Realllll bad economy! HELP? :)

[shezza]

So my commodore is getting about 250 around town and 500k country driving.
Thing is... I drive it real easy. People driving lead footed are getting more :S
Car only has 60,000ks on it.
Just got it and the original owner was an old guy.
Car sat around for about half a year.
I would think the o2 sensor is quite young, so it wouldnt be the problem.
Any ideas would be appreciated.
Thanks

[wraith]

Check the error codes and see what comes up. If it sat around for a year and a half I would personally change leads, spark plugs and chuck some new oil in it.

[WogBoyz]

+1 id give it new oil, oil filter, plugs leads and new airfilter maybe even run a few tanks of 98 with an injector cleaner

[zskinner]

How young do you reckon the o2 sensor is? Cos anything over 30,000 kms and the o2 sensor can start deteriorating. I was getting about 17 litres per 100kms city driving and 10 litres per 100kms highway driving and when I changed the o2 sensor it went down to 13 litres city and 8 litres highway. Not saying its gonna be the problem in your case but definately dont rule it out ay. Good luck with it mate

[VT-565]

Sounds like you need to give it a service then take it to an off-street drag meet.
Flog the piss out of it.

[sik_dose]

Ive solved all my fuel economy issues by changing the O2 sensor, Fuel pressure reg, fuel filter and replacing all the breather lines on the fuel tank because they were totaly deteriorated. I get over 400km to the tank city driving (i just fill up around 400km have not tested it till empty)

[Brett_jjj]

I wouldnt rule out the oxygen sensor even if it has only done low km's.It might have corroded inside the pipe or it could just be a faulty one that is sending the wrong info to the ECU.. Id do the above mentioned full service on the engine,including the fuel and air filter, and also change the auto trans filter and fluid, if it is still bad on fuel after that,then Id be looking at replacing the oxygen sensor.Also try putting some injector cleaner in the fuel tank a few times when filling up..One more thing to check is for dragging brakes.The pad only has to touch the disc slightly if a caliper is seized up a bit and not retracting properly,and it will cause slight drag and increase fuel usage.

[LordMayhem]

is 13 to 13.5 per 100k's around town bad economy for a series 2 vn v6 calais?

[sik_dose]

I wouldnt rule out the oxygen sensor even if it has only done low km's.It might have corroded inside the pipe or it could just be a faulty one that is sending the wrong info to the ECU..Id do the above mentioned full service on the engine,including the fuel and air filter, and also change the auto trans filter and fluid, if it is still bad on fuel after that,then Id be looking at replacing the oxygen sensor.Also try putting some injector cleaner in the fuel tank a few times when filling up..One more thing to check is for dragging brakes.The pad only has to touch the disc slightly if a caliper is seized up a bit and not retracting properly,and it will cause slight drag and increase fuel usage.

how do you check for brake drag?

[Brett_jjj]

Just jack up each wheel and spin them by hand and take note how hard they are to turn,they should spin fairly easily with a bit of drag.If one is really hard to turn then it probably needs further inspection by removing the brake pads or caliper and then turn the wheel to see if it turns freely now.Remember the rear wheels will be turning the diff and tail shaft so will be a bit harder to turn.But you will definitely notice if one of the calipers is stuck on a bit.If you do find one is seized,then its best to replace or service the calipers as a pair,either both front calipers or both rear calipers .

[WogBoyz]

also check typre pressure

[zskinner]

is 13 to 13.5 per 100k's around town bad economy for a series 2 vn v6 calais?

lol a bit off the topic but yer thats quite good. my vp gets about 13.5 - 14 around town and my mates vn series 1 gets around the 14 - 14.5 (and considering your calais model is a heavier car than the standard executive model that makes your fuel economy even better)

[LordMayhem]

cool thanks my o2 sensor must be ok then. was just wondering sorry for the hijack

[shezza]

Thanks for all the replies guys.
I think I will get onto the o2 sensors first.
Anyone know how many ohm I am looking for? Can it only be tested cold?

Cheers