Sudden fuel usage increase - Nissan-Navara.net
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post #1 of 15 (permalink) Old 08-01-17, 01:32 PM Thread Starter
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Sudden fuel usage increase

Morning guys over the last month ive noticed my mpg has been slowly going down so last week i reset my computer to get a weekly average and im getting 21mpg on a standard week and i used to get 28-29mpg
Euro 4 automatic 60/40 motorway/ A roads
I do more or less the same route day in day out every week for the last 3 years so my milage and route havent changed so it's the the truck thats some how become less efficient
Anyone got any suggestions what i can check?
The filters religiously get changed every 6 months (last changed in October) and im still useing bp for my fuel
The only other thing ive noticed is when the engine is cold if i give it full boot as in wheels spinning, it sometimes dumps a brick and looses all power untill i shut down and restart but if being run for 5 minutes or more its fine
But its been like that over a year and dosent seem to be getting any worse
Im suspecting the suction control valve for that but havent been able to confirm yet and cant see how that could affect the recent mpg loss
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post #2 of 15 (permalink) Old 08-01-17, 01:53 PM Thread Starter
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Just realised ive posted this to the wrong section if a mod could move it to technical for me please?
Thanks
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post #3 of 15 (permalink) Old 08-01-17, 03:26 PM
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If you dpf has done a regen in this period you would see a spike, other than that a dirty maf might be the problem.
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post #4 of 15 (permalink) Old 08-01-17, 06:35 PM
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Back to basics, check rear drums for handbrake locking on, common fault on D22's, don't know if the same applies to 40's?
Similar system and layout though.

Very first upgraded D22 - 10 years and 72K miles and still going strong!
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post #5 of 15 (permalink) Old 09-01-17, 12:00 AM Thread Starter
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Never thought about brakes ill check them tomorrow
Wouldn't have thought the maf would be dirty cos i regularly change the filters and its got a egr blank bjt ill give it a good squirt with contact cleaner just in case
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post #6 of 15 (permalink) Old 09-01-17, 09:58 AM
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It is the hinge point of the lever that tends to seize up.
Best to access it from the 'works' side after removing drum, as from the rear, it is inside a rubber gaiter.

Very first upgraded D22 - 10 years and 72K miles and still going strong!
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post #7 of 15 (permalink) Old 09-01-17, 10:04 AM
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If everything else seems to be running normally, check tracking/wheel alignment. Surprising how much fuel can be wasted heating up the tyres...
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post #8 of 15 (permalink) Old 09-01-17, 10:43 AM
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Quote:
Originally Posted by freemansteve View Post
If everything else seems to be running normally, check tracking/wheel alignment. Surprising how much fuel can be wasted heating up the tyres...
Years ago in Cortina days, it was calculated that 1/2" out in the alignment specification was equivalent to dragging the front axle 90' sideways for every mile travelled! (courtesy Haynes).
This on 13" wheels with 4 1/2" wide tyres.
Navaras are much, much bigger.

Very first upgraded D22 - 10 years and 72K miles and still going strong!
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post #9 of 15 (permalink) Old 09-01-17, 12:49 PM Thread Starter
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Mmm interesting i did have my tracking done about a month ago because i was burning tires
Might be worth having them recheck it to be sure
think its still inside the 30 warranty so he should do it for free
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post #10 of 15 (permalink) Old 09-01-17, 03:47 PM
Overdrive!
 
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Tracking is often set incorrectly by technicians; lots of bad data out there. It may also need to be set differently if tyres are not 'standard' circumference or if vehicle has been raised. Or if wheel offset is non-standard.

I'd see if I could find the correct data on tracking myself and check it against what the tech thinks. But this may be red herring for fuel consumption...
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