Diesel-Gas and Fuel Mix Adjustment

[OMan]

G'Day All,

I installed a dieselgas system about a year ago. My car is a Patrol GQ 1990 TD42 with a Safari aftermarket Turbo with 350,000KM and going strong. Does anyone knows after the installation of dieselgas system, do I need to adjust the fuel mix? Sometimes if I accelerate it hard, I get some black heavy smoke. Also at times black dust comes out from the exhaust.

Thanks.

[Patrolling Paddy]

I am guessing that with the aftermarket turbo and being a 90 GQ you don't have a boost compensator for the fuel pump. What sort of boost are you running? Who set up your turbo and have any changes been made since? Who set up the gas?

I think that you will find that accelarating hard will create black smoke regardless, however what I would suggest is happening is that when you stand on it you get max fuel instantly (due to no boost compensator) and the engine and gas then have to play catchup and wait for the boost to get there too. I would also guess that if you drive more sedately that you get little or no black smoke.

I wouldn't stress about it too much, mine is a 94 GQ with a/m turbo, I/C, gas and now about 14psi with no boost compensator and under heavy accelaration creates a black smoke screen, but under lighter driving make little to no smoke.

It is just a matter of driving accordingly, you will also find (if you keep records) that you gas percentage goes south when you drive heavy cause without the boost compensator you are pumping lots of diesel before the system has time to react and catch up, under heavy driving my gas percentages drop to around 16-17% and on highway and lighter driving I get 20-21% and a better overall economy too.

Hope this is helpful

PP

[OMan]

The turbo is running at 12psi and not modification to the engine has been done since then. I don't think it has a boost compensator. I am not really concern of some black smoke coming up when accelerating hard, since it is a diesel thing, and as you said it is because over fuelling. I am a little concern is that I leave a black mark in ground with a lot of black power from the diesel. Also at night I can see smoke when taking off (no hard taking off); my fuel economy is not as good as pre-turbo; although the car is 200-400kg heavier now due to winch, roofrack, lift suspension etc!

The LPG is supposed to clean up the engine, since I have not done more than 20,000 km yet with dieselgas system, it may be still in the cleaning up all the dirt from the engine. Did you find the same with yours? What LPG system are you running?

Thanks.

[scooby]

I have Dieselgas on a Hilux 3litre n/a. I have been told by the installer that too much gas causes black smoke and detonation. I did a fuel check by filling both gas and diesel tanks and driving a few hundred klms, refilling and working out the percentage of gas used. The first check indicated 50% gas to diesel, way too much. I was told optimum gas is around 23%.
I had the installer reduce the gas jet size and checked again. This time gas use was 36% so back again to try smaller jets. I don't have any more results yet but will have in a few hunded klm.
This set up seems a bit hit and miss to me. I would have thought there is some type of gas analizer that can measure the exhaust and indicate correct gas ratios.
Scooby

[OMan]

When I install mine, the installer asked me if I want performance, or economy. I pick the medium one. It is about 20%. For every 10lts combined, I used 8 diesel and 2 LPG. The percentage also depends on the type of driving. In sand driving I use much more LPG than hill or off road driving. Normally, 28lt of LPG last me around the 650km. During sand driving (Moreton Island), it lasted around 400km (300km driving in soft sand).

[dakar61]

Some good observations there PP and I agree with what you are saying, but we have seen a few diesel-gassed vehicles that have begun to blow lots of black smoke immediately after the system was fitted and "tuned".

They are then sent to us because they assume that it is a fuel injection issue. We do the blatantly obvious thing and turn the gas off and then do a smoke check and no more excessive smoke and more importantly no more detonation. So we send them back to get the gas turned down.

For anyone with diesel gas, be warned; if its blowing more black smoke, thats one thing and not really good, long term, but if its detonating thats another thing completely and lots of engine damage can occur, quickly.

By the time you hear the detonation knock the inaudible detonation that occurs just prior is already doing piston crown damage.

[Patrolling Paddy]

I just had mine dyno'd the other day and the air/fuel ratio was about 17/18 under load and about 28/29 cuising (I would need to have another look at the sheets to confirm) and apparently this is good/ok. We also checked with the gas off and from memory is was very similar (again have to check).
We also added about 2psi boost and a mickey hair on the diesel and this controlled the egts better too.

The black smoke has a high level of particulates (solids) and this is why the newer diesel are running the DPF systems on the exhaust, and this is more than likey also why you are seeing the black powder on the ground (I assume if you give it a belly full in the driveway or something?).

One thing you could do to put your mind at ease is go and have a dyno run done and check that it is all running as it should. If you ring around you should be able to find someone that has experience with dieselgas systems and with the dyno configured to suit you can get all the info you need to make sure it is performing well. It cost me about $230 for a run and tune and I was on it for about 2 hrs so not bad value really.

What sort of fuel figures are you getting with dieselgas? I am about 15L/100 combined.

PP

[swagman_64]

have a 5le rebuilt at 170k axt turbo diesal gas aust kit. gas is good but what it did was aid the motor to hold its head up for longer at higher rpm = speed=higher egts punting over hilly windy road at night the oil light came on & i shut it down damage was burnt glow plug tips through the turbo stuffed seals,& the motor oil went out the exaust in sympathy. many dollars later same system BUT pyro & boost gauges fitted. now the fun the turbo was fitted with a piggy back instead of setting the pump(5le 2 settings turbo or not)rebuild had the pump set put it to the dyno & got 124kw at the wheels then we rediscoverd the piggyback set it to 1 base setting & fitted a denco after destroying a set of gloplugs at 8000 km NOW hard pushed to get 500 on the pyro unless we wind the piggyback(only adjusts fuel but therefore ups boostcos the mix is more dence i think) blows a truckload of soot at 5 but not at 4(origonal dyno setting)gives 145 kw@ 5 114kw @1 still not bad fof a factory motor that gave 90kw flywheel standard. 24percent gass no dif to temp on or off . best advice fit quality guages VDO boost and more importantly pyro use gears rather than boost keep your temps down(same as in a truck)all should be good.

[OMan]

PP, I am getting 12-12.5 lt/100 in everyday driving with very little 4wd. 14 to 15 lt/100 with 40 to 50% off-road. I keep a spreadsheet with all my stats, so these numbers are real.


Some extra information: I also have a pyrometer and boost gauge. Normal operation I get between is 95 on idle, 200 in normal driving, and 450 when I take the car over 3000 rpms. My turbo boost is 12 max, and on highway driving stays just over 5psi.


I only get black smoke as you said if I belly it in the driveway or if I take off like a quarter of mile race. It does not happen in normal driving condition.

What is DTF?

I am thinking to take the car to the Taipen XP in the Gold Coast. They are one of the few with experience with diesel-gas dyno tuning.

[HDJ105]

What is DTF?


DPF = Diesel Particulate Filter

[Patrolling Paddy]

Not sure of who to go to but if Taipen have a good rep then I would be going and doing a run if for nothing more than peice of mind that all is well.

Let us know how it goes

PP