GU TB45 Wagon on LPG

[fmacdonald]

G'day

I feel I have read as much as I can and still not sure if my mileage / performance is correct :1087:. The wagon has just been service and have swapped the 33'' back to factory tyres and still getting 32l/100km around town.

The car is an LPG TB45 with auto and roof rack, should I be looking further into the fuel economy?

I am considering buying a wideband o2 sensor and gauge to give tuning a go myself?

Should I be worried and if so what should I be checking?

Cheers

Faulkner

[YNOT]

That fuel consumption does seem excessive, even for a TB45 with a roof rack, is that consumption figure on LPG?

It could be caused by many things and there may be several factors contributing to it. Valve clearance, ignition timing and general ignition system condition, air filter condition, vacuum leaks in the inlet, partially blocked exhaust etc. Even things like air flow meter, exhaust oxygen sensor and coolant temperature sensor can be working within range that they won't log a fault code but are not sending correct signals to the ECU. Trial and error but start with the basics and cheap stuff first.

[fmacdonald]

Cheers YNOT ... I know the leads, plugs and filters are new. The consumptions is for LPG, I am going to try driving it on petrol next week and compare the difference.

[threedogs]

You need BOB , he recently posted his fuel figures on gas and petrol.
Check in the search engine, bob's on the banks of the Murray ATM
contemplating all of lifes woes and solving some no doubt

Gas wise I'm thinking 350k plus a tank would be ok
on Petrol any thing from 20/100 to 25/100 and up.
Wouldn't think you would do better than that IMO

Just read the other thread seems the injectors were U/S and free wheeling hubs were locked in

[lhurley]

I get about 24l/100 on gas and petrol. I don't really baby it, but I don't flog it either. That's half city half high way too.

Where abouts are you mate?? I have a really good gas guy here in Brisbane.

[fmacdonald]

thanks for your help guys, I was not after a debate on fuel economy, just to work out if I need to investigate it further or just accept it is a TB45 :)

[threedogs]

How many Ks do you get on gas and how big is your gas tank.

[nissannewby]

thanks for your help guys, I was not after a debate on fuel economy, just to work out if I need to investigate it further or just accept it is a TB45 :)

Yes you can get better. You can try things like timing, valve clearances, tps settings etc. with your setup you should be able to get low to mid 20's/100

[fmacdonald]

Based in north west Sydney, pity

[fmacdonald]

I have a 90l tank, but put 71L in after 218km

[fmacdonald]

Does anyone happen to know how mechanics tune LPG? Do they use a wideband air/fuel meter or Carbon Monoxide meter?

[Bob]

I have a 98 4.5 GU on dual fuel which is tuned by a LPG specialist in Bendigo and cruising on a highway it achieves 18 Litres per 100 K's and 22/24 Litres per 100 K's towing my Jayco Dove.
Not sure of City Driving as I am from the Country and do not do much City Driving.

Stock Standard with Road Tyres. No Lift & No Roof Rack
I usually cruise at between 95 to 110 Kph.

My advice is to take your vehicle to a LPG specialist for tuning

[fmacdonald]

Thank you Bob, just not had much luck finding a good one in north west Sydney.

[Evo]

Hi mate,

I have a 4.5 on petrol/gas, has 33's, full steel roof cage, tool box in rear, 80l petrol tank, 90l gas tank.
I get about 22-23l/100 on gas. About 1l more on petrol.

Evo

[NP99]

I'm getting about 23/100 on LPG.

[fmacdonald]

Great, gives me hope :)

[Lowie]

26-27/100 on gas, 22-24 on petrol me. But she's done 350K.
I figure it's a big truck so thirst comes with the territory. On the other hand I could always drive my missu's Civic but someone might see me...:-)

[Alitis007]

My 4.5 is straight petrol and i get 13 to 17l/100. I do 120km a day, 90km on the hwy but 45 of those k's in congestion in the mornings and 15km thru school traffic and 3 school zones. Hopefully i can get better fuel consumption with a couple of mods.

[fmacdonald]

My 4.5 is straight petrol and i get 13 to 17l/100. I do 120km a day, 90km on the hwy but 45 of those k's in congestion in the mornings and 15km thru school traffic and 3 school zones. Hopefully i can get better fuel consumption with a couple of mods.

What mods are you looking to make?

An update, petrol is 22l/100 and gas is 32l/100 on the same trip (daily drive) so it sounds like my gas is the issue?

[Alitis007]

What mods are you looking to make?

An update, petrol is 22l/100 and gas is 32l/100 on the same trip (daily drive) so it sounds like my gas is the issue?

Snorkel and exhaust for now.

[tricksgonefishing]

Food for thought, I have a 98 GU TI duel fuel and I wanted to fit a duel battery so I chucked out all the factory air box and shit and made a s/s 3" snorkle with a scoop across the top of the windscreen that has a narrow panel filter in it (the same as the ones used on V8 holden OTR intakes) and now I get a lot better fuel ecconomy on petrol but on gas it stalls every time I back off the throttle to coast up to a corner. I put a vac/pressure diagnosic gauge on the intake duct next to the gas mixer and at 30km/hr with my foot off the go pedal it was showing +0.12 bar and I think that pressure is upsetting the LPG flow.

[twisty]

on gas it stalls every time I back off the throttle to coast up to a corner.

I had the same problem. Slowing to a corner engine leans out and stalls. Fixed it by turning the snorkel inlet to face backwards. Not so easy for you.

25+ city/highway, 90 litres useable lpg (115l tank). 2" lift, standard AT tyres, alloy rack, no drawers or other heavy objects (water etc). I've seen 3 different (and recommended) lpg specialists, valves done regularly, new condensor, plugs, leads etc. Always the same economy for the last 3 years.

[fmacdonald]

getting the car tuned tomorrow so I am hoping for some magic :)

[twisty]

getting the car tuned tomorrow so I am hoping for some magic :)

Hogwarts lpg specialist?

good luck. curious to know what you get done.

[Bmak]

Food for thought, I have a 98 GU TI duel fuel and I wanted to fit a duel battery so I chucked out all the factory air box and shit and made a s/s 3" snorkle with a scoop across the top of the windscreen that has a narrow panel filter in it (the same as the ones used on V8 holden OTR intakes) and now I get a lot better fuel ecconomy on petrol but on gas it stalls every time I back off the throttle to coast up to a corner. I put a vac/pressure diagnosic gauge on the intake duct next to the gas mixer and at 30km/hr with my foot off the go pedal it was showing +0.12 bar and I think that pressure is upsetting the LPG flow.

Depending on the setup you can connect a balance pipe back to the converter top stop this happening.

[fmacdonald]

The 4x4 place I went to checked the valves, filter, leads, plugs and advanced the timing. They suggested the plug I am using are not ideal but did not expect there to be any impact. Not expecting any change but will know after the next fuel fill up. If no luck I will go to "The Gas Man" in Seven Hills, NSW. Anyone used them?

[fmacdonald]

Now running at 30l/100km ... have pointed the snorkel backwards ... expecting no difference but what harm can it do :)

[lhurley]

Now running at 30l/100km ... have pointed the snorkel backwards ... expecting no difference but what harm can it do :)

Should be able to get it lower then that. I drove mine from brisbane to melb and back and got in down to 17L/100km. Reset everything (disconnect battery) and then take it for a long drive. Obviously not a 4000km drive but something to get it to relearn properly.

[threedogs]

How did you figure out the 32/100 k part, that's like 300k a 90 ltr tank on ULP

[fmacdonald]

Quote "Should be able to get it lower then that. I drove mine from brisbane to melb and back and got in down to 17L/100km. Reset everything (disconnect battery) and then take it for a long drive. Obviously not a 4000km drive but something to get it to relearn properly."
I will give this a go this weekend :)


How did you figure out the 32/100 k part, that's like 300k a 90 ltr tank on ULP

I typically fill up at 250kms however I just fill up each time and work out the L by the km driven, eg last week I filled up and got 74.8l with 249km travelled.

[fmacdonald]

Should be able to get it lower then that. I drove mine from brisbane to melb and back and got in down to 17L/100km. Reset everything (disconnect battery) and then take it for a long drive. Obviously not a 4000km drive but something to get it to relearn properly.
Just thinking, would this make a difference with LPG as it is a separate unit ? Still a good idea as costs nothing.

[threedogs]

Not sure about the re-learn bit but it may re-set some errors.
Shoot Bob a PM he has a well set up 4.5 returning good figures

[lhurley]

Just thinking, would this make a difference with LPG as it is a separate unit ? Still a good idea as costs nothing.

Depends on your LPG system. I would assume newer units can self learn

[snakey1989]

Hey, with lpg stalling and having a snorkel fitted, a balance pipe is a MUST to keep fuel ratios right... This is a problem for ALL lpg powered 4wd's with snorkels or cold air intakes.

[snakey1989]

Oh and for the record, as a mechanic myself, LPG is VERY easy to tune. (Well gas mixers are, not LPG injection)
All you need to do is find where the idle and max output adjustments are - for example I have an IMPCO 300A (on a GQ tb42) and the idle mixture is in the top of the mixer and the max flow is on the side. Once the idle mixture is set correctly, the rest should nearly sort itself as the max flow adjustments only really govern foot near the floor consumption.
Seriously, anyone with a little bit of knowledge can easily tune LPG, but if you have NO IDEA, don't play with it. Anyone in the Snowy Mtns region can come and see me or Dad, we know LPG back to front and inside out. I just LOVE the stuff!

[Evo]

Hey, with lpg stalling and having a snorkel fitted, a balance pipe is a MUST to keep fuel ratios right... This is a problem for ALL lpg powered 4wd's with snorkels or cold air intakes.

I was talking to someone about this.
Apparently if the car has a maf and it is still used, the stalling issue is eliminated.
Please clarify if there is something else?

Evo

[NP99]

Quote "Should be able to get it lower then that. I drove mine from brisbane to melb and back and got in down to 17L/100km. Reset everything (disconnect battery) and then take it for a long drive. Obviously not a 4000km drive but something to get it to relearn properly."
I will give this a go this weekend :)



I typically fill up at 250kms however I just fill up each time and work out the L by the km driven, eg last week I filled up and got 74.8l with 249km travelled.

I think there's a lot of poor quality LPG out there too. The mix blend changes depending on how and where they source it. Avoid BP gas it clogs your filters early with oil.

[twisty]

Hey, with lpg stalling and having a snorkel fitted, a balance pipe is a MUST to keep fuel ratios right... This is a problem for ALL lpg powered 4wd's with snorkels or cold air intakes.

I haven't got a balance pipe, I don't think... Is this where it would go?

34196

[lhurley]

Mine connects to either side of the maf

[twisty]

Mine connects to either side of the maf

Huh? Like this?

34205

Any one else care to share lpg setup photos? I'm a visual learner ...

[lhurley]

Huh? Like this?

34205

Any one else care to share lpg setup photos? I'm a visual learner ...

Yep that it essentially. Not sure how right it is, but it's worked since I've had a snorkel on. The idea of the balance pipe is to remove some of the positive pressure caused by the snorkel having a ram air effect

My pipe goes from just after the maf to just before the air filter as it was easier to drill the plastic then the metal. I can take a pic tomorrow if need be.

[twisty]

I can take a pic tomorrow if need be.

Thanks, that would be good. Not needed but much appreciated.

[NP99]

Good pic to have, my snorkel will be going on soon.

[Darian]

G'day All,

I realise this is an old thread, but really need some advice on this topic.

Have a 1999 GU Wagon 4.5Lt Auto on Petrol / Gas.

Gas System is Injected (Zavoli), so starts on Petrol, then once warming up and revs are right switches to gas seemlessly.

I've had the vehicle for about 8 years now (bought it off a Mate at a really good price), but the economy is really shitty.

Used as daily driver / work and mostly around town/city with some country runs, serviced regularly every 7500 - 10000Km.

Around town, pulling the tandem trailer or not, and no difference between Petrol and LPG Consumption, I use 30L/100Km!! 90 Litre Usable LPG Tank.

Between starting and warming up on Petrol and switching to LPG, get around 320 km per fill and top up of both tanks, varies very little, maybe by 10km or so.

Country / Highway runs are slightly better, averaging around 25-26L/100Km.

Have had it tuned and double-checked numerous times, cleaned the MAF Sensor, replaced the Oxy Sensor all with no noticeable difference.

Was thinking of trying the Headers and Exhaust option to see if that improves it, even ever so slightly.

I realise that it's a lump of a vehicle, and not expecting to run the quarter mile, just looking to improve fuel economy and increase power a little (is very sluggish when it sees an incline).

One thought is a LS2, but trying to exhaust (pun intended) other options first.

Any help, thoughts and assistance would be greatly appreciated.

Cheers,

Darian - Adelaide.