Where is my petrol going...?

[sam_d]

I'm getting really p!ss poor fuel economy again. Half a tank of petrol only got me 180km this week and that is after driving as conservatively as possible after only getting 320km on the whole tank last week.

I never expected 'good' fuel economy when I got my Disco but still thought something better than 25l/100km. :mad:

Given the following:
Tyres are a good pressure (not too soft).
Fuel not leaking from anywhere.
Conservative driving style.
Oh, and the handbrake isn't applied either!!

Any suggestions as to why this is so bad or how to get it better? I'm suspecting there might be a fault with my engine management - could this be possible?

If engine management is the problem is it worth replacing with one of those Unichip jobbies? Are they worth the money etc?

Cheers in advance!

[sclarke]

is someone milking your tank????

Mine gets Crap economy at about 22l/100km

Steve

[sam_d]

is someone milking your tank????

Mine gets Crap economy at about 22l/100km

Steve

Nope, nobody is stealing it - the needle remains in the same place between driving but moves like the rev counter needle once I'm driving... :(

[justinc]

Sam, Stick in a 88deg thermostat, replace the coolant temp sensor aswell, and run the ignition timing up to 9deg BTDC. While you have the cap off, check the rotor button moves back and forth against the mech advance weights, if the advance is siezed then the dizzy needs to come out and be freed up. That'll make a HUGE difference.

Try those for starters.

JC

[mcrover]

Ever considered the quality of the fuel your using, some ethanol blends burn heaps quicker than the standard old ULP or PULP.

That is extremely crappy economy though, even from a V8.

[sam_d]

justinc: I'm not that mechanically minded and while I do appreciate the reponse, it was all Greek to me! :)

mcrover: I'm using good old standard unleaded - nothing special. :(

[Pedro_The_Swift]

justinc: I'm not that mechanically minded and while I do appreciate the reponse, it was all Greek to me! :)

mcrover: I'm using good old standard unleaded - nothing special. :(


unless you have shares in a bank,,
I'd learn greek;)

[LandyAndy]

And Im plissed that my TD5 has dropped from 500ks at the 1/2 way mark to 325ks:eek::eek::eek:!!!!!!
We may both have faulty AFM meters!!!!
Andrew

[Quiggers]

Sam: I bought a new Disco V8 in 1995 in Sydney. After running it for about 5,000ks, I also wondered why I was getting only about 320ks from a tank...

Various service people said this was normal for city use.

Over its short life (55,000ks), a (city) tank would max at 350ks, (near on 80 litres) my many runs from Syd to Noosa would see a tank stretch to about 550-600...

shoved in 82 litres on one fill up, must've been running on vapours....

they drink...


footnote: currently, my out of tune and tired 3.5 V8 (291,000ks) is sucking it at 20 litres per hundred and thats country driving

there's a famous Land Rover specialist near you, get him to give it the once over.

cheers, GQ

[sam_d]

Sam: I bought a new Disco V8 in 1995 in Sydney. After running it for about 5,000ks, I also wondered why I was getting only about 320ks from a tank...

Various service people said this was normal for city use.

Over its short life (55,000ks), a (city) tank would max at 350ks, (near on 80 litres) my many runs from Syd to Noosa would see a tank stretch to about 550-600...

shoved in 82 litres on one fill up, must've been running on vapours....

they drink...


footnote: currently, my out of tune and tired 3.5 V8 (291,000ks) is sucking it at 20 litres per hundred and thats country driving

there's a famous Land Rover specialist near you, get him to give it the once over.

cheers, GQ

I don't do town driving really - well, not town driving as in the commute in and out of Sydney. My recent journies have been to places like Kuring Gai and the Royal National park so it has been mainly on the faster roads rather then battling city traffic.

I might take it up to that 'famous place' :) - I'll give them a second chance to have a look at it...

[lokka]

Sounds like it needs a good tune i get 15L/100 around town and beta out on the open road with a tired ol 4.4 in a rangie with a 4spd :D:D:D

[alc351]

If it Helps I have a sep 93 rangie 3.9l

Normal use (good mixture of hwy and town) is 19l/100km

Normal hwy use is 15l/100km up to 120km/h speeds(with some town work)

Ideal cruising @ 90-95 km'm can get below 12l/100km.

This is using Shell Optimax or now 'v-power'

I measure my fuel economy only by how many litres goes into the tank exactly, full tank to full tank, and have measured this over the odometer also for 40,000km's.

My car is totally standard (200,000kms) and still has the original exhaust system and intake, however, I have just purchased some HM headers and a K&N filter, will be fitting them within the next 2 weeks and are hoping for 5-15% better economy and power. If anyones interested I will post the results when I can.

[jimbo110]

When I bought my 3.9 Disco it was a heavy drinker. The problem was a faulty vacuum advance unit on the distributer.

[Safari]

I had the same proplem about 290 ks out of full tank, 96 V8 Disco, had the vacuum advance replaced and re chipped original ECU now get 450ks out of tank all up cost $700.00

Cheers

Rob

[4bee]

I'm using good old standard unleaded - nothing special.

What you mean Willis?:D 90 or 95 RON?

95 is the LR min rec.

Have you tried a dose of good Injector Cleaner as it could be rubbish spray pattern & fuel is being wasted?

I use Morey's Upper Cylinder Lubricant & Injector Cleaner after using a good cleaner.
http://www.derek.com.au/MOREY'S.html (http://www.derek.com.au/MOREY%27S.html)


Hope this helps. :D

[justinc]

justinc: I'm not that mechanically minded and while I do appreciate the reponse, it was all Greek to me! :)

mcrover: I'm using good old standard unleaded - nothing special. :(

Sorry 'bout that Sam_d.:o

1)The thermostat is crucial in a 14cux system(Yours) being that at cooler running temps the ECU thinks the engine is still warming up, and 'helps' by injecting more fuel as a 'choke' like function...:mad:. Operating temp for these engines is 88deg. The faster it gets there the better.
2)The coolant temp sensor is the unit that tells the ECU what temp the engine actually is. I have recently experienced one that had momentary open circuits and would cause the ECU to overfuel horrifically when it felt like it. About $55. for the part. You could use that much in extra fuel in a month if it is intermittently faulty.
3)The ignition advance factory spec is way too retarded for our fuel etc. Even with standard ULP you can run up to 9deg at idle, as these engines are low compression in aust.
4)If your Vacadvance or mech advance in the distributor are sticking/ not doing there thing, this will be a killer for fuel economy in a big way. Get someone who understands these engines to give it a good look over.

JC:D

[Grimace]

Mate i too am getting **** poor fuel economy out of my 91 3.9L.

So far I am flat out getting 120Klms (from 30L of premium). Ill be goin through this thread and ill inform you wat increases the economy to a respectable amount.

So far i can tell you that a cam and new timing chain and gear will increase the performance ten fold over a very worn set but didnt improve the fuel economy.

I am looking to reprog the ECU and check out the dizzy hopefully next week and ill report my findings.

Goodluck with your 3.9, keep me posted if you find anything.

Cheers
Grimace

[UncleHo]

G'day Folks :)

For those that are suffering from possible Diaphragm problems, it might be worth contacting Mike Bushnell, at Advance Diaphragm Options, they do metal canister diaphragm exchange, they can be contacted on (07)5428 0808 or www.advanceddiaphragmoptions.com (http://www.advanceddiaphragmoptions.com) that will get you the website:) he brings the gear in from O/Seas and realy knows what he's on about.

Justinc :) there might be some business advantages there ;)
N.B. I am not in any way commercialy connected with Advance Diaphragm Options.

cheers

[sam_d]

I've got me Disco booked in for Graeme Coopers to have a look at. :)

It sounds like there is far more to investigate and fix than I have time for / am competant to do myself. :(

It might be another expensive trip but at least it'll all be fixed properly I suppose (I'm hoping to have a more positive experience this time round anyway).

[dullbird]

I'm getting really p!ss poor fuel economy again. Half a tank of petrol only got me 180km this week and that is after driving as conservatively as possible after only getting 320km on the whole tank last week.

I never expected 'good' fuel economy when I got my Disco but still thought something better than 25l/100km. :mad:

Given the following:
Tyres are a good pressure (not too soft).
Fuel not leaking from anywhere.
Conservative driving style.
Oh, and the handbrake isn't applied either!!

Any suggestions as to why this is so bad or how to get it better? I'm suspecting there might be a fault with my engine management - could this be possible?

If engine management is the problem is it worth replacing with one of those Unichip jobbies? Are they worth the money etc?

Cheers in advance!


320 out of the tank last week pretty sure thats near what we get out of our v8

[sam_d]

320 out of the tank last week pretty sure thats near what we get out of our v8

Not good is it? Mine got much better than that when I first got it though. And it accelaerated much better. Etc...

I think it just needs a good look over.

[blitz]

hey Justinc

1)The thermostat is crucial in a 14cux system(Yours) being that at cooler running temps the ECU thinks the engine is still warming up, and 'helps' by injecting more fuel as a 'choke' like function...:angry:. Operating temp for these engines is 88deg. The faster it gets there the better.
2)The coolant temp sensor is the unit that tells the ECU what temp the engine actually is. I have recently experienced one that had momentary open circuits and would cause the ECU to overfuel horrifically when it felt like it. About $55. for the part. You could use that much in extra fuel in a month if it is intermittently faulty.

that sounds quite likely to be my problem as I know it constantly runs rich. Where can I get these parts?

Blythe

[billiardbrett1]

I have just posted this on another thread in this section, but go and buy a new fuel cap. You will be surprised just how much fuel dissappears due to evaporation. It will only cost about $30 and you will notice a difference. Mine improved about 20% overnight on a 97 Disco with an original fuel cap.
Brett