car running on LPG : question

[sunny747]

Hello All,

my car runs smooth on LPG. But it's been a while since i drove my car on fuel . i have automatic LPG system which means the car starts on fuel.

however, i'm noticing when i fully drive on fuel the acceleration is not getting the force like it used to and it is cluttering a bit. The moment i switch to LPG, it runs very smooth and picks up very well.

before taking to garage, it would be great if i have some idea about the problem otherwise they will just rip me off. i assume it is some dirt.

any suggestion would be appreciable.

thanks

[bazmlb]

If it runs ok on LPG then its likely not to be spark plugs, could be an injector sticky or dead, i replaced a dead injector with a 2nd hand one in a Nissan SR20 motor for 400b from the wreckers as an indication of cost if its that.

[hansnl]

It is possible the LPG-running is more efficient as running on petrol.

That said, take care to start and stop the engine on petrol.

I know it starts on petrol and switches to LPG, but try to switch to LPG manually after driving some distance.

And switch to petrol manually when nearing your destination.

This advice comes from a garage specialised in LPG-installation.

Many times customers arrive with petrol problems due to not enough running on that fuel.

The man even thinks this may be due to the ethanolmix.

[VocalNeal]

Some LPG systems, like those in taxis, are open loop which means they get no feedback from the O2 sensor. If the car is running too rich or too lean the O2 sensor sends a signal to the ECU to either increase or decrease the amount of benzine. The ECU can't do this as the benzene is switched off so on some cars the "engine" light comes on to indicate an emission control problem.

If your car runs 98.8% of the time on LPG and you have an open loop system (not injector based) your benzine engine management system gave up the fight a while ago and has defaulted to rich. If worried try using benzine a bit more for a long journey, if not particularly bothered ignore it and continue to use LPG.

You could try a bottle of fuel system cleaner and run a whole tank of benzine through the system?

One of my vehicles has the same start on benzine system. I run the engine at idle until it warms up ( start engine first load up stuff second), not long in this country then drive away and it instantly turns to LPG within less than 10m

Edited April 17, 2014 by VocalNeal

[sunny747]

my car is over 10 years old but well maintained . so not sure if it is open loop system . i assume it's a injector based.

so like one poster suggested, i should just clean or change the injector ? is it going to help? surely i never changed or cleans injector ever.

it doesn't sound too expensive.

thanks all of you who dropped by. really helps.

[sunny747]

okai naive question if anybody knows...fuel injector , how do you say it in Thai ?

[wprime]

Do you get a lot of smoke coming out of your exhaust when you put the foot down on petrol? What colour is it?

[WarpSpeed]

System needs proper tune up timing and all to more accommodate gasoline and alcohol mixtures it sounds like you're describing pinging or detonation which is a fuel problem more than anything and you should deliberately run it on gasoline multiple times daily depending on drive time and distance I just posted this recently on another thread here so the explanation for doing that is written there.

[jay1980]

if it runs good on LPG but not on petrol, try cleaning or changing the fuel filter

cheers

[WarpSpeed]

It is possible the LPG-running is more efficient as running on petrol.

That said, take care to start and stop the engine on petrol.

I know it starts on petrol and switches to LPG, but try to switch to LPG manually after driving some distance.

And switch to petrol manually when nearing your destination.

This advice comes from a garage specialised in LPG-installation.

Many times customers arrive with petrol problems due to not enough running on that fuel.

The man even thinks this may be due to the ethanolmix.

Actually that advice comes from me here after several posts going back years.. But you mean manually switch to petrol not LPG presumably..

[VocalNeal]

Automatic LPG systems start on petrol because the liquid LPG passes through a water heated vapourizer to convert it to a gas. In frigid climates the engine has to warm up so that the heat from the radiator can be used to turn liquid LPG into a gas.

The boiling point of LPG is very close to 0 deg C so in Thailand there is no real need to start the vehicle on petrol/benzene, the vapourizer is well above zero and there is enough latent heat in the cooling system to do the job even with the engine stopped.

So why do Thai systems do this? Simple. All of the LPG systems are imported. The countries that use the most LPG in cars are countries like Poland, so the systems are designed to work everywhere even at temperatures below zero.

In Thailand if one has an open loop inexpensive manual system it can be left on LPG and the car can be started and driven with no problem. One should also note that an auto LPG system does not switch back to petrol when you are nearing your destination. Neither do they have a lag system like some of the old turbo cars when the engine would continue to run on a timer when the engine was switched off, to allow the turbo to cool down. If running on petrol at the end of a journey was important then they would have such a system.

Not forgetting of course that there needs to be some benzine in the fuel tank of an EFI car to cool the fuel pump which runs even in LPG mode.

Edited April 21, 2014 by VocalNeal

[chuenyongman]

We purchased a new Mitsubishi Lancer 1.8 Liter . We had L.P.G. installed. Only done 28000 kilometers and on third set of sparks plugs already. Anyone know why?

[VocalNeal]

LPG runs hotter than gasoline/petrol so you need different plugs. Also for LPG the ignition system has to generate higher voltage to "jump" the spark plug gap. This can be mitigated by setting the gap 0.1mm less than your manual says. See link below.

I researched this awhile ago for my Suzuki trucks but gave up on locating the correct LPG plugs easily.

There are special plugs for LPG but here they are about B600 each. Solution use one grade harder than std and reduce the plug gap. The problem them becomes finding odd ball plugs, so use normal ones with the gap less and change them every time you change the oil. Normal spark plugs are about B600 a set. Labour is inexpensive here.

So with LPG you need to run one heat range "colder" and set the gap 0.1mm less.

It is easy for NGK the higher the number the harder or colder the plug. So if the stock plug is say a BKR6E then for LPG use a BKR7E. The problem being is that unless the BKR7 is a common plug used in other vehicles it will not be super easy to track down. Which is why it is easier to continue with a 6 and change more often.

Have a 165,000 on one of our LPG trucks and have the plugs changed at oil change. Yes one can use "special" LPG plugs but the cost works out to be the same.

In the OP's case (Mitsubishi Lancer 1.8) the stock plug for his car is Denso K16PR-U11 which is a NGK BKR5E rating plug. So it is easy as the Suzuki Carry uses a BKR6ES which is equivalent to Denso K20PR-U11 (and yes I know the NGK doesn't have a V groove)[/size]

So the OP can use plugs from the Suzuki set the gap down from 1.1mm to 1.0mm and change then at every oil change.

So luckily for your Mitsubishi use commonly available NGK BKR6ES or Denso K20PR-U11 which is the stock plug for Suzuki Carry 1.6. and set the gap less by 0.1mm. and change at each 10,000km oil change.

This is the pragmatic solution.

If you can easily find them and if you wish you may use Iridium plugs BKR6EIX-11 but only because they have a smaller center electrode and will be easier on the ignition system. You don't have to set them 0.1 mm less.

Edited July 6, 2014 by VocalNeal

[MadMac]

Agree with VocalNeal here, most of the LPG systems are open loop. The gas is sucked in the engine right behind the airfilter and bypasses the injection. Petrol is switched of completely. If you never run on petrol, your injection may be blocked, old fuel, dirt, water, god knows.

[WarpSpeed]

If running on petrol at the end of a journey was important then they would have such a system.

Not forgetting of course that there needs to be some benzine in the fuel tank of an EFI car to cool the fuel pump which runs even in LPG mode.

Neal this is not the case, It's quite presumptuous, these are cheaper systems priced for the market and a feature like this would be quite costly to install and program with it's own ECU's and such, not to mention the tech training and understanding to install and properly apply such equipment which fall short in Thailand on a mass scale. That doesn't mean it isn't necessary nor good practice..

Edited July 8, 2014 by WarpSpeed

[VocalNeal]

If running on petrol at the end of a journey was important then they would have such a system.

Not forgetting of course that there needs to be some benzine in the fuel tank of an EFI car to cool the fuel pump which runs even in LPG mode.

Neal this is not the case, It's quite presumptuous, these are cheaper systems priced for the market and a feature like this would be quite costly to install and program with it's own ECU's and such, not to mention the tech training and understanding to install and properly apply such equipment which fall short in Thailand on a mass scale. That doesn't mean it isn't necessary nor good practice..

Even with all the hitech stuff it would be impossible for the system to know when one was approaching the end of the journey. My original statement was an attempt at humour based on this. Someone gave me instructions to their house once which were turn right after the last speed bump! But back on subject all systems have an off switch if one really believes that this practice is necessary.

Not all the systems here are cheap ones, some cost $1000 plus and more. Not worth buying of course unless one does enormous mileage but...

[WarpSpeed]

OK I understand, I know the destination option would obviously never be possible but I was more referring to the lack of need to cool the system manually before destination was achieved.. I read it as you saying that wasn't a necessary step in operating one and really it isn't if one does not wish to get the best possible effect of an LPG system with the least possible vehicle wear. BTW I know that some systems are expensive I.E. multiport, but the primary basic systems aren't quite so. Still I always bought cars with them already installed and got my money out if it immediately that way.

Edited July 8, 2014 by WarpSpeed

[VocalNeal]

OK I understand, I know the destination option would obviously never be possible but I was more referring to the lack of need to cool the system manually before destination was achieved.. I read it as you saying that wasn't a necessary step in operating one and really it isn't if one does not wish to get the best possible effect of an LPG system with the least possible vehicle wear. BTW I know that some systems are expensive I.E. multiport, but the primary basic systems aren't quite so. Still I always bought cars with them already installed and got my money out if it immediately that way.

I've got two "identical' vehicles one with a basic taxi system and one with a multipoint injection system (because I forgot to tell them!) I can't really say there is any appreciable difference in the driving just the operation.

The injection one always starts on petrol and switches to LPG as one drives away assuming the engine temperature is sufficient so I always start the engine and then load the truck. Also it beeps and switches back to petrol sometimes if the tank is low and i make some sudden moves. like passing from a low speed..

The basic system starts on LPG and dies when the LPG runs out. Then it has to be switched back to petrol manually.