vitara fuel consumption

[paulyp]

hey everyone i have some questions about the fuel consumption of my vitara. i dont kno if its the done thing but i always fill up with premium fuel but seem to do 18-19L/100k's. even highway travel does not seem to be any better. my vitara is a 96 2.0L V6.

i kno that fitting exhaust/snorkal can help, would like to know how much it does and how much it might cost?

also does anyone kno of switching to gas?

appreciate any info
paul

[Gwagensteve]

It will send you broke at this rate mate!

At a guess I'd say it's not coming off of open loop mode or alternatively it's staying on "choke" (i.e its running super rich because it thinks it's cold.

Replace 02 sensor/s as a start. If they've got k's on them they're probably shot they will make it run rich.

Some fault conditions won't fire the check engine light, but I have to ask - are you getting a check engine light?

I would spend some $$$ (hell, atm your just ripping up cash driving down the street) and get it on a dyno and get the air/fuel ratio looked at. my guess is it will be very rich.

You should get not worse than about 14l/100km and maybe 11-12 on the highway. - it's only making about 140hp! our STi makes twice that, probably weighs more, is constant 4wd and makes just over 11l/100km in mixed driving.

Steve.

[cj]

seem to do 18-19L/100k's. even highway travel does not seem to be any better. my vitara is a 96 2.0L V6.

You have a real problem. Standard the manual gets 10.4l/100km and the auto gets 11.6l/100km. Even with big rubber (32") you shouldn't be much worse than 15-16l/100km. As Steve said I'd look at the O2 sensors initially if they have some km's on them. The MAF sensor could have build up which you could remove and spray with contact cleaner. Has anything been apart on the engine? If so, you might have a vacuum leak which wouldn't help. How dirty is your air filter and fuel filter? Are your brakes dragging at all? Is your Cat clogged? You could have fuel pressure or injector issues or a faulty ECM, EGR, Throttle Position sensor or Engine Coolant temp sensor.

[paulyp]

yea im running 31's and the engine has done just over 200k, i tend not to tamper with the engine but i think i will have to! where can i find these parts you speak of, lets start with the 02 sensor is that the one in the air box? and as for maf sensor and other sensors im lost. i am getting a service done this week so that will replace all my filters however they are pretty clean. brakes dont drag i know that just had them replaced.

a vacuum leak might this casue lumpy idle? beacuse i used to hav that problem but now has been fixed so that could be ruled out also?

could i get a few more details of how to do these things cheers
paul

[cj]

You have two heated O2 sensors, one in each exhaust manifold. Use Bosch Universal O2 Sensors LS 07 part # 0 258 986 507-36Y. You will need a 22mm spanner. The drivers side is "relatively" easy to get at but the passengers side is a bit of a pain. I ended up getting a cheap 22mm spanner from Bunnings for $1 and cutting it in half to fit in the space available then used a length of wood on it and hit it with a hammer. The instructions included with the O2 sensor are pretty easy to follow and it is much cheaper than buying genuine parts from Suzuki. At the mileage your engine has done they certainly should be replaced anyway. Start there and see how you go.

[zooki]

what makes you think the o2 sensors will make a difference? in reality the computer looks at them at idle and cruise to trim the fuel by a few %, there is a major problem here

I would check the coolant temp sensor, the computer might not think the engine is warming up (and check the coolant temp, it might not be warming up)

does it idle and drive well? airleaks as already said will have a big effect on power needing you to put your foot down more

have you adjusted the km you are doing with the bigger tires? 31's will mean you are doing more miles than the odometer says to the tune of 10-15%

I went form a percieved 16/100 to 9.2 by working out actual km travelled and cleaning the airflow meter and doing up a few hose clamps

[cj]

what makes you think the o2 sensors will make a difference? in reality the computer looks at them at idle and cruise to trim the fuel by a few %, there is a major problem here

I would check the coolant temp sensor, the computer might not think the engine is warming up (and check the coolant temp, it might not be warming up)

does it idle and drive well? airleaks as already said will have a big effect on power needing you to put your foot down more

have you adjusted the km you are doing with the bigger tires? 31's will mean you are doing more miles than the odometer says to the tune of 10-15%

I went form a percieved 16/100 to 9.2 by working out actual km travelled and cleaning the airflow meter and doing up a few hose clamps

A bad O2 sensor on mine altered the mileage by a good 3-4l/100km. They do not have an infinite life and with the km's mentioned would probably not be helping. As you will note I have also mentioned things like the coolant temp etc. As you point out if the mileage hasn't been corrected for the larger rubber then the figures will be significantly out too.

[Gwagensteve]

what makes you think the o2 sensors will make a difference? in reality the computer looks at them at idle and cruise to trim the fuel by a few %, there is a major problem here

I would check the coolant temp sensor, the computer might not think the engine is warming up (and check the coolant temp, it might not be warming up)

does it idle and drive well? airleaks as already said will have a big effect on power needing you to put your foot down more

have you adjusted the km you are doing with the bigger tires? 31's will mean you are doing more miles than the odometer says to the tune of 10-15%

I went form a percieved 16/100 to 9.2 by working out actual km travelled and cleaning the airflow meter and doing up a few hose clamps

15% of 19l/100km is 16l/100km which is still miles too high.

Could be coolant temp, true, but at 200k the O2 sensors will have to be stuffed, they're not rated for that life.

It's not the amount they are trimming the fule that's the problem, it's that an out of target figure on the O2 sesnor, that doesn't correct when fuel is trimmed, will hold the car in open loop and it will be thirsty.

As they must be past their best and can be easily changed, they're a useful starting point.

Steve.

Steve.

[MightyMouse]

Issues of short and long term fuel trims might not be relevant to Vitara's of that age. A lot of computers around that age were quite dumb ( work well however ) - its the more sophisticated later models that had all the bells and whistles. Trims becam virtually mandatory with the introduction of OBDII.

THe o2 sensors are a very important part of the control strategies of ECU's of around that age ( and still are ), and are not usually useable at that sort of distance.

Not being a Vit expert - here's some things to look at :

1/ O2 sensor - bad ( my No. 1 pick given the k's... )
2/ Map sensor - out of cal /air leak etc
3/ Air and coolant temp - out of cal / disconected etc
4/ Fuel pressure - too high, no vac line on reg etc
5/ throttle position sensor / switch - if switch not working ( car staying in open loop )

[paulyp]

i just droped it off at the mechanic and he said the exhaust is about to go, that could contribute im sure. but i also asked him to replace the 02 sensors and have a look around for any other fuel guzzling related problems.

on another note an exhaust thats on the way out means i have a reason to upgrade!!! i have herd 2" is the way to go?

any advice on this one? cheers
paul

[cj]

I'd have a look at 2 & 1/4"

[paulyp]

hot damn just picked up my new vitara, well so it feels with the new 2 1/4 exhaust! 02 sensors are all good and still working also so the main problem must hav been my shitty old exhaust. sounds so good! very pleased. im still going to look into the other things mentioned

Map sensor - Air and coolant temp - Fuel pressure - and
throttle position sensor / switch

but my only problem is where do i find and hiow do i fix these things?

cheers
paul

[MightyMouse]

Who tested the O2 sensors and how ?
What Lambda is it running ?

O2 Sensors dont just age in terms of their high/low switching characteristics, they also drift and slow down. Any one of these faults can make the sensor useless.

200 thou is about ( and I admit it varies from manufacturer to manufacturer ) twice the life quoted by the manufacturer.