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Is my V6 VZ in need of attention?

peachey

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Holden VZ V6 AUTO Berlina Wagon
Hello all,

Im generally pretty savvy with cars and the working parts of them. but with things getting newer and more digital im not sure where to put my finger to fix it.

I owned a nice 5spd manual vy v6 storm ute before this vz wagon and i know that on the highway i averaged around 8-8.5L/100km and around town was between 11.5-14L/100km depending how hard i drove it.

i bought this vz a few months ago and fuel economy has been pretty average since (on the bad side)

it had a miss when i got it, and bought a basic diag tool (autel al319) to help find the isssue. it told me that O2 sensor issue post cat and left bank i think it was was lean at some point.

so instead of just going out and spending heaps of money on O2 sensors and crap i went through the extensive service history i managed to get a hold of and found the plugs hadnt been replaced for 80,000k's. so replaced then and miss was gone.

now back to fuel economy, when i drove from brisbane to cairns i was expecting decent L/km's the whole trip up, well under the 10L/100k. i didnt have much onboard and only had myself and 3yo in the back. over the whole trip i averaged about 12L/100km. which is really crap considering we did one overnight and stopped on the way for usual fuel and food.

now the lowest i managed to get was between townsville and cairns and it didn't drop below 10L/100km. around town im averaging around 16-20L/100km which is just rubbish. what should i do next? would this be causing by O2 sensors? or do these things need a "tune" once in a while? i didnt think they did since it was all automatic with the sensors etc.

the diag tool isn't posting any errors any more so i have nothing to work on.

any help or advice would be much appreciated. thanks ppl.
 

FirstVL

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I'm not an expert, but problems with the O2 sensor sound like a distinct possibility. From Holden VZ Commodore Recalls and Problems:
For models with V6 engines produced before October 2004, the left oxygen sensor wiring may fail due to its proximity to the exhaust manifold heat shield.
 

Tonner Matt

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Have heard that they are thirsty from several guys that own them. Have you replaced the fuel and air filters since you bought it ?
 

peachey

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its a 2006 model. so O2 sensor wiring might not be the issue? its not flicking errors so the O2 sensors aren't completely stuffed but not to say they aren't reading a little off and making it run rich?

fuel filter was replaced on the 15/10/2013, this would be making it lean cuz it would be starved of fuel yeh? or would that make car switch to safe mode and just throw more fuel at it? seems to lack power so that could be it?

air filter was replaced 1/2/2013 but looks like its been cleaned on each service 3-4 months apart according to service history.


P.S. this vz seems slow compared to my vy v6 storm which had 20kw less. bit gay. could be running in safe mode, but wouldnt that flick an error?
 

peachey

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anyone able to help?
 

Bundybear69

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change the o2 sensors, they #### out and there is no fixing them. change them out, do a service. when you pull them out the tips will probably be as black as the ace of spades from running to rich, when they #### up the computer cannot sense the afr and so adds more fuel to protect the engine. most of the time it will not read an error code even if they are rooted.
 
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