My EF wagon has a straight gas conversion using a b2 converter, impco 225 mixer.
I also have a gastec fp30 closed loop controller.
I have made a custom coldair induction its picking up air from the FL wheel well with 3" pipe & a k&n pod.
I just fitted Ngk iridium plugs gapped at 0.8mm, new leads & new coilpack.
I originally had a feedback type air valve in the 225 and best I got was 18L/100. Usually 20-21L/100 around town, it was ridiculous.
I put in a standard stoich air valve and i'm now getting 16.5-17.0L/100.
Ive never done a trip with only highway driving to see what its getting.
I relocated the intake air temp sensor to down behind the headlight in the intake pipe before the mixer so the ecu sees colder temps and hopefully advances the timing a bit more.
what else could I do to try and getting a bit more out of it.
We average about 350-380km per tank 62L.
Ive got an APA A90 tank, capacity is supposed to be useable 72L. I found out the hard way and ran out, I could only put 68L in it.
I'll be satisified when I can get over 400 out of a tank.
Also, Ive checked the mixtures and they never getting richer than stoich so its pretty lean, especially at light throttle. the o2 sensor reads almost 0.
Would a better cam improve economy?
I still have the stocko exhaust, would 2.5" improve it?
im after any help i can get.

Extractors + a nice free flowing 2.5" mandrel bent exhaust will improve your economy. I added over 50kms to a tank with my car (details in sig below).

Is the car an auto?

I'd say a cam designed for lpg would also increase your power and economy.

I think that 16.5L/100kms on gas with city driving only is pretty good in a 4.0L Falcon, but with those few mods you should be able to drop it under 15L/100km comfortably.

can you show us a pic of how u fitted the 225 mixer, ive only seen 200s on EF/EL

also what is the feedback and stoich valve you are talking about???

I get up to 370-380klm with dual fuel about town no mods to the gas system etc.
I can get up to nearly 520klm on a country run.

extractors for sure, will make a noticeable difference, just don't go too big on the exhaust size, if your after full on economy even a 2" or 2 1/4" would be plenty.

I think that before you start modifying the car you need to work out what sort of economy is possible:

I have a late 98 model EL sedan that has been converted from auto to manual and back again.

With 200,000 k's with a 68L tank i got the following:
Granny driving:
Auto saw 480-530km's, this was 90% driving at 80kph+ for trips of 40km's at a time, very light throttle, lots of rolling but not stupid amounts.
Manual saw 430-450km's of country town driving (slowing down but not stopping at every corner etc).

What i noticed was, that the auto is around 15% better on the open roads, but the manual is alot better around town.

Aside from that, what i was getting at was the cars overall condition:
-Engines compression, spark plugs, leads, cap/coil pack, air filter etc.
I would not have used iridium plugs and i would definately gap them back to stock! They are leaning your mixtures out, you may run into problems like i did when using gaps too big- map sensor hose popping off etc.

-Keep things as stock as possible, the air intake is a good idea, although moving the o2 sensor - I dont think is a good idea, it reads the intake tempreture there so it can get the mixtures right.
Look at your intake piping, is it big and smooth enough, minimise the amount of piping (shortest distance means less resistance).
-Are you using a washable filter? Reducing your fuel usage isnt the only way to save money.

-Your style of driving is the first place to start, before you even think about opening the bonnet. If you leave 3-4minutes earlier than you need, you will eventually slow down alot.
-Take your foot off the accelerator half a block before the corner, less brake wear and less fuel is used.

I would not be replacing exhausts, cams, ecu's etc if you are chasing economy, unless they require replacing due to being faulty.
Apart from replacing the exhaust) when the time comes, all you can hope for is for nothing to go wrong.

Do you do the trick that brings up the "Instant Fuel Usage" and "L per 100km's" on your odometer?
-I dont know if it works on the EF's.

50% your fuel is used from 0-20, 30% from 20-50 and deminishingly so.
From start, roll as much as possible (without being a pest to other road users) Cruise on 70-80kph when you can, you use a lot less fuel.

Odds are you have an auto, flick the economy switch "OFF"
All the economy switch does it shift gears earlier and longer and retards your engines timing a little = worse economy, degraded transmission life etc. Vice versa for power mode, slightly better economy, longer transmission life, better shifts

Remember, auto's are great for economy on the open road and absolutely s**t around town, so minimise one and maximise the other and you will see another 100km's per tank depending.
Keep the spark plugs gapped right and air filter clean and thats all you can do, anything more is a waste of time and money, honestly.
-Remove any excess weight, dont remove the spare tyre (thats just asking for trouble!)

A lot of the time its not worth it, but you can remove the petrol system, this has two benefits, you remove about 30Kg's of weight and you can tune the car to run soley on lpg.

Last tip, its very pedantic, coming to a red light that might be a block or two away, back off early so you can keep your momentum up, so when the light goes green, you dont have to accelerate as much to get back upto speed. Easier to explain in person.

I have written an enormous document on economy and different ways to improve it in a practical sense, which i will post up oneday, but keep inmind that your better off using your energy for ways to make more money then you are using it to save money, because you will make more than you will save

*My two cents

Last edited by -GAS-MAN- on Wed Apr 23, 2008 12:07 am, edited 1 time in total.

Umm the stock exh is a 2 1/4 press bent item, so the only real upgrade is a 2.5" mandrel.

Yeah as LTD wrote, extractors are a good idea, give you an extra 50k's per tank and 2 1/4 inch exhaust is fine

A Tickford LPG ECU will make an improvement, read these:

http://www.fordmods.com/forums/viewtopic.php?t=31521
http://www.fordmods.com/forums/viewtopic.php?t=43709

Yeah but the only difference, apart from the label, is the tiniest advance in the ignition timing.

With such poor economy, start with trying to find whats causing it to run so poorly, dont try improving the rest until its doing 500km's per tank.

Does the car idle and drive smoothly? A vacuum leak maybe present..
Has your o2 sensor been replaced ? -This, along with the air filter and the plugs and leads are a main issue for lpg!

thanks for the advice gas-man.
i have a new o2 sensor, tickford gas ecu, i think it might be the cheap $29 filter from autobarn letting the rest of the system down. I need to replace it with a good k&n pod.

everywhere else I have read says smaller gaps for lpg not larger.
its probably a lot of my driving style more than anything. i like to go up to the speed limit quickly & smoothly most of the time in a hurry to get somewhere.

i fitted a colder thermostat today 71c, i'll see if it affects the economy or not.

Yeh im wanting more out of my lpg system 2, i get 330kms city driving but id me happy with 380-400kms but im lost of whats the problem with my system.

I'd doubt the el cheapo air filter will be restricting your intake, more like letting asmuch as the K&N through but not filtering out the dust and s**t.

I got told about the larger spark plug gaps by the gas fitter i used a while ago.
Yeah ALL of your fuel is used whilst accellerating, no joke, all of it!

What your doing is along all the lines of thought i was on 6months ago but never got around to doing, im very interested to see your results!
Kudos on all the work!

luke can you post up some pictures of your engine bay, I want to see how you have fitted the 225 mixer.

only ever seen 200's on EFs

[quote="-GAS-MAN-"].

A lot of the time its not worth it, but you can remove the petrol system, this has two benefits, you remove about 30Kg's of weight and you can tune the car to run soley on lpg.

I disagree with a small part of this statement, I recon always get rid of the petrol system, petrol and LPG are two quite different fuels, and even if you find a genius tuner , he will never be able to tune so both fuels are at 100%,It will always be a "compromise"tune( that's a polite word for crap ) between the two. cars usually get put on gas for economy, never ever going to get that 100% tune with petrol in there,Gas needs a colder plug, different gap, even a split timed cam,then you are starting to cook with gas!
trying to tune for petrol and lpg, is like trying(good luck) to tune an engine to run on diesel and steam, even if it runs,it will run like s**t.
That's mho,if I ever bought a dual fuel car, the petrol would be out of it in a week, then you can start tuning to make it get up and GO!
The rest of what gasman says is good info.
-I'm going to give tha increased tyre pressure a go, never thought about that, always just given them 32 all around.