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lpg back fires

Discussion in 'Prado' started by toothless, Jun 10, 2017.

  1. toothless

    toothless Member

    there is no vacuum leaks in the system i had changed all the hoses and check the intake and there is no leaks
     
  2. toothless

    toothless Member

    so this is what is happening car sputtering on lpg when acceleration like it wants to back fire and on petrol takes of like a rocket
     
  3. GaryM

    GaryM Active Member

    Dont know anything about airod, but I assume theres an idle jet, and an acceleration jet. Couple of solenoids to operate them etc. Maybe Google the system and see whats what. The converters are pretty much a means to turn really cold liquid into gas to run and not freeze in the converter. Even stone cold, your coolant is boiling compared to the LPG. In the banjo shaped Vialle units, picture a pair of alloy mouse mazes, one maze (which is a side) LPG and the other maze/side coolant separated by a diaphragm. Gas can and does somehow gum up which can block jets. If its ever frozen, rubber seals/gaskets are probably toast (assuming airod use these).

    Put standard cheap spark plugs in it. If no better its not plugs, no need to replace fancy $$$ plugs just to find out. ID do leads anyway, unless you have good reason to believe they are new. And if it is the plugs just run the cheapies and replace at next change.

    A failsafe to stop airboxes being blown apart is a good tip but I just drill a hole and cover with a sticker next to the air box so I can inspect it (cleaned obviously, never had it fail). Im not sure Id want to with a 4wd though. Should be easy enough to grab a rubber bung or grommet and drill the right size then seal with sikaflex. Clark Rubber if you have one nearby has various bungs and rubber corks you could use as Muc suggested. They really can blow air boxes and tubes apart, was common on bbq Falcons that didnt have the spring clips on the box. Again though, 4wd, Id probably just risk the airbox if I couldnt get spring clips.
     
    Last edited: Jun 12, 2017
  4. Batts88

    Batts88 Well-Known Member

    I know it's different to efi but I had a carby GQ patrol on gas and was advised from a local mechanic to run it with the timing advanced a few deg. It never backfired or played up it ran well and I got good econ out of the old girl.
     
  5. toothless

    toothless Member

    cant really advance the timing on these no dizzy runs on coil packs but i have decided to get rid of it anyways its no good when i will start my touring next year when i get my camper trailer
     
    Batts88 likes this.
  6. muc the truck

    muc the truck Well-Known Member

    at the beginning of this thread mentioned people buy the cheapest lpg conversion . The don't understand or care what the difference is . They don't look at what they are missing out on . 99.9% the cheapest lpg installation quote wont have one of these LPG timing advance processers wired in . YES there is one for coil packs . Doesn't mater it its a crank sensor , cam sensor , hall effect ect there is one for all of them . Your selling , I under stand this but for those that are not . I suggest they ensure they have a advance curve processor on there ignition system to cater for the lpg spark requirement . Its the only possible way lpg duel fuel ever runs faultlessly with no noticeable difference between petrol and lpg . If you own duel fuel and you don't own one of these you have shot your self in the foot because your car is limping and not at its full potential by a long shot . There are other brands too . http://www.aeb.it/Products/Products/CatID/8/Timing_advance_processors
    or http://www.gncshop.com.ar/portal/company/#1476726150556-c21013f2-ca6f5e8d-2ffc but there are many more .
     
    Last edited: Jun 16, 2017
  7. toothless

    toothless Member

    i have one of those on the firewall
     
  8. toothless

    toothless Member

  9. typhoeus

    typhoeus Well-Known Member

    sequential injection is the way, Ive had an EMER system on a 3RZFE for about 4-5 years, Just recently it started running rough, so I bought the interface & program from Ebay, at about $50 and retuned it, actually, I used the auto configure and it did it automatically. now it runs nice & smooth. You cant tell when it switches over or when its running on gas
     
  10. muc the truck

    muc the truck Well-Known Member

    I believe that's the injector emulator to stop your ecu tossing fault codes on lpg . Its hard to say from the photo . some of these timing computers link to map sensor and I cant tell if its a hose from the map sensor or a harness from the injectors leading too it . If you have the timing computer there is normally 2 small box like items beside one another . one being the emulator
     
    Last edited: Jun 16, 2017
    toothless likes this.
  11. muc the truck

    muc the truck Well-Known Member

    Its the best of both worlds . It injects just the right amount and adjusts the timing to suit optimized lpg combustion . There is one thing how ever that's giving these a very bad name and for the wrong reason with customers never usually knowing the exact reason for poor performance , oil consumption and idle issues . Cowboys doing the cheap install - drill holes into the intake manifold for the injectors on the car . Metal filings go into combustion chamber and get caught in ring gaps , stops the rings turning and it scores bores , next you know they are using oil . I was all set to pay for sequential lpg injection but in Melbourne I could not find an installer that would take the manifold off a v8 land rover to drill the holes . I was going to hand them the manifold and re fit it my self then deliver the car to them but they insisted they didn't do any harm so badly I got the pooops with them because right at this very time my friend was rebuilding his 12 month old ford engine because of scored bores and stuck piston rings from drill swarf. As if LPG hasn't got enough tyre kickers without cowboys making it worse, they said the first thing we do on start up is give it some full noise just encase there is some filings in there (by this time both my hands hit my head in disbelief) . Old lpg taxies used to do 600 - 700 thousand kms on the draw through set ups but not many have reached that on the sequential before they changed over to hybrid prius . No issues with factory sequential installs nor any issues with off manifold drilling .
     
    Last edited: Jun 16, 2017
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  12. toothless

    toothless Member

    [​IMG]
     
  13. muc the truck

    muc the truck Well-Known Member

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  14. toothless

    toothless Member

    im still considering of getting rid of it or i may fix it i don't know but it does 27l per 100km on lpg and i only get 300km out of a tank
     
  15. Synchro

    Synchro Active Member

    Still cost effective to use LPG - cost per km is still better than other fuels. I drive mine around on LPG when commuting etc and switch to petrol when offroad keeping LPG as a fuel reserve.

    Make your LPG work and use it for everyday use.
     
    abw and muc the truck like this.
  16. muc the truck

    muc the truck Well-Known Member

    Exactly . what I did when I owned my v8 lpg/petrol disco was use lpg for daily use . On trips in very remote diesel only considered routes I would drive on petrol until there was enough room to empty jerry cans in the fuel tanks then drive on petrol to empty tanks , use lpg as a reserve and fill it all pack up when I can .

    He still has not fitted new spark plugs to see if that's fixed the running issues (miss) . Full consumption on pretrol seems bad as my disco never used more than 25 towing a combined weight of car and trailer of 4.5 ton . Empty with just passengers it would use 20-22 ltrs per hundred .

    Pretty certain if he spent a few dollars on the ignition the fuel consumption will easily pay for the repairs.
     
    toothless likes this.
  17. toothless

    toothless Member

    i know been lazy and plus working alot aswell and they moved my weekly pay to fortnightly now i did buy new coil pacs for it so its 10% getting there lol i also need to do the ball joints first as i dont want them to break because of the common problem my lpg does work except for a small few problems but the ideas that are getting thrown at me i will get it done mrs wants me to wait a year till its time for testing now and to see if i can sort it out i only had this prado for 1month now so it all takes time
     
  18. toothless

    toothless Member

    so plugs are replaced

    old ones
    [​IMG]

    [​IMG]

    new ones
    [​IMG]
     
    abw likes this.
  19. toothless

    toothless Member

    it idles so much better but i still need to take it for a drive
     
  20. Synchro

    Synchro Active Member

    Spend a few $$$ and get it looked at by a professional LPG place. Mine would not idle and it went in on a tune up machine for less than an hour. Identified a manifold air leak, leads breaking down causing odd firing and mixture issues. I fixed the air leak, but new plugs and leads and took it back and then he fixed the mioxture - etc - that was 7 years ago and is still running great. For about $150 all LPG problems fixed.

    Your plugs look fine for LPG use.
     
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