pcmhacking.net

Hi Peeps,

First post and was after some information.

I currently own a V6 VX Series 1 which recently developed fuel consumption issues.

So far i have replaced both o2 Sensors, Replaced the TPS and cleaned out the Throttle Body and Idle Controller.

Initially i was getting around 17-17.5 per 100km and brought the above brought that down to around the mid 13's per 100km.

Now to achieve the 13 mark i have to basically baby the car. Which is becoming frustrating. (was doing this when the car was getting 17's per 100km)

My question is there a Smaller Flowing Injector that is plug and play?

Reason i bring this up is due to this article from autospeed

http://autospeed.com/cms/title_Running- ... ticle.html

A VR ute owner swapped his injectors for smaller units and achieved a 9% reduction in fuel consumption without causing any issues to the engine.

i'm sure you can get a smaller injector, but there is an underlying issue you really should be fixing, if the fuel economy has gotten worse i would be fixing that before worrying about improving it.

from my experience there is only about 15-20% capacity head room on a standard injector, so it doesn't take long to have a smaller injector on its limits!

As above the factory injectors typically run at 80% duty cycle at WOT, so not much play left, really if you want to get the best, do some tuning and get it running in open loop at the afr you want, but really all that injector swapping for 0.3L/100km?? i can't see the point it'd only be measurement error margin anyway. Also he would have been in closed loop so all your doing in putting your fuel trims out but getting leaner highway due to smaller injectors. You can do this in the tune for less hassle than swapping injectors. Infact ive found upto 1L/100km improvement by going richer with lean cruise not leaner, have found lean cruise in commodores to be between 16-20:1 AFR in the factory tune.

As above if your babying the car and getting above 10L/100km or so id be looking at what problems you have, doing some datalogging and looking for issues.

Is the car modified in any way? What was the last thing that was done to the car before it started to develop this fuel consumption issue?

swapping the injectors wont help long term either because the car will use the fuel trims to slowly adjust it more or less back to original over time.

Faulty coolant sensor?
Faulty thermostat (stuck open)?
Wrong (lower than standard) temp thermostat?
All the above will give high fuel consumption.

The1 wrote:As above if your babying the car and getting above 10L/100km or so id be looking at what problems you have, doing some datalogging and looking for issues.

I think that will be my next path. But extremely inexperienced with this and will have to some research.

charlay86 wrote:Is the car modified in any way? What was the last thing that was done to the car before it started to develop this fuel consumption issue?

Car is completely stock, Nothing was done other than general servicing.

yoda69 wrote:Faulty coolant sensor?
Faulty thermostat (stuck open)?
Wrong (lower than standard) temp thermostat?
All the above will give high fuel consumption.

Next thing on the list will be changing the temp sensor. My mechanic has mentioned this as well.

When I've checked the coolant temp via the engineering mode it seems normal. Generally around the mid to high 90's degrees.

So what's my next step? Which data logging software is best for a novice?

- Dennis

why are you not happy with 10's?

so you should be getting 600K's out of a 60Litre tank, thats pretty good for an ecotec!

VX L67 Getrag wrote:why are you not happy with 10's?

so you should be getting 600K's out of a 60Litre tank, thats pretty good for an ecotec!

Unfortunately I'm not getting 10's, best i can get is 13's and having to drive like a Grandma....

My VX has the factory optioned faulty fuel gauge.

Normally i fill 65 Litres and get around the 410-420km mark.

So to achieve 13's i have to inconvience everyone else around me. To keep up with traffic the average is 15's

Have you cleaned your MAF?
Carby cleaner or contact cleaner will work ok.

A dirty MAF will over-report airflow and cause the ECM to over-calculate fuel.