Thread: Where is my petrol going...?

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.

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

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

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

What you mean Willis? 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


Hope this helps.

Originally Posted by 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.

Sorry 'bout that Sam_d.

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.... 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

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

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 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

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).