lpg poor running

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shealyp38

New Member
Posts
111
Location
birmingham
ive got a dream xxl-n gas system fitted to my 99 4.0 v8 thor and have been having problems with it running on gas when it switches from petrol to gas
on petrol it drives fine and pulls as good as it should,but when on gas its very flat and struggles to pull the car
got home from work today and opened the bonnet and can clearly here the gas injectors clicking away,this noise wasnt there before
is there a way of test the injectors in some sort of way?
 
My Dream xxl injectors click all the time & mine runs perfectly. My LPG Mech tells me it's common on the dream injectors (are yours the blue square block type)?
Could be filters, they can clog up after a while. Otherwise diagnostics is the next step.
 
My mech changed the filters on mine with the LPG service but you can get them on the bay of e. Just get the info from the filters fitted. Pretty cheap. Bad Injectors would normally cause rough running not a general lack of power. Check it on diagnostics first to check the trims etc. If you don't know when the LPG was last serviced it would be worth getting it done anyhoo. Mine needs servicing every 24k before it tells me.
 
Have you tried resetting the trims with your software? I do mine every few months as I tend to get similar symptoms to the ones you are describing.

I bought a cable kit and software that cover most LPG systems that are available in the UK.

My own system is on my 4.6 2000 model, it is a Zavoli type.

The software has an auto calibrate function which asks you to run the engine at a particular RPM and then it calibrates. The car runs beautifully after an auto-calibrate and then after four months or so, needs doing again.
 
If you've got the diagnostics lead, then go ahead and have a look.

Do check the vaporiser pressure - they do tend to drop a little after a few months running.
There will be a screen that lets you see all the pressure and temp parameters on the software somewhere.
See if the LPG fuel pressure is dropping under load ( it shouldn't.)

Also, you should be able to see the exhaust gas sensor feedback, check that you have feedback, and it's not stuck rich or lean. Some LPG kits show a reading of the jet size - based on how much the injectors are open. This can be a useful indication of something blocked.

Yes, you can look at the fuelling, and adjust accordingly.
But I would first look at the ignition - check the plugs - change if neccessary before doing anything else.

I chased around a "poor power on LPG" issue on my old 101. Spent ages playing with the mixers etc,. Trying to get the thing to pull properly on LPG. Changed the leads ( which looked literally like new anyway) and problem was solved by the leads alone...
LPG will find any ignition weakness...

Also, if you've had the conversion for some time - change the filters, and clean the LPG injectors (by disconnecting the injector feed pipe, squirting some carb cleaner, or petrol into this disconnected LPG feed pipe, reconnecting, and running her up on LPG.)

When I do this, I do run the vehicle up to speed, and changeover to LPG at over 50 ish mph, so the engine cannot stall - it will stumble, as it pulls the cleaner fluid through, but this is only temporary.

Yes, LPG injectors can seem noisy - this is normal.
 
speaking through experience and lots of it the dream system is great with good reliability, the injectors on all the lpg systems are prone to failure but clicking is normal.

check pressures .
if there is a misfires at idle using a pliers squeeze the pipe between the injector and manifold with it running on gas this will cut off the flow and that cylinder should change the note on the engine compare all 8 .
check fuel trims using a OBD scanner preferably one with live data . if they are out a long way then run autocalibration , dont forget to save the settings first just in case .

a good rule once you have done an auto calibration is to match the petrol injector times with the running on petrol times ie 2.5 ms on petrol should read 2.5 ms on the petrol injector whilst running on gas . this is done at idle as you cannot do this at any other point .as the loads and throttle settings varies to much .

all the lpg has to do is replicate the petrol in all areas of the fuel map .

if you need one to one advice then mail me and i will pass my number

john
 
had it on my laptop today and i saw around 1.4 bar on the gas pressure
and the map sensor was showing 0.25 bar dooes that sound about right
but i did notice under the diagnosis tab a error code P1005 MAP SENSOR
 
Hi had same problem on my 94 4.6 Hse. Leads change helped a bit then found vacuum pipe soft on right rocker cover and split on left. Almost right now but going to change the coolant temp sensor as still doesn't like starting and idling well when turning over from hot. Best of luck anyway.
 
Last edited:
shealyp38 said:
had it on my laptop today and i saw around 1.4 bar on the gas pressure
and the map sensor was showing 0.25 bar does that sound about right
but i did notice under the diagnosis tab a error code P1005 MAP SENSOR
Click to expand...

did you clear the map sensor error ?
if you did did it return ?
if it did return the map sensor is dead.

the pressure and the map should change slightly when reving , they should not be static
 
checked it again and the map sensor error didnt return
ive had my lynx hooked upto it again and im still showing faults with the o2 sensors
1 fault is saying heater malfunction and the other is o2 signal missing
both faults are on both banks aswell
but im getting a voltage reading from the sensors which i thought if the signal was missing there wouldnt be a voltage reading
where can i get 2 decent brand o2 sensors from
 
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