4.0v8 with lpg wanting to stall

Hi guys i have a lpg conversion on my car (i think the term is multpoint injection system)? but when i start the car it starts on pertol then automatically mixes over to gas.

anyway... after starting the car and just letting it run after about 40 / 45 secs its starts to cough a bit almost to the point of stalling... then starts to pick itself back up again.

also noticed this when starting up and driving off it when it gets to the spluttering stage the car struggles to pull away/accelerate until it picks back up again..

any ideas what i could do to fix it?

the multipoint systems are more complex and use electronics rather than solonoids but is your fault on petrol or gas?
you must make sure that your plugs and leads are in good condition.

i would guess petrol as when you start the car up it will start on petrol then switch over to gas after a few mins. i was thinking about putting that fuel cleaning stuff when i next fill the petrol up to see if that cleans anything. other than plugs what else would i check for ?

yeah the lpg does looks really complex! looking under the bonet i wouldnt like to tinker with it and yeah its got an ecu and all programmed by laptop /software (which i dont have)

run it on gas then run it on petrol, see if the problem is only present on 1 of the fuels that will norrow it down a bit. If its just on petrol then try cleaning the injectors, check the leads/plugs/distributor cap etc (that stopped mine running lumpy on petrol). Not too sure how multipoint works but my singlepoint seems simpler than the petrol setup.

how do i start it up on gas? i have no instruction for the system
it automatically starts on petrol so is there an override to start it on gas?

you should have a manual switch as well , probably with your guage? mine is a sequential system as well and you can switch on a button

grantsmith said:

how do i start it up on gas? i have no instruction for the system
it automatically starts on petrol so is there an override to start it on gas?

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As far as im aware LPG (duel fuel) systems always start up on petrol and then switch over to gas. You can choose to run mine on either at any time even whilst driving just by pressing 2 buttons but it has to always start up on petrol regardless.

on mine (LOVATO singlepoint system) you start it up on petrol, you rev it and when it gets to 2000RPM it will automatically switch over to LPG, the small LOVATO 4 LED "fuel gauge" thingy that has been fitted just above my left knee onto the dash (about the size of a matchbox) will make a small click sound and a little red LED will turn green indicating to me that im now running on LPG, if i would like to switch it back to run on petrol all i have to do is press a small button on the "fuel gauge" thingy, the green LED will start flashing and then i press the other button on it, theres a small click from the box, the revs seem to rise slightly and the green LED turns red indicating to me that im now running on petrol until i press those 2 buttons again.

Start it up and drive it around using LPG and pay attention to how it drives, now SWITCH it over to run on petrol and do exactly the same drive, were the problems only present whilst driving around on petrol/LPG

If you dont know how to switch it from LPG to petrol find out what make your system is and google it for some more infomation.

on a multipoint system it will always start on petrol then turn to gas.you have quite a complex setup and are very limited as to what you can do as everything is done via laptop.you can only check obvious things such as poor connections,plug leads and plugs.one thing you can check is the condition of the dizzy and the wiring that goes to it as the v8 does have problems with the wiring and also the "air gap".the only other thing to get checked is the air flow meter.