Another fuel consumption thread

[Disco95]

Hey guys, just wondering, I'v got a 3.9 V8 1995 Disco. Until recently I was doing an average of 16 - 18L per 100km. Almost all highway work, and mainly to work and back, 25km each way With some 4WD work and the odd towing job - maybe once a month towing a pretty decent load.
I cut the centre muffler out as it was knocking the chassis after some mild rock work one day. I replaced this with a straight piece of pipe.
Now immediately I noticed that the vehicle sounded REALLY good, which in turn meant that I started changing gears at about 4500rpm instead of 3000rpm.
My fuel consumption shot up to 19 - 20L per 100km.
after a few weeks I decided to ease offf and kept a good eye on the tacho. Going back to my sedate style of driving has made no difference. i'm still using 19 - 20L per 100km.
NOW...my first rweaction is to go back to my 4500rpm gear changes and the joy of a beautiful exhaust note, but, am I missing something? Shouldn't a free flowing exhaust improve my economy?

[DAMMAG]

I'm no expert but maybe it is on the lean side and therefore not as efficient. So you open the throttle and give it more O2 and it becomes MORE inefficient?

I am playing with the same issues on my D1 but have not had it long enough to work it out. Today I got scaringling (not a real word) good fuel economy on the highway but it dropped off around town which brought it back to normal. I was worried it was too lean.

I want to fit an exhaust sensor so I can see for myself.

Damian.

[4wd4fun]

Back when I had a 94 Update D1 3.9 V8 the dealer advance the timing and this improved resposivness and fuel economy, and another mechanic did the same to my EFI 3.5 V8 RRC. Noticed Fuel economy improvement.
But at least now my Disco felt like my dads 94 RRC 3.9 v8 as he used to leave me for dead.
The dealer on the Disco said they had been given new specks for tune after the car had done 20000km the auto worked better. I had it from New.
My mechanic on the RRC said to let him now if it startes to ping at all.
I dont know what they set the timing to other then it was advanced.
Hope this helps.
I now have TDI 300 does not sound the same at all but has been a great vehicle.
cheers Allan.