LPG Adjustments

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Rubenv340
Posts: 87
Joined: 16 Sep 2012 06:10 pm
Location: Portugal

LPG Adjustments

Post by Rubenv340 » 08 Jan 2013 08:08 pm

Hi there folks,

As i've seen, theres a lot of lpg cars in uk, a lot more than in Portugal, so i'm kinda tired of searching over the internet about tuning the lpg flow.. It looks kinda it's a mistery or something..
I know the best option would be driving the car to a Lpg specialist and make him do an overall maintenance.

The thing is,
I want to learn more and more about Lpg systems... How they work, how they are adjusted, their common problems, etc.
I already kinda know some sort of things, but i want to know more.

The car in question is the Volvo 340 B14-4E. After the reducer, i have a 2 part adjuster before it goes to the mixer.. I've tried already to touch there, and one of them increases / decreases the idle, the other one i can't feel by earing, i suppose it's the amount of lpg that goes in at rpm range.

An old mixer system does have lpg filter? I've only seen them on injection.

Can someone give me some lights and introductions about this?

Cheers.

classicswede
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Re: LPG Adjustments

Post by classicswede » 08 Jan 2013 09:22 pm

Dai

Please email me directly on dai@classicswede.co.uk

http://www.classicswede.com

phone/text 07824887160

Web shop http://www.classicswede.co.uk/

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Rubenv340
Posts: 87
Joined: 16 Sep 2012 06:10 pm
Location: Portugal

Re: LPG Adjustments

Post by Rubenv340 » 09 Jan 2013 09:48 pm

Oh, i see .

Thanks mate, i start to understand how it should work.
I'll post my questions later, w/ photos.

Cheers

classicswede
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Re: LPG Adjustments

Post by classicswede » 09 Jan 2013 10:44 pm

Cool, keep it on this thread and I should be able to help you out.
Dai

Please email me directly on dai@classicswede.co.uk

http://www.classicswede.com

phone/text 07824887160

Web shop http://www.classicswede.co.uk/

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Rubenv340
Posts: 87
Joined: 16 Sep 2012 06:10 pm
Location: Portugal

Re: LPG Adjustments

Post by Rubenv340 » 10 Jan 2013 10:11 pm

My car has been running kinda bad on idle, specially in lpg.
When cold, even with the choke full pushed, i need to keep acelerating sometimes otherwise it stalls.
When at normal temperature, i must have the choke pushed at about 60%, or it will stall too. Even with that, the idle is not stable, sometimes it decreases the rpm irradicaly.
The last few days, when i try to start on lpg, the first try, sometimes it misfires, but second or third try, no problem.

The engine is making a strange noise, like a tac tac tac, cant figure out from where, it's near the carb / bellhousing area, and increases when accelerating.
It also makes a kinda of a Whistling sound.

When running on gasoline, the idle is more stable, i had a last try a couple of hours ago, and it was stable without any choke pushed.
Only takes a little more seconds to start up, but without any problem.
I stopped at the gas station as i went out of lpg, and i was running a few time with gasoline, i did a couple of high revs in neutral and it backfired a 2 or 3 times.

Few facts:

Gaskets (Air filter housing -> carb) and (Carb -> Manifold) and worn out.
Air filter housing placement is bad, it shakes a lot when forcing with my hand for ex., much more than the engine itself, the area where the bolts should be tighten is kinda worn too, one of them can't be tighten anymore.
A high smell of gasoline / lpg in the engine bay.
There is oil around the valve cover (Gasket?)
When shutting down the engine, it shakes a lot too and sometimes it's agressive, lol.

Any advices?
Can it be "ONLY" the gaskets and the air filter housing or anything else? I suspect it cant be only that.

I will try to make a movie or something about the noises.

classicswede
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Re: LPG Adjustments

Post by classicswede » 10 Jan 2013 11:30 pm

Air leaks will cause big problems on LPG. I would also suggest you check the valve clearance (tappets)
Dai

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http://www.classicswede.com

phone/text 07824887160

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gl340
Posts: 25
Joined: 22 Oct 2011 10:24 pm
Location: Serbia

Re: LPG Adjustments

Post by gl340 » 16 Jan 2013 11:01 pm

With worn gaskets engine can not run ok, so you must fix that first before any adjusments made either on gasoline or lpg.

For LPG you need mixer and possiblne air recstriction before air filter to achieve around edit> 3kPa pressure drop for reducer membrane to work correctly and to have LPG responsive from idle to high rpm with same readyness.

On hose valve it is adjusted LPG flow at around 3000 rpm. Then on recuder adjust idle bypass valve by turning usually about 2 1/2 turns.
Then on reducer adjust membrane follow up to vacuum, to obtain good response on foot pedal demand.

Then again adjust idle screw, maybe readjust also minimum at carburetor.
Then again adjust membrane screw which should already have about 3 turns of moving around with good "feel' and now try to find middle of that turns as sweet spot, then very very little turn toward more LPG (turn screw further of sweet spot about 1/4 turn in CCW direction).

If you touch main valve on hose (3000 or so rpm) then you must always go through complete reducer adjustment.

If everything is as should be there will be steady idle, nice response up to around 4500--5000 rpm and then little fall of perfomance above 5000 rpm.

Also, do not forget to open screw at bottom of reducer to clean membrane chamber from tick fluid left after LPG from time to time with engine hot and off.

To be able to adjust LPG engine must before be 100% ok at gasoline especially high voltage electric. Use spark plugs for that engine, depending on year.
Last few years engine needs NGk ZGR5B or similar litlle differnet plug then previous years NGK BPR6ES or similar.
It is easily noticed on prolonged idling and city stop and go driving style.
Hope it helps and always be aware that engine vacuum is determining LPG reducer membrane moving which in turn open more or less valve that allow (inside reducer) FLOW lpg to mixer.

So absolut air tihghtness is essential for proper work of LPG, more then for gasoline.
Last edited by gl340 on 18 Jan 2013 04:36 pm, edited 1 time in total.
1995 945SE AW71L bifuel 205k km
1987 340GL M47 II LPG 208 km
and still rolling

Rubenv340
Posts: 87
Joined: 16 Sep 2012 06:10 pm
Location: Portugal

Re: LPG Adjustments

Post by Rubenv340 » 16 Jan 2013 11:30 pm

Thank you sir, will not forget all the advices.

Any safety advice?
For example, to open the screw at the bottom of the reducer in order to clean, i just need the car to be shut down and cold?

classicswede
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Re: LPG Adjustments

Post by classicswede » 17 Jan 2013 12:38 am

Best with engine hot so that the oil inside is as thin as possible. Correctly mounted reducer should not need this doing.

Engine needs to be off or running on petrol
Dai

Please email me directly on dai@classicswede.co.uk

http://www.classicswede.com

phone/text 07824887160

Web shop http://www.classicswede.co.uk/

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