Weird Fuel Problem

[VLishes]

Ok, I purchased my car about 1 1/2 months ago, out of a tank of fuel I got around 410k's, this car wasn't serviced since Dec 04 so it missed a service and it was due for one, when I got my car serviced except for the air filter it had Bosch plugs which looked terrible, the oil was black, had my oil and fuel filter replaced and chucked in NGK plugs, strangley after that I only got around 330 out of a tank so I thought fair enough I'll give it another chance, maybe it was that week of driving, then the next week I got similar amount of k's.

I then purchased a CAI and noticed the filter was black, I didn't bother replacing it because I was getting a K&N filter, I felt a difference with the CAI on, little more responsive and fuel economy went up to 350~, a week later I purchased the filter and today the max k's I got was around 370~.

My question is, wtf is going on? could it be the plugs I'm using? don't know what else it could be, I thought of getting my favourite plugs again, the NGK V Grooves.

 

[sixshooter]

Done a paperclip diagnostic check yet?

 

[Scooter79]

Ok, I purchased my car about 1 1/2 months ago, out of a tank of fuel I got around 410k's, this car wasn't serviced since Dec 04 so it missed a service and it was due for one, when I got my car serviced except for the air filter it had Bosch plugs which looked terrible, the oil was black, had my oil and fuel filter replaced and chucked in NGK plugs, strangley after that I only got around 330 out of a tank so I thought fair enough I'll give it another chance, maybe it was that week of driving, then the next week I got similar amount of k's.

I then purchased a CAI and noticed the filter was black, I didn't bother replacing it because I was getting a K&N filter, I felt a difference with the CAI on, little more responsive and fuel economy went up to 350~, a week later I purchased the filter and today the max k's I got was around 370~.

My question is, wtf is going on? could it be the plugs I'm using? don't know what else it could be, I thought of getting my favourite plugs again, the NGK V Grooves.

One week you might get 330k's another 350, annother 370k's... You cannont judge a cars fuel economy just because of a variation of 20km's or so. One week you might have done one or two extra trips to the local shops, the other week you might have done some distance driving and avoided traffic lights. What about your driving style? Do you floor it at lights? Where is most of the driving done, in the city with lots of traffic lights and slow traffic or on an open road? My vs exec gets about 380k's to the point where the fuel light comes on driving around town and city in peakhour traffic. However in January I did a trip down to victoria from Sydney. I got to Wangaratta, a distance of 633k's and only used 51 litres. ...and a my CAI doesnt do anything for the economy. All it does is give you slightly better throttle response.

Read this post I made last month... http://forums.justcommodores.com.au/showthread.php?t=25082&highlight=fuel+consumption

 

[VLishes]

Yes I know 20k's ain't much but from 410 to 350 is a big difference, I don't push the car, tho I am use to driving it now and I find it peculiar that k's would suddenly drop that much after servicing the car. I drive to city everyday 5 x days a week then drive in the burbs on the w/ends, I understand that everyweek is different.