Ok, this is confusing to me.

I have an auto ford au series 3. Straight gas but not factory.

I have been driving it for around a month and a half on economy and today I was disgusted when I refueled only to find I got 270 out of 66.5 ltrs.

I heard somewhere that one Taxis comp told their drivers to drive in third gear to boost economy. SO driving home I put it in third and drove at a speed of between 60-70kms. Normally what happens is when I fuel up the dte reads 420 then within two to five clicks city driving the dte drops to about 360 and seems to fall steadily but fast, till the car beeps at 80 left till dte. Also the fuel gage drops at the same rate. Gears in normal drive the best I'm getting is around 300kms with about 50 left on dte. THAT'S at best. Today I refueled. I drove all the way home in third and the car actually climbed in dte till I got home about 30kms later. It read 470 dte. I have never seen the dte that high. Plus the fuel bar hardly budged off full. Am I dreaming or is there a trick the taxi's know that most don't? How does this work? Also is it bad for the gear box. Surely someone here would know the reasoning behind this?

Tiffany

Being a taxi driver until recently I can tell you that we were told to drive in third gear unless doing over 70 k's

This, however was not for economy reasons.

We were told to drive in 3rd because it puts less strain on the trans and apparently in a taxi another 10,000 to 20,000k's out of a trans equals a lot of money saved.

I used to drive around in 4th anyway because I had to pay for the gas and an extra 30-40 k's out of a tank was better money in my pocket.

Although having said this a taxi averages about 250km's out of a tank of gas, more if it is factory fitted.

My fairlane (NA) duel fuel I get about 410kms out of a tank of gas around town.

I get 360-420 average round town
maybe 500+ on the highway once on a trip
a new HEGO sensor pushed my k's from 280 up.

Thanks you both for your replys.

I am baffled then as to why I seem to be getting better fuel eco.

Also I may look into a new oxy sensor as suggested.

Tiffany

Are you relying on the trip computer or actual klm from full to empty?

Basically When I refuel I divide the km's by the litres I needed to put in till full again. I have noticed a great change in amount of km's I have got so far. I will wait to see when I refill. I am wondering though, as I have an ex taxi, is it possible for the computer to be trained to use fuel according to previous driver. If so he may have driven in three and that is why the car reacts as it does to the normal drive gear....Ok might sound silly but just a thought.

Tiffany

I have an Xcab AU series 1 Tickford Duel Fuel and regularly see 400kays out of a tank around the burbs....

I would check/replace Oxy sensor also

disconnect the battery for 30 mins to reset the ECU

Would reseting the ecu change current fuel consumption for better or worse?

Resetting the ECU is best to do after making any changes. EG new sensors, leads, plugs etc. The engine takes 50 starts to relearn the settings for correct mixture etc or so I am told.

If you were to reset the ECU, it will relearn as you drive, so if you baby it, then it will be better on fuel.

I believe through logic I have worked out the problem but trying to get the gas guy where I live to understand my logic is proving difficult. He seems hell bent on running over everything and having a service. I am dubious though after trying to explain my theory that he knows what he is on about.

My theory is simple. The tank is NOT filling up the same amount each time. Simple. I fueled up today and it took only 40 litres to fill with having done 374.5 kms with 70 still on the dte. Now that is impossible. It is also impossible that on the last fuel I had to put in 66.7 litres which gave me 270.

I noticed on the one and only time I got over 350kms out of the tank, the tank was truly full with the red arrow way over the full mark. Today after it said it was full with only taking 40litres it was a little under full.

Put simply the car is not filling correctly. Now having said that, apart from a faulty float, what else could stop a gas tank filling all the way up. Yes I used the same bouser, at the same servo.

If anyone can tell me I am not crazy I will be over the moon. As the gas man thought I had left the planet and got annoyed. So me being feisty started to state my case with dignity but in a assertive way : )

Tiffany

you have more than one problem, you have to check replace o2 sensor as stated above,the plugs and leads-----check or replaced,timing checked and corrected.filler on gas tank can be checked by filling tank,then open boot and check the gauge on the tank,should read close to full--depends on how the tank lies in the boot.if you watch the filler flow it will be constant, unfortunately lpg is not the same,some are better than others,i found by trail and error that my cars like bp,shell,mobil -my first choice,most ks\ltr using the same method you use,trip meter vs ltrs,hope it helps, the rest is maintence costs,find a lpg mechanic that listens to you,i find girls get the run around,my girls come home with some very funny quotes that i cant work out.

i have a au3 dual fuel running a mega gas system,i get around 450k's on pwr and about 470ish on economy and thats using around 64L of gas no matter where i fill up,i don't take any notice of dte as its way out on gas but accurate on petrol,i always zero my speedo when i fill up so i know when its due to run out as the guage will show empty with about 150k's still in the tank.

2 things to replace that are simple and effective ... and hopefully should eliminate these issues:

HEGO sensor (it's always good to replace them over time as they do eventually fail ... sometimes they go out of range slightly or take longer to respond to changes).

LPG Gauge sender on your tank ... these are a common faulty item that does need replacing over time.