• Feb 5, 2011

• #17

Does anyone understand the O2 readings that show on diagnostics.

Live data sample attached...

cheers

 

Attachments

• o2.txt

  12.7 KB · Views: 237

ladyranger

Active Member

• Feb 5, 2011

• #18

I'm really sorry and i know i will get all sorts of greif about saying this but....it';s JET FUEL!!!

i have done extensive trials with filling from different garages and the worsed is jet! i get 12mpg from jet and 22from shell sorry, i know everyone will say there is no difference but try it for yourself. go fill up at shell and see if your MPG returns...i'll bet it does!

 

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Steve Ashworth

Active Member

• Feb 5, 2011

• #19

In that case my next fill will be BP, its just that I pass the Jet station.

PS it wont take long to need a refill!!!!!!!!

 

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Ridesafe

New Member

• Feb 5, 2011

• #20

Got a very good chance; Jet, just like super-markets, spot-buy fuel that is very near use/sell by date, hence keeping prices lower than BP, Shell etc. Furthermore, their own refined fuel is only filtrated 2 -3 times, as opposed to Shell (5x) Bp (4x). This makes the petrol "cleaner", removing particulates that "dirty" the fuel and lessen it's efficiency.

Shop around, try different local fuel-stops, all vehicles run better/faster/more eonomical on different fuels. Personally, I run all my bikes on Tesco Momentum (higher Ron and more mpg), the Range is better on BP fuel, but lower mpg on morrisons or tesco standard unleaded!