Outer Limits 4x4 Board

just swapped the tired 3.5 for a 4l but am not happy with the fuel economy and wondering if its the setup or what ive got to put up with
Did a trip from Canberra to Orange and only got 24l/100km towing an 18ft poptop van home and got the stagering figures of 33l/100km and althis was in easy cruising mode not pedal to the floor mode.

Is this what i should expect or could i have a problem
all figures distances are from the GPS and was running 31"rubber and 4.1CWP which bring it back top almost standard.

Hi,
I've got an 95 3.9 auto Disco & get about 19-20 l/100kms
This is loaded with camping gear,also running 31's.

HTH
Steve

Seems like the 3.5 efi gear is not happy with the 4ltr.

Do you have a unichip to trim the fuelling. Yours is a hotwire so should be able to be tuned for better economy.
My 3.9 Rangie with unichip and free flow exhaust , with 245.75x16 (so 6% overgeared) gets about a true 14-15 l per 100Kms at 110 -115 Kmh.
regards Philip A

thanks guys looks like i may have a problem

thanks guys looks like i may have a problem

thanks guys looks like i may have a problem

suzidisco wrote:thanks guys looks like i may have a problem

You could say that again

Philip A wrote:Do you have a unichip to trim the fuelling. Yours is a hotwire so should be able to be tuned for better economy.
My 3.9 Rangie with unichip and free flow exhaust , with 245.75x16 (so 6% overgeared) gets about a true 14-15 l per 100Kms at 110 -115 Kmh.
regards Philip A

how much was the Uni chip and where did you get it done. Im fitting a 98Disco 3.9 to my rangie next week and wouldnt mind getting some better fuel economy out of it.

Fridgefreezer on this board has a fuel calculator for rover engines here http://www.juracid.co.uk/lr/v8fuelcalc.php

Ho Ho Ho :-) . really helpful. Yeah i was recently re reading an Australia $WD where the guy was saying that the 4 litre was much better than a 3.9 Que???

Graeme Cooper did mine . cost is $1400 +- including a new amplifier as the crap rangie one is incompatable. The Unichip has ignition mapping of a sort. its able to pull out advance selectively, so the vac advance is disconnected. Has ability for 2 maps for LPG and petrol also.
I am really happy with mine.
regards Philip A

what are the motec systems like are they better than unichips

Motec (like Haltech and MegaSquirt, etc) are ECU's.

The Unichip is either a piggyback ECU (designed to work in conjunction with the existing ECU) or a chip to replace the standard chip in the stock ECU.

Rangee has gone the Haltech route. I'm a little biased and would say Haltech beats Motec, although I haven't seen if Motec have 'lifted their game' over the last few years. Good thing is that these systems are fully programmable and use O2 sensors and dispose of that POS Lucas/Hitachi air flow meter.

Unichip is a piggyback chip which alters the inputs to the ECU to fool it into providing a better fuel map. it also has an ignition map as I said, so really updates a 14CUX to GEMS standard.
Just be aware that after market ECUs can get expensive to fit and program. A motec is about $2600 ? plus programming.
A Haltech is much cheaper but there is a LOT of dyno time to pay for if you want it to run 100%. and isn't that what you will buy it for?
I read recently that the GM ECU has 200 starting maps.
The 14 CUX has many nice things that you do not appreciate eg idle up on air con, MAF sensor, different strategies for hot fuel, cold fuel etc etc.
Even the unichip intros some quirks, eg when not hot not cold, when the temp guage is up but the oil thick, mine stalls going into drive now. I guess because they have leaned down a bit.
So , although many guys will tell you how good these things are , none will tell you the down side, eg stalling while cold, flat spots, etc etc. You learn to live with them, but its not factory type performance.
So thats why I chose a unichip.
I got about 15% extra over 3000RPm and under 2000RPM, and 11 % at peak torque, with unichip only.
Adding exhaust and free flow heads adds another 7% across the range.
The unichiop was the most BHP per dollar.
Regards Philip A

My 3.9 gets 7.7L/100k (4BD1 Diesel )