Increased petrol consumption

P

PhuketZ4

Member
Hi ladies and gents, my 3.0i has suddenly started using much more petrol, I can't see any leaks, there's no petrol smell, tick over is as usual. My last tank of gas lasted only 213 km. My average driving speed is very slow as Phuket is full of tourists and the roads are jammed, so, a lot of stop start motoring.
I filled up this morning, the dash said 405 km to refill, I drove 9 km home, now it says 383k, thats 22km not 9??

Any thoughts/help appreciated,many thx.🙂🙂
 
Sudden changes like that are usually caused by a sensor failure..maybe the exhaust gas sensor…a code reader would be your first call…
 
Hi, I don’t know how accurate those gauges are, it would be better to go old style and fill up the tank, make a note of the mileage. Drive until quarter full, top up, check mileage again. Subtract one from the other and divide by the galls or litres to get your miles. :thumbsup:
 
Has anything changed - if you've used a different filling station that might do something - my car (2016 with the N20 engine) can be very picky (hates Morrisons but likes Shell).

Has the traffic changed, I found that my daily economy varies from 25mpg in parts of London to 33mpg in Essex as I get a chance to get the car properly warm up between visits.

Start stop also makes a difference, if its not working (battery is on its way out) that will also make a "small" difference.

I always look at the cheapest solution first, but a code reader will help
 
The gauge is never accurate, it calculates usage based on how the car is driven, my car can show 350 miles but as soon as I drive in town, it will drop very quickly doing exactly what you have described on the gauge.

I do what Mike has advised on ever tank as I am anal and it works pretty well
 
Take a look at the fuel trims using diagnostic scanner that can view live data. High fuel trims are usually caused by a vacuum leak between the intake after the Maf so you need to check over the entire engine from there to the exhaust and all rubber and plastic pipes. Also check the rear edge of the inlet manifold, there are unused ports on there that have rubber sealing caps on them, these rot and split and fall off allowing unmetered air into the system, hence high fuel trims and reduced mpg. Best to smoke test the engine to find any leaks you can’t find visually. If you have a plastic cam cover check that out, they are known to degrade and develop cracks due to age and repeated heat cycles. Replace any bad hoses you find, these engines require a sealed vacuum system to run correctly. Often forgotten is the O ring in the dipstick tube on models with a dipstick, they go bad with age and allow air in.
 
Didn't we have this the other week?

You also don't say how empty it was when you filled up or whether you filled up completely last time - 213km is short on 50l (about 10mpg) but not impossible if it was all stop/start, and not too bad at all if you only put 35-40L in.

The display uses loads of assumptions, I think it uses average consumption over the last 50km to guess how long the rest of your fuel will last (it tells you in the handbook).

As an example my Toyota said I had 600 miles when I filled it, 100 miles of running around town and I've only got 300 miles left. Tonight I'm going to be on the motorway for the first 15 miles, and I'll bet the "distance to empty" goes up as I drive along.
 
Fill up and reset your average fuel consumption, average speed, mileage etc. and check again.

If you have a code reader with the feature, then reset your adaptations. This essentially means that the car relearns your driving style over a period of time.
 
I would ignore the gauge based on such a small sample of driving. As others have said you need to run a full tank down, do some miles and then refill noting the top up volume checked against the mileage covered. Make sure you can refill to an known accurate level. I make sure I visit the same pump, and fill until the gun cuts out, wait and repeat a few times so it settles. That test is as accurate in my view as you can get.
 
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