Poor Fuel Economy (VN Series 1)

[Tibokan]

I know that this question has been asked before, but there hasnt been a definitive answer. I get 300-350 on a full 63L tank around the city in my VN and it seems quite bad compared to others peoples VNs. Is there something wrong with my VN and if there is, what would it be and how much does it cost to replace those items (from a wreckers)?

[Morton]

There isn't a definitive answer, because there never is Usually it's a whole bunch of worn out parts all doing a lousy job and contributing to bad economy. It's very rarely one thing. These cars are getting old, and various parts start contributing to poor economy - this includes, but is not limited to:

- worn oxy sensor
- worn coolant temp sensor
- clogged injectors
- worn spark plugs
- worn spark leads
- low tyre pressure
- clogged air filter
- worn fuel pressure regulator
- heavy right foot

350km around the city out of a 63L tank, means you're using 55L of fuel, which equates to around 15l/100 which isn't spectacularly bad economy for city driving. You can do a lot better though - I get 13l/100 out of my V8 in city driving. 12.3/100 if mixed up with some highway at an average speed of 45, so you've got room to improve.

I would start off with a service, changing all the stuff you can't remember replacing -

oil (15w50 or similar), spark plugs, spark leads (cheapest at supercheap), oxy sensor (on the passenger side extractor, $50 or thereabouts), coolant temp sensor and sender (both behind the alternator, $12 each), air filter, oil filter, fuel filter (located over your rear RHS axle). Then run a full tank of premium with injector cleaner, pump the tyres up to 38psi, drive like a grandma, and see how you go for that tank

[TVR-190]

bout the same as what my lexcen got, my calais gets about 400-450BEST

[peter65]

15l/100km is not too bad considering all of the above. i used to get 12l/100km out of my vp v6 auto running premium ULP around town and driven very gently.... pete

[Man]

Mortons advice is the go, 7 of 9 things he mentions you could check yourself, if it still has a drinking problem then best to get the mechanic to check the fuel reg and the injectors rather than fork out for labour u could do yourself, be sure to let them know of the things u checked so they dont rob u.