So my old shitbox drives on both LPG (autogas) and regular petrol

So my old shitbox drives on both LPG (autogas) and regular petrol.
Now, when I drive on LPG, for obvious reasons, I always seem to have lower RPM (around 500, sometimes gets as low as 200-300) while idiling than I'm driving on petrol. Sometimes the RPM just keeps declining until the engine stalls completely, after which I have a pretty hard time getting it up and running again. Today it happened at a traffic light, I had to push my car to the nearby parking spot and switch it over to petrol to get it to work again.
I could just slightly open the manual choke and leave it like that to reach 900-1000 RPM as I normally would have when idiling on petrol, but that feels like I'm ignoring the problem.
Is it normal for LPG to have a lower RPM when idiling, due to differences in combution or something? Is it harmful to permanently leave the choke more open to get a higher RPM? I'm a total noob when it comes to this and my Veeky Forumscd kicked in really hard today when I barely could get it to start again.

>tl;dr lower RPM (sometimes causing engine to stall) on LPG than on petrol, is it normal?

LPG has less combustible energy than gas, so your answer is yes...

I feel like a retard now, but thanks

What car is it?
What type of LPG do you have?
What type of fuel delivery system does the car have for petrol?

my Volvo is LPG, it's normal.

VAZ-2106
Not sure, what kinds are there?
Fuel injection

Does the LPG attach to the intake from the vaporizer or are there injectors?

My car idles perfectly fine on LPG, I don't think what you're experiencing is normal

I honestly wouldn't know, but since the petrol is injected the LPG might be as well.

Well, electrical choke that is calibrated properly? Mine is manual.

The problem you are experiencing is more prominent in non-injection LPGs, because of the way the fuel is delivered. You could try to fine tune it through the vaporizer. There is a valve that changes the pressure under which the gas passes through it. If you find the model of the vaporizer, you can find how to change said pressure to not experience this problem.
If it is injector type LPG system, there should be an ECU somewhere which you can find software for and you can buy cable off of ebay for like $15 or some shit that you could plug to a computer and run calibration once again or map it yourself.

I doubt it has ECU. As you might know all VAZ engines have minimal reliance on electrical components. That being said, would you know where to find the vaporizer? I can deliver some pics if needed.

Would it harm to leave the choke open to reach 900-1000 RPM though? That would obviously be the easy way out.

Just make a nicely lit picture of the engine bay, we can work from there.
I doubt it would harm anything more than stalling.

I will post first thing tomorrow since it's 2AM here now. Thanks though!

Bumping for OP.

Thanks lad.

Here it is.

This shit should be the vaporizer, can you make a picture of it?

Here ya go

Do you see where the Idle sticker is pointing at?
Turn that shit with a screwdriver.

I just wanna ask some questions:
Does it happen always, or only when the engine is cold/hot?
Does the car drive fine otherwise?

Sounds like you have a lean mixture at idle, but better to check simple things first...

Is it that easy? I read online a bit about tuning the LPG vaporizer on cars and they always mention multiple bolts that have to be screwed and adjusted.

I'm not sure, it's weird. It mostly seems to happen when the engine is hot and has been running for a while already. The idle RPM gets lower and starts decreasing slowely. For example, when I left home yesterday on a cold engine it was idiling around normal RPM if I remember correctly. When I arrived at my destionation (10~ km away) I waited a while in the parking lot to see how the RPM is behaving. It was decreasing before my eyes.
The car drives perfectly otherwise.

You can always try. And if that doesn't work, just read up on this model of vaporizers.

>lada
>LPG
>true gopnik

The less you spend on gas, the more you can spend on an excessively expensive stereo system in your Lada [le black man pointing at forehead meme]

Can I just leave the engine running while I do it?

Indeed, the landwirtschaftliche Produktionsgemeinschaft was a east german thing, and east germans were not gopniks.

It revs too low at idle.
my car that is factory LPG no petrol idles at around 1000rpm for a 4l i6

How else would you understand if you are doing anything?

Again, could just be that your electrical choke is adjusted properly.

Umm, I'm no expert, but check the coolant level (the vaporiser needs coolant heat to work correctly) and that the engine gets up to operating temperature.

If that's right, look up how to adjust idle speed and mixture for that model.