Thread: 97 disco 3.9ltr tuning

Being efi there is no real tuning apart from checking that evrything is working properly and in good condition. Chipping probably wont give better economy as you will use the extra power- 20/100 aorund town, i thought that was normal for a V8 disco ?

I think you'll find that the 3.9 in it's natural state will give you the best compremise in terms of both economy and performance.
A lean running V8 will start to run hot......a hot runner can contribute to a lapse in perormance...etc etc.
With 222,000km under the hood you can be sure that the injectors are in need of a cleanout. There are fuel additives for this purpose but nothing cleans injectors better than removing them and getting them serviced or cleaned ultrasonicaly.

I wouldn't bother with chips or mods to the ECU.....the price of a chip would take a long time to recouporate against any fuel savings.

Or..... go Megasquirt injection.....that way you can fine tune the ECU to your way of driving!

20lt per 100k in urban driveing is normal specs recon 19.5, mine was doinig 20lt per 100km urban 16.7 motoway conditions @100 kph cruise set on long trips seems to be the best.I don't tow that often but have cargo area sett up with double sett of draws with all the gear porta gas,bbq and recovery gear stowed away. So ready to roll at a moments notice.all the gear onboard is like haveing 2 extra people on board all the time.

Originally Posted by disco97

hey guys
i have a 97 disco 3.9ltr v8i which blows no smoke (222000kms) and runs great never had a miss but im using around 20ltrs/ 100km for running around town and a bit of highway. i would like to know if you can chip the 4by to make it quicker and cheaper to run like the td5 or is it a case of new exhuast and a dyno tune?. its only really a weekend car and towing about 2.5tonne boat so i want that bit more power and if i can get less fuel usage would be lovely.

20l/ 100 klms - that's about par, if not better for the course for a 3.9 auto around town

Graham Cooper's do a Unichip upgrade and Dyno tune which lifts power and economy - only problem is that it costs about $1500!

You can try resetting timing to 12 BTDC [ but make sure dizzy is in good condition and mechanical and vacuum advance is all working correctly!]...... and then running only on 98 RON petrol.....I find it gives a bit better power, responsiveness etc and a bit better economy, even with the usually 10c per litre extra cost of the high octane premium grade fuel.


BTW - don't bother with the changed specs timing if you want to use E10 [or whatever] high(er) octane ethanol blended petrol - although octane rating is always higher for an ethanol-blended fuel, the available energy [kilojoules per kilo or litre] is less and you'll notice a drop-off in power etc and a comensurate slight drop in actual fuel economy [litres per 100 klms] although economy in terms of cost of moving vehicle any given distance [$"x" per 100 klms] is roughly unchanged.

I had what I call a skitzophrenic brain to the EFI discovery.. if you kept it off full noise it ran the engine at about 1/2 max hit the Wide open throttle sensor and it would dump fuel as hard as the injectors would allow untill I hit the brake pedal.

for sydney I thought it was an ideal solution.. and got my city cycle down to about 12l/100k But she moved like a series firing on 2 cylnders... but when I needed it I had the original fuel map.

have you guys checked the vacuum advance unit on the dizzy....?
if its faulty it throws the fuel economy out the exhaust......

I get 20/100 running my 96 Disco 5 spd on LPG, cheaper running costs, little bit of power lack though .

thanks guys i was just not sure if i could get better or not, now i know that its not worth it.


jeff