LPG Conversion

[Brianmoooore]

What size is the venturi in the mixer? (If it exists).
To tune your system - Open up the valve in the hose completely, close the 8mm screw on the reducer, and with the engine at running temp, adjust the 10mm screw for a good idle.
Hold the engine at about 2500 RPM and close the valve in the hose untill the engine starts to slow. Open it up again about 1 1/2 turns.
Go back to idle and adjust the 10mm screw again, then adjust the valve in the hose at 2500RPM again. Keep doing this untill they don't affect each other any more.
This should all be done with a gas analyzer, of course, but the above will be close.
I would still recomend investing Ԛ£100 or so on a Leonardo closed loop set up though. Much easier to set up and keep right, and you can see what's happening on a laptop. Easy to do on the M50, as you've already got a proper TPS and a lambda sensor.

[philglasgow]

That's less than 10 MPG!. Should be more like 22, so somethings wromg.
Your system is so basic, that assuming the engine itself is in OK condition it can only be down to tuning.
I wouldn't go for a variable mixer, because a backfire would close it up and blow your inlet manifold to pieces. I've no experience of them but some people recomend them, and others say they have no benefits at all. An ordinary venturi mixer should do fine. There is one inside that pipe isn't there?

Yes Brian I had the plastic pipe off and there is a mixer inside I also cleaned the mixer with carb cleaner .
If the maf was disconected ( which it has been as I had a backfire and suspected it damaged) the car will go into limp home mode, but if connected , although not being used would this help, Im reading conflicting info and am becoming slightly confused .

At this rate i would be cheaper and a lot quicker on petrol.

[philglasgow]

What size is the venturi in the mixer? (If it exists).
To tune your system - Open up the valve in the hose completely, close the 8mm screw on the reducer, and with the engine at running temp, adjust the 10mm screw for a good idle.
Hold the engine at about 2500 RPM and close the valve in the hose untill the engine starts to slow. Open it up again about 1 1/2 turns.
Go back to idle and adjust the 10mm screw again, then adjust the valve in the hose at 2500RPM again. Keep doing this untill they don't affect each other any more.
This should all be done with a gas analyzer, of course, but the above will be close.
I would still recomend investing Ԛ£100 or so on a Leonardo closed loop set up though. Much easier to set up and keep right, and you can see what's happening on a laptop. Easy to do on the M50, as you've already got a proper TPS and a lambda sensor.

Brian

The car idles beautifully on gas( better than it does on petrol) and the engine although high on miles is in good condition

Can you elaborate a bit more on the Leonardo closed loop set up .
How much is involved in this and were would i purchase it from .
I like the 520i its comfy , nice to drive etc so would like to get it sorted if possible .

Is the laptop s/ware and leads easy to come by and are they expensive?

What is a TPS also

Sorry for so many questions Brian

[Brianmoooore]

The AEB Leonardo consists of a small ECU , a petrol/gas changeover switch combined with a LED fuel gauge, an electric valve similar in construction to an idle control valve, which replaces the screw valve in the gas vapour line and a wiring loom.
The loom connects to permanent live, ignition live, ignition pulses, gas fuel level sender, lambda sensor, TPS (throttle position sensor) and has a couiple of wires for disconnecting the petrol injectors.
The interface lead for the laptop is easy enough to make up, or can be bought, and copies of the software can be obtained easily as well.
Try Tinleytech or Gaskitsdirect for the hardware.

[philglasgow]

Hi Brian

The car is going into my local installer on saturday to see whats wrong.
Im looking for clarification if possible please that the air flow meter and lamda( if possibly faulty) would have no influence whatsover on the lpg running of the car as the single point is not clever enough .

My installer has offered me a new sequential system fitted for Ԛ£800.00 if i keep my old tank and pipes is this good ?


also do you have the full email addy or phone number for gaskits direct

Thanks



Phil

[Brianmoooore]

Got the name wrong for a start. It's www.lpgkitsdirect.co.uk
Ԛ£800 for an injection kit fitted, set up and certified is about the going rate in this country i would say.
The lambda sensor and air meter missing would not make any difference on a M20 engine, except for possibly a slight change of timing, but the M50 ECU would certainly miss these sensors, and light the engine fault light. If it doesn't, I would expect that the bulb has been removed.
I don't really know enough about the M50 ECU set up to know whether or not it has a limp home mode, and what difference if any this has on the ignition side of things. If it does anything, it would probably retard the ignition considerably. Anything it does to the fueling side is unimportant, as you don't use this when on gas.

[philglasgow]

Thanks for the reply Brian

I know that the maf /lamda not working would effect the car performance on petrol , but as i only use petrol to start the car im not concerned.

As long as it has no adverse effect on gas running ( especially mpg) i dont mind.

Im considering fitting a new lamda though , but at over 80 quid from euro im condsidering fitting 1 of the universal type they sell at around 30 quid, have you or anyone reading had any dealings with these products?


Phil

[Brianmoooore]

I've been using a universal lambda sensor from Eurocarparts (or possibly GSF) for four years and it's still working fine.
In fact, because I thought it might be faulty, ( see recent "missfire" thread), I swapped it with one from a M54. Apart from the leads and plug, they looked like the same part.
You need to find out if your M50 retards the ignition when the ECU's unhappy.
Does the dash engine fault light illuminate?

[philglasgow]

I have never seen the fault light come on as of yet , If I am going to get 1 the universal will be ok i just need to specify the number of wires .

Thanks


Phil

[Brianmoooore]

Pull the connector of the valve for the carbon cannister in the petrol vent line. This turns on my fault light (on the M50 engined touring) after a couple of minutes driving.
If yours doesn't come on, then check the bulb is good/fitted.

[philglasgow]

update


The plot thickens , I filled tank again this morning it only took Ԛ£6.74 worth of gas which works out at 34 mpg ,now im really confused compared with 9 mpg last week, I suppose its possible its not a good filler , but it fills fine then you get the " ergh" sort of noise to indicate its full and i persevere with the trickel fill were the price just slowly goes up in pennies.

I had it back at the installers this morning, who said as the hc were a bit high on petrol also would indicate the engine was needing some work on it , he also said that the lpg mixture was a bit lean and adjusted it up to suit , this however increased my idle speed to around the 1200 rpm mark, he said he didnt want to adjust the idle to suit as this may distrurb the mixture settings again, athough i am tempted to turn the inline volume adjuster to bring them down but as of yet I have resisted this.

I did however re route the k/n to were the original air box used to get its feed from as the viscous fan running may have been causing other problems also.


The equation for mpg is fill it up run it , fill it up again divide the litres taken by 4.546 to get gallons used then divide the miles travelled by gallons , this is correct yes?


Also since being tweeked today I appear to have smoke coming out of the air filter. upon switch off, Is this unburnt gas or something more sisnister. and any ideas as to whatr screw to adjust as i dont want to go back to the installer