Thread: Fuel economy 3.9 with O2 sensors

Thanks mate. What are you trying to get from the states and what's it for? What's the deal with the tune resistor? I have LPG fitted as well but as far as I know the fuel system is switched off on my install when I switch to LPG. The pump is switched off, injectors etc. What does the tune resistor change in the setup?

Cheers,
Peter

The tune resistor changes the fuel map. I guess they are to suit the different fuel qualities (and the oxygen sensors for US tune). Which would be interesting as my computer has had the fuelling chip altered by John Davis. So I don't know what happens with that.

The thing from the US is a code reader. Lets you know if you have any error codes and tells you what they are in a two digit format. Standard in US RRCs and I suppose Disco1s.

Ok, so the tune resistor shouldn't make a difference when going between the two fuel types. It comes into it in conjunction with the O2 sensors when running around on petrol. So, effectively you could put in the new tune resistance for the O2 fuel map and leave things at that, no need for switching.

There is most likely nothing to be gained from switching back to the Oz tune resistor when running on LPG.

I have the switch just in case. That case being either that there is an issue with the ECU enriching the mixture when on LPG and then running like a dog when switching back to petrol or that I want the extra power available on a open loop rich running system. Especially considering I most likely will lose the benefit of the John Davis remapped fuel map. I assume that is only available on the 180 ohm Oz tune.

I spoke to Bruce Davis once about what the remap did exactly and he couldn't tell me. Said it was done too long ago to know. So unfortunately I doubt they'd be able to tell me if the remap will work along with the oxygen sensors.
Plus now I can't find the invoice which had the info on it.

Utemad there is a mob in UK which makes new code readers but they rae GBP100 plus postage.
Products
But still you will have to add wires to your ECU unless yours has teh four pin plug.
Regards Philip A

Thanks Philip. I've seen that one but it is a lot more expensive again.

I'll see if I can find out what an American would pay if they just walked in to a wrecker (any Landy wrecker) as opposed to posting it to me. I have a couple of people over there that might be willing to help. I can't see them being that expensive 2nd hand if they are not prone to failure and were factory fitted.

OK an update.
I am currently in Quorn in the Flinders Ranges.
Fuel economy from Avoca Beach has been 16.5 L per 100km for the 2000 or so Kms.
Max has been about 105KMH but mostly at 100Kmh with a full load and 60 l of water and 2 jerries of fuel so the camper would be pushing 650-700KG .
Route was Avoca , Dubbo, Tarro -Darling nat park near Louth, down the Darling to Menindee ( E side with a million grids), Broken Hill, Quorn.
I reckon that is pretty good.
By the way have had next G all the way with High speed at Menindee, and I think 56 K here . Probably not much to be expected up the Stezlecki. BUT so far IMHO very good using my much maligned ZTE 252 as a modem.
Regards Philip A

Good to hear your results Philip.

Enjoy your trip too. We expect photos upon your return and lots of them