p38 Back fire

hi

my p38 4.6 has just started to back fire now and again but not all the time ( My god its load )
this only seems to happen when i run it on LPG
Does anyone have any ideas as to what is causing this to happen

lpg is harder to ignite than petrol so any defect in ignition system shows up on gas before petrol

so maybe a change of the plugs would help

I changed my leads as i sprayed them with GT85 while the engine was running checking for air leaks and the spray caught fire, then i knew then the leads were fooked

Single point then :suspicious:

NEed top quality plugs and leads for LPG. Backfire means its running lean i think. Check to see if its fooked your air filter box, it did mine. Ive seen it recommended to replace the plastic box with the older steel ones if this keeps hapening. Is it on the changeover form petrol to gas?

Sounds familiar
This did help me
Although I am experiencing it more on petrol

http://www.landyzone.co.uk/lz/f10/p38-4-6l-power-loss-popping-125729.html

no it only happens on lpg

:welcome2:hi steve , dont know if this helps but here goes - have you had the lpg side serviced lately and has the filter been changed ? also check out your plugs and coil packs and leads . lastly if you have a local lpg agent ask him to check the trimming is ok , i personally have had all the above done recently alongside a full service on the car everything is running like a dream . maybe im a lucky chappie but have realised that if you look after these rangies then theyl'l look after you and behave. i have a 2000 4.6 v8 vogue with thor engine k80,ooo . hope above helps cheers mozz

just had to do all my plugs, they had deteriated but nothing had shown up. then suddenly iwas unable to run on lpg. changed plugs and its perfect now.

you can get the cable and software for most lpg controllers from ebay. if its a leonardo controller, like mine, i had a fault on one pcb inside the controller that wouldnt allow the stepper valve to open.

it sounds like a service is needed. if your happy to do it yourself then its pretty straight forward, a lead and software is essential tho to set up the lpg system. it is practically a carberetter(not very much different) and with the software you can tune it up in pretty much the same way you would a carb. you can get it something like by ear but it takes a bit of practice to do that so if your new to lpg then i would get the software!!


let us know what system it is(controller/computer) not the vapouriser. and i'll track the software down.

i have the Interface Kit,Software, Set of 11 adapter plugs for autogas systems
can help LZ Members in Essex

Came across this once on another lpg vehicle. (Forklift actually)

I was advised it could be condensation in the distributor.

The advice was correct.

Dried it all out with a hot air gun (at a reasonable range). Allwas fine after.

i got muddy boots on so popped in to tell ya ta burn the pile o ****e.:director::director::flame2:

Most of the lpg software has the ability to save a file for the ecu settings, go get it set up by your local lpg fitter get him to email you a file with the settings and use this if you ever need to reset, Mine can sometimes need doing if the battery goes flat but its only a five minute job to reset.