Not switching from Petrol to LPG- Landi Renzo system

[BorderCollie]

I have a "W" Reg'd Citroen 1800cc Xantia, which I bought 3 years ago with a Landi Renzo lpg conversion that was installed by a previous owner in 2005, about 3 years previous to my purchasing the car.
Last November, I had to take the car to a great lpg mechanic in Glasgow (Thanks Dougie, highly recommended!!) and he cleaned the system and replaced the faulty vapouriser, as after automatically switching from petrol to lpg, the engine died and stopped.
It has since worked fine up to last week.
Lately, on switching on the ignition, I have been getting a 'red light' for 3-4 seconds on the lpg switch unit, then it returns to the normal flashing green/orange lights, as it waits to switch from the petrol to lpg running. It then automatically switched from petrol to gas as normal, after about 2 minutes of the engine running(which has always been the norm for my car)
However, since 3 days ago, on ignition switch-on, I get the normal green/orange flashing lights on the switch display, but both stay flashing, and despite driving for the next 20 minutes, or for several miles, it won't switch from Petrol to lpg.
Saying this, I thought this fault had rectified itself earlier today, as after 15 miles of continous driving, it suddenly automatically switched from Petrol to lpg, and then ran perfectly well running on the lpg, all the way back home.
However, after turning the engine off, and trying to start the car up again after an hour, despite driving 15 miles into town, it wouldn't switch from petrol to lpg once more.
My suspicion is either faulty solenoid or temperature sensor, or does anyone else have any suggestions?
Thanks,
Davie (Border Collie)

[Gilbertd]

My suspicion is either faulty solenoid or temperature sensor, or does anyone else have any suggestions?

More likely the latter. If it was a faulty solenoid it would switch as normal and promptly die from a lack of gas. As it isn't even attempting to switch then it doesn't think the parameters for running on gas are correct. That would be it thinks it's too cold (temperature sensor) or it thinks it has no gas (pressure sensor).

[BorderCollie]

Many Thanks @Gilbertd- I do suspect the Temperature Sensor, but would this fault include the red light showing for 3-4 seconds occasionaly at ignition switch-on?
Are the Sensors expensive and time consuming to replace?
boder collie

[Gilbertd]

Don't know the Landi system very well but the temperature sensor is normally fitted onto the vapouriser. They cost roughly 15-20 quid and just have 2 wires on them. The fact that yours has worked occasionally suggests it may have come adrift from the vaporiser and is not detecting the temperature or simply has an iffy electrical connection.

[bxman]

Is it a LCS/2 system ?
( I have the same car although P reg.)
If so I run mine without the temp sensor connected, without any problems and it has saved a lot of of Petrol since I did so 18 months ago.
I have some documentation somewhere I could try and find if it would help.
let us know.
you could have a later system

[bxman]

That will save me the trouble of looking for it.
He will have to send me a PM.
If he, the OP, would like me to bother.
cheers one and all

[BorderCollie]

Thanks for your replies-
I believe I have the earlier system, as 'Dougie', the lpg mechanic up in Glasgow, tried the LCS/2 Management programme on his laptop, plugged into the ECU, and it wouldn't recognise the system.-
During the last 3 days, when it has been really frosty (up to -6 Degrees), on ignition switch-on, the red light on the Petrol/lpg switch shows, but if I then start the car up whilst the red light still shows, strangely it switches onto gas after a couple of seconds, then runs on it until the ignition is switched off again.
It seems as soon as the engine heats up, on restarting the ignition, the lpg refuses to switch on.
Temperature sensor??
Thanks again.

[bxman]

Find the Landi Renzo control unit it will point you to the type that you have.
It is rather important to know what you working with in the first place.

[BorderCollie]

Checked this morning-
Label on the Control Unit says:
LANDI RENZO SL96
PROGRAMME SL96-3
EMULATORE LR25
LAMDA CONTROL SYSTEM 2-VO5/2

Thanks again!

[bxman]

It is a LCS/2 you will have an SE 81 SIC vap

try this link

http://catalogo.landirenzo.com:88/scrip ... 2038dd2ac3

http://www.landi.it/

is the main link you will need to select the English option.

As I said it should run with the temp sensor disconnected.
I suspect you have a iffy electrical connection some where along the line.
I will try and find some data on the lights and post back if I have success.

Now that we know what we have with luck someone else may be able to help.

It's the software I have found on the computer .
the documentation is some where else.

[BorderCollie]

Thanks for the info- it's still occasionaly switching on the lpg immediately on ignition start-up, but not when the engine has heated up. It runs fine using Petrol only.
I'll try to locate the temperature sensor tomorrow, and disconnect it to see if that would work.
Problem is, the vapouriser is situated right under the large air filter, in an awkward place (would it be anywhere else!)
The fault definitely seems to be temperature related. Just keeping my fingers crossed it's not the Control Unit!
Regards,

[bxman]

Now found some details re switch lights
bottom left
solid green = running on gas
rapid flash = stand-by for change over to LPG
slow flash = malfunction during LPG operation

top left (red) = LPG fuel level on reserve

top row green(s) denotes degree of LPG level in nominal fourths

bottom right orange= petrol operation.

If you need any other information give us a shout.

The controller is pretty robust .

The problem, I think, is configuring the serial port.

I have not yet succeeded despite 2 or 3 extended attempts.


I have a disc with software and I thought there was documentation on there but I cannot see it. only a PDF there covers a Lovato lambda control system which could well be the same .
probably both (aeb) { now owned by LR }
lets hope there is someone about that can put me right on this speculation
If it would help, I could attach the PDF to an e-mail if you would like.

[Gilbertd]

AEB, Lovato and Landi are all totally separate companies, although the Landi Omegas ECU does look remarkably similar to an AEB one and the Landi switch appears the same as the AEB 119B switch.

[BorderCollie]

I tried checking if the temperature sensor was connected to the Vapouriser, but apart from the gas pipe, the only other connection is the pipe connecting the Vapouriser to the water pump- this pipe has what looks like a solenoid attached to the midway it, with a 4 wire connector. I can't actually find the temperature sensor anywhere, to disconnect it!!
As for the switch unit on the dashboard- Top Row has solid 3 green led lights (I know the lpg tank has at least 30 liters of lpg still left in it)
Bottom Left led , after ignition turn-on, has rapidly flashing green led, indicating it's standing by for change-over from Petrol to lpg.
Bottom Right led, also after ignition turn-on, has the normal solid orange led indicating it's currently running using Petrol as the fuel.
Still got the same problem- the car will only switch from running on Petrol, to running on lpg gas, whenever it feels like it- today it switched itself from Petrol to lpg, almost immediately after starting the car up, long before the engine water temperature had heated up- after driving 5 miles into town, and the water temperature gauge reading the usual 80 degrees, and then switching off the engine for only 10 minutes- on restarting the car up, it refused to switch from Petrol running to lpg, for the full 5 miles return home journey.
By the way, when it does switch to run on lpg, from the Petrol, the car runs perfectly fine- no misfiring, cutting out, or switching itself automatically back from lpg to Petrol-
Driving me barmy!!
Any ideas, please??

[Gilbertd]

I tried checking if the temperature sensor was connected to the Vapouriser, but apart from the gas pipe, the only other connection is the pipe connecting the Vapouriser to the water pump- this pipe has what looks like a solenoid attached to the midway it, with a 4 wire connector. I can't actually find the temperature sensor anywhere, to disconnect it!!

There will be two water pipes, a flow and a return. I suspect if there is no temperature sensor on the vapouriser, then the thing in the hose is the sensor. You wouldn't have a solenoid in the coolant hoses.

[BorderCollie]

The image below shows what I think is the temperature sensor- as I posted earlier, it looks like a solenoid but is actually half-way in the rubber pipe, betwen the Vapouriser and the water pump.
I don't understand Italian, but the lable says (in tiny letters)-
ATTUATORE
TIPO FLLIDO
TEMP LAVORO
PRESS MAX LAV 12v
It has actually 4 coloured wires connected to it- tried starting the car with the connector unplugged, but although the green flashing led indicated it was 'ready to switch to lpg', it wouldn't.
I'm wondering? If it looks like a solenoid, could it actually be a joint solenoid and water temperature sensor, that only opens the pipe from the water pump to the Vapouriser, when the sensor has detected that the temperature has reached a certain level? If the solenoid has failed, and has shut off the water supply, would the temperature sensor then not actuate, and thus stop the lpg from switching on from the Petrol?
Advice invited, thanks...

Taken from above-pipe from water pump to Vapouriser showing 'Solenoid'?

Solenoid 01.jpg (87.06 KiB) Viewed 5328 times

[rossko]

That's a standard stepper motor actuator. I have never ever seen one in a water pipe. As its been there for years it has probably now seized in an open or shut position.

You'd normally find them in the gas pipe between reducer and mixer, but your system may have something similar mounted directly on the reducer? I think we have a problem here from "installed by a previous owner" (i.e. major cockup)

[BorderCollie]

Gulp!!
All I know was that it was installed 'profesionally' in 2005/06, by a Company 30 miles away located in Carlisle-"Autogas Carlisle" but they're no longer at their address.
So.... wonder where the actual temperature sensor is, as I've searched everywhere.

[rossko]

Perhaps it doesn't have a temperature sensor, a great many single point (mixer) systems don't.
If that is the case, it's lacking RPM signal. Might be a wonky connection or a wounded ECU (rpm input has a hard life if it is picking up from ignition coil, as is common)

Only guessing from very limited info, but I would suspect your system has been running open-loop all this time - which isn't the end of the world. And the stepper in the water supply is completely unwanted.

Here'sa pic of usual stepper usage
http://www.lpgexpert.ro/Kia/KIA-Clarus- ... ductor.htm

[Gilbertd]

Are you SURE that is in a water hose and not the gas feed pipe? A single point system should change over almost immediately and not need to wait for anything to get up to temperature.