Ordinary Fuel Economy from my 02

[RollaRollin]

I've been driving my 2002 Ascent (ZZE122R) around for about a week or two now and noticed I wasn't getting the greatest fuel economy.

Decided to do a little bit of testing.

I let the fuel light come on, and then put in $15, which was 10.43L at the time.

I got exactly 130km out of the 10.43L before the fuel light came on again.

During that time I drove on pretty much on highway roads. With the occasional bit of city driving.

I'd say 110km was on highway and 20km was done in city driving.

Just looking up the specs of my car, it says it should be getting, 5.8L/100km from it on the highway, now I know thats at best conditions but if you work it out I'm currently getting like 8.5L/100km, and I don't drive hard, thats just cruising in 5th gear (90km/h P Plater).

Thats pretty much an extra 3L burn every 100k I drive, compared to what its rated for. Heck in city driving its rated for 8L/100km. And I'm doing worse than that out on the open road.

Is this normal for my car to be giving such ordinary fuel economy?

And if not where do I start to fix this problem as its already starting too add up ):

Appreciate it,

Cheers

[RollaRollin]

Took out the MAF today and gave it a clean with MAF cleaner. (see pic beforehand)

Also took out the Air Filter, looks dirty as! (see pics)

Will have to replace that as soon as I can!

Any tips on how to clean the one I have?

Pretty dodgy but I won't be able to get to Supercheap or Autobarn till Friday at the best so I'd like to just give it a clean if possible

Also did the 30min ECU reset (:

Will see how I go

Any other things I should be looking at?

*ps sorry about the size of the pics, dont have my jpeg compressor on the mac

Edited March 28, 2011 by RollaRollin

[munter]

Any other things I should be looking at?

Have you checked your tyre pressure? Low pressure can eat into economy. I usually run around at about 40 psi.

[69.NIX]

Simple checks and servicing should make it go better.

I've notice that after a fuel injector clean, I get some great economy runs.

Maybe try some 98RON for a tank or two, then see if this makes a difference. Also, check for plugs and leads!

[RollaRollin]

@munter

I haven't checked lately but im pretty sure they are right

Do you think 40 is a bit too high mate? Just reading the manual and they mentioned 32 psi

@BG Pete

Definitely will be servicing soon, almost time for the 195,000k

What simple checks would you recommend mate?

And by injector clean, do you mean removing the whole rail or just a bottle of injector cleaner?

New plugs will be done at the 195k

Cheers guys

[2204]

mate i felt as if i had the same problem as you what i did was i gave it a good service and changed my fuel filter as well, when i took out the fuel filter at the mechanics is was bloody dirty, car is great on fuel after the service and changing of fuel filter

[Hiro]

I let the fuel light come on, and then put in $15, which was 10.43L at the time.

I got exactly 130km out of the 10.43L before the fuel light came on again.

During that time I drove on pretty much on highway roads. With the occasional bit of city driving.

I'd say 110km was on highway and 20km was done in city driving.

Always calculate fuel economy from a full tank re-fill, it reduces the inaccuracies in the calculations substantially. The fuel light won't consistently come on at exactly the same litres-left-in-tank - if it comes on at 10L left and you only fill up 10L, and the next time the light comes on at 11L left, you're calculating 9L of use but assuming 10L, which is a 10% error. The same 1L difference on a 40L refill is only a 2.5% error, which is much less.

Basically, fill the tank up to the brim (say, second click) and reset your tripmeter. Then, drive around for several hundred km so that you get significant fuel usage (try to use a full tank if necessary). Then, refill the car up to the second click again (from the same station/bowser if possible), and divide the number of litres you put in by the distance travelled, then multiply by 100 and you'll get your L/100km use. The only problem with this method is that it is hard to isolate one particular driving condition (ie city, freeway, Sunday arvo etc), but is perfect for an average. The good thing is that it totally ignores any inaccuracy in the timing of the fuel light (since you're not relying on it at all as a measuring device) - the only errors can come from the bowser not clicking at exactly the same tank level (but once again, a litre or two over a full tank isn't that much of an error), and the accuracy of the odometer/tripmeter (standard tyres should be fine, aftermarket rims/tyres may put it out by a few %).