Sudden increase fuel consumption V6

[ExecVY]

My VY V6 wagon has suddenly had a around-town fuel consumption spike.

When driving in peak hour traffic exclusively, average speed around the 30s km/h, it never goes above 17.4l/100km - which it does often, as it usually is stuck in traffic. But that's the worst ever.

On holidays on the freeway, loaded up doing 110km/h, it'll do 9.2l/100km, and I'm sure I've seen high 8s once or twice on the computer when driving slower.

In town, when not peak hour, it'll get about 13-14l/100km average.

So I got a 120,00km service the other day, new plugs and filters, throttle body clean and injector cleaner put in, and now the consumption has shot up to 20.5l/100km around town! I did a trip on the M2 yesterday, reset the computer and for the M2 and the suburbs trip home its average was down to 9.2l/100km.

So it can do decent economy, but to me the performance seems down on what I thought it was capable of. It feels relatively gutless,tho cos I don't drive every day maybe that's just what its like.

Anyone experience these symptoms? Could it be a warm-up sensor failure? MAF sensor? I'm thinking idler pulley is out cos it still does okay for economy on an open road run

 

[andyman]

when you reset the computer all the time it will give you high readings due to the fact it is calculating more often to form the new average, which in your case is around town so expected,

if you leave it alone to do its thing, go for a few long distance touring, give it like 2-3000km to form a decent average to build up, the figure after that time will be pretty close to on the spot

 

[yeeros]

remember the gen 3 rattle saga????
well my VY, ever since new, i could hear a rattle in the engine coming from the lower half of the engine.
i think that since the engines are being exported to the desert countries, they are making the engines looser so they can cope with the heat (due to expansion and contraction). this in turn makes the engine prone to inefficiency, thus creating higher fuel consumption and lower power output.
the best experience with the 3.8L imo was in the VT. smooth torquey, quiet and fuel efficient under normal driving conditions.
since a rebuild is out of the question, all i can suggest is a piggyback computer and/or light supercharging (with a dyno tune), maybe a silent drive charger with no more than 4psi, thus not requiring an intercooler.

the biggest difference from vt to vy engines is the exhaust manifold. Im pretty sure the vt had 3 into 2 pipes where as vy has 3 into 1 before joining up at the firewall....correct me if im wrong.

 

[Raptorsc]

i think that since the engines are being exported to the desert countries, they are making the engines looser so they can cope with the heat (due to expansion and contraction). this in turn makes the engine prone to inefficiency, thus creating higher fuel consumption and lower power output.
the best experience with the 3.8L imo

No truth in that, all manufactured to same tolerance for all places

 

[yeeros]

absolutely. they make them all to the same standard, but there is a difference to the tightness from VT to VY.

 

[yeeros]

from what i know, the gen3 for example was built in canada, ie: cold climate, so all gen3's have a rattle...so to remedy this, they brought the gen 4 from mexico, with a similar climate to us...
I have stuck my head next to other vy's and they rattle too. Does the vx rattle seeing that its the same engine? my original vh bottom end is still quieter than the VY....

 

[BANKS]

from what i know, the gen3 for example was built in canada, ie: cold climate, so all gen3's have a rattle...so to remedy this, they brought the gen 4 from mexico, with a similar climate to us...
I have stuck my head next to other vy's and they rattle too. Does the vx rattle seeing that its the same engine? my original vh bottom end is still quieter than the VY....

never heard of anything like that before? who told you that?

 

[batemada]

get you idler pullys checked, i had a faulty one on my V6 VY and it was loading up my motor as if my A/C was on all the time even though my a/c wasnt on.

 

[nEb.]

its the government mate ... they're ripping you off from inside your engine lollll THEYR'RE EVERYWHERE!

 

[yeeros]

hahaha...... you said it nEb!!!!!!!!
BTW about the engines origins, I must have read it in some magazine, either street commodores or motor.......