Another question about GAS and memcals etc..

[comtim]

I am a newb, excuse the dumb question.

With a car that runs LPG, do performance chips still apply ? Do the computers in LPG cars still map fuel injection and all the other things they control as they would in a petrol only set up ? thanks.

 

[VpV6]

It all depends on the setup.

If you have a gas/petrol setup, while running on PETROL the chip practically behaves like a standard chip for a commodore.

Now when your running a dedicated or gas/petrol setup on GAS the chip will do varied things depended on your gas setup. If you have a single point gas setup on the throttle body, the chip may or may not map out the fuel utilization curves and all of the other stuff a stock one does. (Actually, it probably will map out the above things, but will not alter the mixture to compensate since the setup is very simple). It all depends on the sophistication of the LPG installation.

However if you have a sophisticated multipoint gas setup, the chip will do most things a standard chip will do, map out fuel utilization, knocks, spark timing etc. It will automatically adjust mixture and timing to give optimum performance.

Hope this isnt too confusing!

 

[comtim]

Thanks VPV6.

How can I go about checking what sort of gas system I have? I am pretty clueless on these things. I know the install was done in 92...

 

[VpV6]

Best thing to do is note down the type of converter you have (brand name, model etc.) In case you dont know, the converter is the round shaped device which evaporates the gas. It should have two water lines running to it for heating, a gas input line, and a gas output line.

The gas output line is the big braided hose (about 5/8 size). If you follow that hose you should see where it goes. If it goes into the throttle body, you have a single point gas system.

If it splits off into many gas hoses which go into the intake manifold you have a multipoint gas system. If you think it was installed in 92, you probably have the former system (single point).

As for how advanced the chipping is, it is hard to say. Some commodores have chips which start the engine on petrol then automatically switch to gas, some just start on gas without the initial bit of petrol. If the engine starts initally on petrol, you should hear the fuel pump turn on when the key is switched to ignition without the engine running, regardless if the selector swich is on GAS or PETROL.

If your engine does start with a bit of petrol that is a very good thing. Engines which start directly on gas tend to backfire sometimes and blow the airbox apart! However in terms of performance, they are both equal.

As for how much mapping the chip does when your driving, I have no idea. If you really wanted to know more the best thing to do is to look at the chip itself, find the manufacturer and model then contact them about it.

Good luck with it!

 

[comtim]

Thanks alot :0)

 

[greenfoam]

If your memcal is BBMM, the stock LPG memcal for a VP, then it's something I was trying to figure out last night. I can only find one spark map in there so I'm not sure that it changes anything at all to run on lpg except turn the fuel off, unless there is something in the memcal that adds spark when you switch over but I'm not sure that exsists. I think you could get a fair bit more power on gas if it doesn't do anything to the spark map by increasing the spark but you wouldn't be able to run petrol anymore unless it was BP ultimate or something like that, or ran a dual program memcal and swaped over before you switched back to petrol

 

[comtim]

Interesting..

Well I wont be running on petrol at all really. What Im trying to understand is , when running on LPG, if the standard chip is actually mapping and running anything at all. If it isnt, seems hardly worth looking at chips once I get some mods done...

 

[greenfoam]

Lots of things will be running but the main two things for go fast at wide open throttle are 1st the fuel map and 2nd the spark map, but since LPG burns slower than standard unleaded changing the spark is important, you will go faster on lpg with more advanced spark, I don't know if you would get your lpg to go as quite as hard as 91 octane unleaded just by advancing the spark but you would be closer than you are now : )

 

[woodsy_1]

The starting on fuel is NOT controlled by the memcal this is usually a feature of the gas set up itself (separate controller for gas on v6)You will find on 99% of cars these days are built for petrol and have aftermarket gas systems fitted