My car is lying to me !!!!!!!!!!!!!!!!!!!!!

[ahmedomnnea]

Hi there,
I'm Ahmed and I live in iraq, my car is simply lying to me about fuel consumption, in the trip it shows that the fuel consumption is in about 14L/100km when accelerating rapidly but within seconds it gets back to 6L/100km when on 4th gear steady driving, so far sounds great right?
but here is the problem, I refill the tank to the top (75L) and reset the trip meter at the gas station and start driving for a week or so and I always do (200Km +/- 20) and go to refuel and it takes (45L) to get the tank full, with little math I get about 20L/100 which is not what my trip instantanous fuel consumption tells me which is an average of 10L/100, what the ....?
please help me because you are the only ones who can help, I'm in iraq and we dont have Holden services so if you can guide me I can get it fixed myself.
thanks.

My car:
10/2001 Holden VX
ecotec 3.8L V6
Automatic Trans.
All stock, No mods. of any kind.

[bozz73]

Hi Ahmed

Did you fix the vibration problem?

What is the average speed you are doing when you get that sort of fuel consumption?
Also what sort of driving assuming you are driving normal.
Are you doing lots of stop-starts, traffic jams, or, plain motorway sitting on 90-100km/h all the time....???
What kind of fuel are you using? 91, 95, 98 Octane?

I think my computer is not completely honest with me either, can't remember if it was indicating to much or too little.

Cheers

[ahmedomnnea]

Hi bozz,

I still have the vibration problem, next week I'll go to baghdad to fix it.
my average speed is 60Km/h.
my driving is very normal and yes we have traffic jams.
but is that gas mileage normal because the people here in this forum talk about lower gas mileage they get with their cars.
thanks.

[NickVR]

Are you running ethanol blended fuels? This may be the reason for high consumption and inaccurate reading. It may need the software reset or upgraded.

[bozz73]

what kind of gas, 91, 95 98 octane?
Mine does 12.1/100km with a chip and some minor intake mods in urban traffic with some motorway driving.
Would do 10/100 on motorway traffic alone easily.

Fix the vibration problem first,
It was a cracked flywheel right?
If this would trigger the knock sensor it might account for some bad fuel economy.

After you've fixed it fill up the tank and go for a long drive try 100km and if possible try it on the motorway and get an average of 90-100 km/h.
At the end of the drive fill up again. If you don't get any better than 15/100 you definitely got a problem.

[Full Spectrum]

Gday mate.

Tell you the only thing you can trust on the Holden trip is fuel used. Everything else lies.

[codeunknown]

ok...ahmed......
if your heavy on that right peddle to go go peddle.....nothing anyone can do for you...

you nearly got the same running gear as me...i got a vt with vx engine with a auto....
and on nice open roads i get 7.85 l/100kms as a average...

you have however i think the 3 dash trip computer and i have the 1 dash trip computer....

when you put the foot down....your meter should read anywhere from 14L/100 to 17l/100 or higher...
why because its measures the fuel your feeding each injector right then and says ...if we keep this up...
soon as your take foot off or ease off it measures the flow then....which will be idle point flow or more...
and that happens to best possible use 6.6l/100km

the fact you hammer that foot for so long eats your fuel....
if you look at the other posts here on fuel consumption....
you see the rougher and heavier you are on the gas the more likely your use will be high...

i also bet your have the power button engaged all the time...as well
so learn to switch that off ..........its only there really as toy or for towing withe auto trans....

also if you have traction control...which that off as well......

now the E10 is different to unleaded and max power unleaded...
E10 is low load ---low power fuel...its ment to be driven easy.....and it gets brilliant returns...

a max or unleaded might be better for you until you learn to control that heavy foot

also if you have mags on the car.....are you checking the tyre pressure ? big mage low of air pressure suck the guts out of the car!

so you might alos be better with standard 8 inch tyres...then big 10-12inch !

but so far from what we know...about you and the car.....its your driving causing issues...

check the other post on here and see what others get..who have a heavy foot too...

[ahmedomnnea]

Hi codeunknown,
thanx for the reply, my vx has one dash trip, and easy on me man !!!!, you presume that I have a heavy foot which isn't true, when I accelerate I don't let my rpms to exceed 2000rpm when the gear is shifting up, power button off always and also trac. control is off, I check the tyres pressure weekly, another thing got me interested I disconnected both O2 sensors and no check engine light on the dash !!!, is that normal? and if not then what is it? also noticed that I have a MAP(Mass Air Pressure) sensor which I think that commodores doesn't have??!!

[codeunknown]

i be checking that....and i be maybe replacing the o2 sensors...or cleaning the others and refitting..make sure you use high heat grease on the threads....ist possile the leads to them are dead....
its also possible the sensors are so dirty from overrich fuel ..they are not reading right...

perhaps you got a car in need of service.....spark plugs and new leads...and new air filter..for starters...
check the timing...
check the fuel control...maybe the maf unit is buggered...or out of wack...

the car is 1999--2002 age wise....with how many kms on the clock....

sorry about the lead foot ..often that is the cause...

[codeunknown]

look also ....the injectors may need a clean and the maf thottle body etc may also need cleaning...

you seem to have a rich running engine....

when its cold...and first starts how good and stable is the ilde...and does it get worse as it gets hotter..less stable
whats the idle on when its first started to warmed some 5 mins later to after its had 1 hour run....
i think its running rich

so be checking the sparking and timing and getting fuel control