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[Craig_R]

Hiya chaps need some help with some info on my LPG system, more so from people who have DIY installed them as its a set up thing.

ill try and keep this short so bear with me please.

Right My lpg system Which is a MIXER SYSTEM has been alittle iffy of late so by prue chance a hand held system appered on ebay for my LPG system(its not the kind you can plug in to a laptop) it needs this hand held system to Diagnostic and test it.

So i plugged it into the LPG ECU and it worked thankgod but i dont understand much of it to be honest but i do some.

The first thing that was wrong in the settings on the LPG ECU was the O2 sensor was set as a Zirconia sensor which gives a 0-1V signal, and the hand held system reported it was running Lean. But as I have only just changed my O2 sensor I know the 2 litres run on a Titania sensor operates between 0-5V, so i changed it over on the LPG ECU, it reported after acouple of tweeks it was running rich, then lean then back to rich and so on, which i think is correct for it to do so, as the ECU on the car does tthis runs it lean and then rich over and over.

Am i right in thinking that if the LPG system thought it was a 1V lambda and was reporting it as lean all the time it would pump more gas into the engine to try and make it richer, IE why my MPG has been aliitle on the poor side.

I know that aleast by checking the 2.5 runs a Zirconia sensor which gives a 0-1V and only has 3 cables from it.

Does anyone who installed there own system have any note or manuals that came with their system i can have a copy of to throw some light on the different readings i am getting from the hand held Diagnostic and testing device.

One thing i did change was the middle solenoid  the one with the filter in it knacked up and would not open all the time so the valve was removed so it is always open but there are two others one on tank and one on the Vap/reducer.

Any Help Would be Great

Craig

[Kevin Wood]

I should say I know very little about LPG systems, however, the Lambda sensor behaviour sounds right. The sensors fitted to most cars don't give feedback of an accurate mixture but they have a "knee" in their output voltage at stoichiometric (chemically correct) mixture. This means that the correct behaviour of the ECU in closed-loop running is to lean off the fuel mixture until the lambda sensor starts showing a lean mixture, then richen it slightly until it shows rich. This way the mixture alternates slightly around the chemically correct mixture that's important for the catalytic converter.

So, it sounds like your Lamda sensor was set to the wrong type.

You are correct that it would have been running rich previously. Most systems have a range of adjustment they will allow (you may even be able to configure this) so it would have ramped up to the richest mixture it could and then sat there. This would have resulted in poorer fuel consumption.

Is it running better now you have made this change?

Kevin

[Martin_1962]

Sorry no experience of closed loop but Kevins advice seems sound, mine BTW uses the car ECU to control timings

[Craig_R]

Thanks Kevin What you said makes alot of sense

But as it was set in the LPG system as a 1V O2 lambda sensor not a 5V as the lambda is in my car
it would of been taking the readings from 0V-1V (0volts being lean and 1Volt being Rich) would it of gotten to 1V and started to lean off the mixture, would this of not made the system run lean ?
Or Am i getting this backwards its Confusing me this lol

my read outs 5v rich 0.3v lean thats what it flicked back and forth from when set to the 5volt lambda in the LPG ECU.

i have not taken her out for a spin yet as i need to look into TPS (throttle position sensor settings) the voltage and the degrees its at, as i am trying to fully understand this :-? :-? :-?

Oh i found some info here about lambda sensors

http://www.picotech.com/auto/lambda_sensor.html

[Craig_R]

I think I have figured out why my LPG system is not working tiptop.


I have remembered that when i got my head gasget replaced the mechanic did say he unplugged the ECU to put it in a safe place so it was unplugged for acouple of days and i think the LPG ECU has reset its self to default as its been not clicking to gas when the throttle is beeped upto 2000 revs and acouple of other things.


By the hand held tester it says the water temp is set to 15 degs for it to click over alittle low i thought.


I might need to calibrate the LPG ECU shame i dont know where to start, but i guess ill just try some settings out it can be worse than it is now set to default

If anyone knows of water temps and throttle positions please by all means type way

Craig

[Craig_R]

Guess No one can help me with this issue  

Well with some trial and error changing some values on the LPG ECU i have stop the LPG system just clicking in at and time, only clicks over now when the throttle is Bipped and the revs go over 2000.
also the Gas System seems to be running at the right leaness and richness at idle, ill find out more when i take it for a run to see if its ok when driving.

I also changed the Throttle position Setting To P+ instead of P- when at idle it was showing 79degrees and the degs dropped when the throttle was opened, Now with it set to P+ it is at 1 or 2 degrees at idle and gos upwards I think this is right  :-/ :-/ :-/

I hope i get all the settings right  :-/

ill post all the setting the hand held device shows from the ECU and the abreviations of some of the setting to see if anyone can shed some light on what they might stand for.

Ill be an LPG installer at the end of all this  

[Kevin Wood]

A print out of everything you can tweak would be useful.

Maybe we can make some sense of it and give you some guidance.

My main worry would be the fuelling at maximum load (full throttle). If this is too lean it will burn a lot hotter than normal and could melt a piston or burn out a valve. At least this is true of petrol tuning! You won't do harm running around under light throttle whatever's happening but steer clear of full throttle until you know the mixture's OK, which may well mean taking it to an LPG specialist. I'm not sure how they set them up when fitting.

I set up my car using a wideband lambda sensor which is able to read fuel mixture over the whole operating range of the engine. With a narrow band sensor it'll need to be much richer than the sensor's normal switching point so it'll be reading rich all the time. Then again, I'm talking about petrol again..

Kevin

[Taxi_Driver]

I think I have figured out why my LPG system is not working tiptop.


I have remembered that when i got my head gasget replaced the mechanic did say he unplugged the ECU to put it in a safe place so it was unplugged for acouple of days and i think the LPG ECU has reset its self to default as its been not clicking to gas when the throttle is beeped upto 2000 revs and acouple of other things.


By the hand held tester it says the water temp is set to 15 degs for it to click over alittle low i thought.


I might need to calibrate the LPG ECU shame i dont know where to start, but i guess ill just try some settings out it can be worse than it is now set to default

If anyone knows of water temps and throttle positions please by all means type way

Craig

On my 2.2.....its set to swap to lpg when the water temp is 40C or higher and when the revs are falling from 1800rpm (hence why you need to blip the throttle) Also set to switch 30secs after starting if the water temp is already 40C or higher.

Altho I reckon you could try reducing timing and water temp slightly.

HTH

[Taxi_Driver]

I'm not sure how they set them up when fitting.

Exhaust fumes analyser   or at least the place i go to....does it that way.....probe up the exhaust and look at the readings over the rev range.
I think the lpg pressure is regulated by an adjustment on the evapourator....i dont think the lpg ecu plays any part in the gas pressure....so it shouldnt have changed.

[Martin_1962]

I dropped my temperature down to mid 20s and just be carefull for first mile or so (saves 20 - 30 seconds of petrol). I also switcjed mine to change over when over 1800 so it will change when driving along, the dropping method is for manuals

[Craig_R]

Thanks Kevin TD and Martin.

Ill keep an eye on it today when i test drive her kevin i am going to have the hand held Diagnostic system plugged in to keep an eye on the richness to see if it levels out.

TD 40 Degress ill see about making it 30 degs and see what its like. Oh and the switching time ill have a look at that also thanks mate did not know about the switching time if its already up to temp.

Martin Thanksmate ill have a look to make sure i set it to switch over when revs are falling from 1800rpm as mine is a manual

Its starting to make some sence now thanks everyone, ill post up some photo of the testing kit with all the different screens it shows and what you can change