I have had bad fuel economy (3.0L V6 - uses around 15L per 100kms).

Anyway, I had my fuel filter replaced (it was very grotty), and had the injectors cleaned onboard.

My next tank of fuel lasted a bit longer... got around 13.5L for 100kms, so about an extra 50kms per tank.

However my next fill up the fuel economy is back at around 15L for 100k again :( I'm thinking perhaps the tank is full of sludge or something?

Has anyone ever had their tank drained and cleaned?

Kim

Whats your air filter like?, is it auto or manual, are there any exhaust restrictions and do u have any mods on the driveline and lastly how heavy is your right foot?

I get about 450k's out of my work wagon 3litre auto, it gets a fair hiding not all the time tho and its badly overdue for a service.

when you say 450k's... is that on a full 64L tank or from say a 45L fillup?

The car is auto, I have a 2 1/2" muffler, foam air filter that is clean, run Premium Unleaded, and my right foot is averagely heavy. I've tried driving like a grandma and it doesnt make much difference... :|

i get 10L per 100km
last week i got 9.something
and i don't drive like a granny
when was the car last serviced?

car was serviced not long ago - new plugs and leads at the same time as having the fuel filter and injectors done.

On highway driving it only uses around 10L (9.3L was the best) for 100kms... I do a lot of start-stop city driving though.

i have the same problem too, same engine, no mods, just K&N panel filter, new plugs, leads, and cap. not too sure about the fuel filter, looks like it's about 2 years old or something, got this car a year ago. any suggestion? btw it's auto....

so yours is the 3.0L V6 too? Did you have your injectors cleaned too, then it got bad again?

What sort of economy are you getting? Exactly the same as mine?

I'm taking the car back in next week so we'll see I guess :| $$ :(

yes, and sometimes it may go worse than that like 16-17L/100 km :( timing adjustment was done recently, so guess shouldn't any prob on the engine. i felt the car isn't responsive for pickup.

what i'm looking now is prolly the auto trans, loose band or something so the engine isn't synchronized with the tranny? any idea people? i'm so desperate to find out.

and how much is it do you guys reckon for auto-tranny band adjustment?
thanks..

i wouldnt have thought tranny probs would cause bad economy? Hmm.. or maybe it could. I dunno.

I'm getting my fuel pressure regulator checked... and also getting it put on a tunescope again. Will let you know what the outcome is.

i used to work as a pizza delivery driver
which involves stop start driving and i would get 12- 13L per 100km
maybe problem with stepper motor i had a prob with stepper motor and the plugs were ancient got that all fixed and bingo 9-10L per 100km but now more cruising less stop start but i still drive it pretty hard some of the time

nah the electrical system on the car should all be good... have new plugs, etc.

Because it worked for 1 tank after having the filter/injectors cleaned but then the next tank it went bad again, it makes me think theres something in the tank (gunk) clogging up the filter or injectors.

attached is a excel file (unzip it first) that is useful for working out fuel economy. Thanks to Mal for helping me out with the formulas.

ur car is a auto right?
they tend to get worse economy than manuals
but still don't explain ur poor economy
its not something silly like u have ur air con on?
run a bottle of that injector cleaner through
try a tank of premium some ppl say that is good for cleaning injectors and stuff, maybe ur body kit is affecting ur aerodynamics

i got no idea ay
see what ur mechanic says

Hmm, nice spreadsheet... when I remember, I'll use it.. thanks :D

injector cleaner doesnt make a difference (have a bottle in there at the moment). Running Premium or Unleaded makes little difference either. Only have the sideskirts on the car at the moment... so shouldnt be an aerodynamics issue either.

Will keep you posted :)

speaking of side skirts, what sort do u have?

they are veilside (did i spell that right?) style... not sure who actually made them tho.

A good thing to look at would be your injectors, clogged injectors cause poor fuel economy due to the spray being less effecient in mixing air with fuel. The best thing to do is have them ultrasonically cleaned.

where would u get ultrasonic cleaning done and how much is it???

Tim

for a bodykit to drag a car that badly you would have to be towing a parachute lol
The ultrasonic clean and flow/spray pattern test is the first thing to look at.
Next is also just as important, injector seals, inlet gaskets and throttle body.
All these items have been in service for 10+ years and will require attention.

I get like $10 bucks of petrol like 10-13litres.... and only get 50-70km and i live in parramatta sydney so yeah its like stop and go type of driving.

On freeway/high way without much stop/go I get $10bucks/10-13liters 80-100km.

Car service was due at 120,000 its like 125,000 now.. Anyways let me know if you find out what suck so much petrol.

I always have to spend $10 everytime i wanna do 70km. :/
Going 4 days a week is like $40-50 of petrol for me :(

and when I like to speed with a heavy foot... 10-13 liters only takes me 40km. :S

it hurts when you dont have a job either :S

just a little bit update on my car situation, i just change the intake resonator into a powerade cap to seal the hole, and walah, i got like 12-13L/100. looks good imo, since i used to have 15-16L/100 car :lol:

looks like the resonator has a leak or some kind. well, it's good to have more mileage on the ol bastard :lol:

oh cool, i just did the Poweradecap mod too...hopefully some more mileage :lol:

It wouldn't make a huge change...but tyre pressure can affect both performance as well as economy

keep em pumped up an you will notice a difference