LPG Gas in a 98 manual VT commodore

[jr689]

Mmm yea I'd be taking it back to the installer as I'm guessing this has only popped up after getting LPG??

Might have something to with the Idle control valve or something along those lines I'm not really sure :/ I'd say it's something mechancical though not tune related as it's doing it on both petrol and LPG and yea my car has the petrol tune and LPG tune (so I've been led to believe) so they work independantly of each other, I guess yours would be the same?

Could also have something to do with the LPG mixer in the intake restricting air flow somewhat... I really have no idea, just throwing idea's out there but yea definitely take it back to him, it's their duty to make it right for you!

 

[DAKSTER]

Not that I am any kind of an expert, but as far as I know tuning dual fuel is a compromise between the needs of the different fuels, hence neither of them are ever truly properly tuned.

To have 'a petrol tune and LPG tune' that are independant of each other, its my assumption that you would need a dual map? If I werent about to switch to gas only, I would definitely be looking at a dual map system I think.

If the car is stalling on both petrol and gas, it sounds like a more general problem than just a tune. Does it idle ok? Is it possible that its something as simple as a displaced vacuum line or something like that?

 

[JoeFish]

Thanks guys,

Oh the idle changes like the weather...sometimes it will idle just below 1,000RPM like normal, other days it will idle on 500RPM and bounce up and down which makes it sound like a purring cat...and also it might even idle around 300 - 400 RPM. It can be really bad when this happens because i might put the clutch in while turning into a shop and it will go right down to 300RPM and i lose power steering and have to rev it a little to get it back (haha). scared me first time it happened.

I am defiantly going to take it back as i have already phone them and told them. It's just very inconvenient and should not happen.

 

[DAKSTER]

Thanks guys,

Oh the idle changes like the weather...sometimes it will idle just below 1,000RPM like normal, other days it will idle on 500RPM and bounce up and down which makes it sound like a purring cat...and also it might even idle around 300 - 400 RPM. It can be really bad when this happens because i might put the clutch in while turning into a shop and it will go right down to 300RPM and i lose power steering and have to rev it a little to get it back (haha). scared me first time it happened.

I am defiantly going to take it back as i have already phone them and told them. It's just very inconvenient and should not happen.

Yep I agree. Decent customer service should include a test drive, the problem should have been rectified before they returned the car to you.

Regarding products you can use on your engine, my gas guy recommends the flash lube system as posted by jr689 above. They even install it and warranty it. I dont use it personally (they didnt offer it when my gas was fitted or I may have bought it), and as far as I know its caused no problems by not using it, but it certainly seems like a reasonable product and worth using.

 

[JoeFish]

Yeah mate i saw that and then when i went into their shop they had it for sale on a stand. Plus they said they'd fit it as well for a total of $110 when i get the 3000km service. I have already done 1000 in just over a week so it won't be far away.

For 100 bucks, it's really worth it especially if it will help keep my valves going etc etc...I'm actually not sure if i really need it lol meh...better to be safe then sorry.

 

[strgas]

have you got any pics of the under bonnet setup and the correct brand name of the system ? would be a big help to see the setup .
dual mapping is rare these days as most EFI vehicles fitted with knock sensor will sense the change in fuel and remap the ecm timing to suit either fuel , older carby cars had alot more tuning issues due the the dizzy curves being totally different from one fuel to the other , LPG can run up to 16 degrees at idle which is not good for petrol but then lpg will run lower advance at higher rpm due to the octane ratings and burn times of the two fuels balancing timing and fuel mixtures is the key when deal with straight gas LPG and petrol engines .

 

[DAKSTER]

So is there a potential power benefit in favour of optimised LPG only vs optimised petrol only on an otherwise identical motor, due to higher octane?

 

[strgas]

if the engine is built for straight gas then yes more power can be made , lpg has a higher octane rating the biggest problem with lpg was the delivery of lpg to the engine , today's systems of injected gas is overcoming that problem , EFI engines have far better air flow thru the manifolds over the older caby manifolds