Ok heres my story. I have my pajero on LPG duel fuel its been on there the last 4months or so. No issues its been going great up till now. My Paj uses the 3.5 motor just mounted differently and different manifold etc pretty much the same as the sedan. I guess this would apply to the 3.0 engine or pretty much all.
Anyway cut a long story short my vehicle experienced a back fire through the manifold.
Basically the backfire took out the airbox and the airflow meter.
Before i converted to gas i was considering going injected gas but thought nah couldnt justify the extra grand for it.
Well today i am pretty much spewing i didnt go injected aparently this pretty much eliminates backfire issues.
Before anyone says leads plugs etc etc. All this stuff was changed before i did the conversion to play it safe. Even re sealed manifold gaskets etc cause of an earlier issue which was unrelated.
Anyway now the costs. I rang Mitsu and asked for pricing. This is where it gets intresting.
Top part of airflow box $157.00 there abouts cant remember the exact figure.
Airflow meter wait for it $742.00 for a replacement.
There is almost the 1k for injected gas.
I havent established the root cause why this occured but could be a crook lead or plug.
Now my concern is if i replace these parts the problem can probably pop its head up once again. Will be another costly excersise.
I will be chasing this up with Mitsu since they did my install hopefully they will wear the costs but some how i dont think this will happen.
In conclusion anyone thinking about going gas on their mitsu pay the extra now and go injected.
For the people who have already converted be aware that this can happen to you if you are running a mixer type setup.
Basically any savings made over the last few months have gone out the window.
How is the Paj running? Well on petrol it idles like crap mixtures are all over the place and lots of flat spots on gas its better cause it doesnt rely much on the Airflow meter.
Tommorow i will purchase some gaffer tape and seal up the airbox till it gets sorted.
In a way i consider myself lucky cause i know of one where it blew and damaged the bonnet as well.
If you can afford injected gas go for it. I will be replacing my system in the very near future. Prevention is the best cure.

Regards

ahh damn that sucks man!

Its happened to me a few times now too! I had a crack in the pipe between the mixer and the TB. And this caused it to backfire through the intake. Would blow all my cold air intake piping apart with a big loud BANG. I used to tape up the crack and it would fix it for a few months and then it would leak again and go BANG. So i've finally replaced that bit of piping and it was all good.

Then a few months later it went bang again. This time the bang was HUGE. I pulled over and popped the bonnet. And as i popped the bonnet i could see smoke coming from under it. So i looked under to see if there was a fire... nothing. So i opened it up and my intake piping had been all blown off the bends and all and was smoking. I pulled the MAF off and the top pipe for my CAI and decided to drive it home without the MAF. Unluckily when i drove off i heard a crunch and looked outside and i had driven over my new K&N pod filter because it had blown off and fallen on the ground. YAY! hahaha. Ended up my rear bank of spark plug were faulty.

It's all good now though.

P.s. i was EXTREMELY lucky for my MAF was ok. The honey comb on it was actually nicely mashed up. But a mate's dad went over it with a needle and pulled it all back out into a nice honeycomb pattern again!

wrexed03

thats a good example of how to get more bang for your buck
:bowrofl: :gtfo:

the main reason lpg systems back fire is its running lean

or the convertor is mounted in the wrong place

lpg is somthing that should be tuned every 5000 to 10000km as the diaphrams in the convertor and some mixers strech.

tuning of lpg is a very easy process providing that you use a gas analyzer most cars should be set at 2.0co and around 200 hydrocarbons per mil

you can also get 1 way valves to put in the intake it lets air pass in to motor but not a backfire in to the maf

best way i know to make sure you dont blow your intake box and piping apart, remove all the clips that hold your box together, just sit the top and bottom half in place, and then run an ocky strap around it to hold it together. when there is the pressure build up, it just stretches the strap, releases, and everything settles back into place.

go back to where you go it done though, if its only been 4 months, and you've kept up with any servicing thats needed doing, then it sounds like whoever tuned it ****ed up.

Well its going back on Monday since i have the day off. Airbox will be replaced. Airflow Meter will be repaired or replaced as well.
I dont beleive its the tuning cause i run an Air fuel mixture guage on it. So mixture readings have been consistant since day one. It may be a vacume leak who knows. I will let them deal with it.
At the moment i have taped it all up the top of the box is in a bad way nice huge crack through it and the plastic clips that hold it in place have broken away so its pretty stuffed.
The joys of LPG... If i have another re occurance i will just bite the bullet and get all the underbonnet stuff replaced with an injected kit and be done with it.
Regards

most of our work utes do this. we have resorted to putting pod filters on at this time. apparently it runs a lot better.. and no airbox to blow haha.. they are all going in for a service and retune in near future though, so well see how it goes.

Ey Joe our Paj did the same but ours back fired while the guys at Gas Research was tuning it on the dyno so they took fault and got things replaced

did your bonnet get damaged? ours now has a small bump the the box hit. the bax shattered but the maf was fine

did you check if all your vacum lines are still connected? no holes in the intake pipe?

Nah no bonnet damage but the airbox is smashed on the engine side and a nice crack on the top. Gaffer tape does wonders in situations like these lol.. I would have freaked if it stuffed the bonnet as well.

Regards

your not going to pay $700 for a MAF are you? Look on ebay and/or wreckers.. youll get one cheap enough

Nah no bonnet damage but the airbox is smashed on the engine side and a nice crack on the top. Gaffer tape does wonders in situations like these lol.. I would have freaked if it stuffed the bonnet as well.

Regards

lol ye dad almost passed out hahahahahaha