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vnlexcen
Learner
8 Posts
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 Posted - 14 Mar 2012 : 3:42:37 PM
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it never used to do it when i first got the car but now when i put my foot down a little to hard the car backfires on lpg and sometimes stalls at standing takeoffs. iv checked the plugs, leads and the coils and i just dont know what else i can do.. anyone got any suggestions what it might be? 
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Mechknight73
National Driver
1001 Posts
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Posted - 16 Mar 2012 : 12:21:29 AM
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| Check around the rubber sections of the intake on the LPG system. What I mean is, the flexible rubber tube immediately behind the air flow meter may have a leak. I can vivdly remember seeing this once on a Land Rover Discovery runnning on gas. The airflow meter is the equivalent to the throttle body on a carburettor. It monitors how much air goes in and who much fuel is mixing with it. If there's air coming in behind that point, it will confuse the ECM, making it backfire and possibly stall, much like what's happening to you. The backfiring is to do with ignition timing, the stalling is likely to do with the ECM's inability to change said ignition timing quickly enough or far enough to cope. |
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vnlexcen
Learner
8 Posts
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Posted - 16 Mar 2012 : 10:03:04 AM
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| that sounds exactly like whats going on mate thanks for the info. she did it to me this morning backfired twice and stalled when i took off and almost got t-boned. was a close call. but ill check it all after work and thanks again bud cant afford a mechanic on my wage so i do it all on my own from what my father taught me |
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Mechknight73
National Driver
1001 Posts
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Posted - 16 Mar 2012 : 12:47:46 PM
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| I may be wrong, but if I am, no doubt others will be around with other suggestions. On LPG, it's the most likely though |
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vnlexcen
Learner
8 Posts
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Posted - 16 Mar 2012 : 8:53:28 PM
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| was it the hose coming from the intake manifold to the throttle body? if so i replaced that cause it had a kink in it and also trimmed abit of a small skinny hose comeing into the side of the elbow attached to the manifold. it had a small split in it. still backfires but lets me push down a little harder on the throttle before doing it. so i think it might be the gaskets between the elbow-manifold needing replacement as i took out the bellmouth a few days ago and now there is a squeeling noise comeing from there so i think that will be the only problem now im hoping |
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Mechknight73
National Driver
1001 Posts
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Posted - 17 Mar 2012 : 12:25:54 AM
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| That is the one I meant. Sounds as if you still have a leak, but you can only eliminate them one by one. When you replace those gaskets, use a good quality sealant to make sure it can't leak, but keep the sealant away from the inside of the throttle body. While you're at it, check any nearby vacuum hoses for leaks, just to be sure. Also, make sure the clamps holding it together are firm, it's a possibility as well |
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vnlexcen
Learner
8 Posts
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Posted - 17 Mar 2012 : 12:30:46 PM
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| yep yep cheers mate just gonna get some prices today |
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Mechknight73
National Driver
1001 Posts
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Posted - 19 Mar 2012 : 12:01:38 PM
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| In case your father never taught you, if the price of gaskets, such as the ones around the airflow meter are a bit pricey to you, buy some gasket paper and remove the part you need to make a gasket for. Using a ball peen hammer, gently tap around the edges and holes of where the gasket goes. This will punch the outline into the paper. Handy when the gasket you want is unavailable or obsolete. |
Edited by - Mechknight73 on 19 Mar 2012 12:04:02 PM |
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vnlexcen
Learner
8 Posts
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Posted - 22 Mar 2012 : 10:59:15 PM
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| yeah thats what i ended up doing mate. lazy guy at supercheap couldnt find them in his computer. stopped the whining coming from there but still a backfire.. but iv elimnated it down to one tiny little spot so going to fix it tomorrow and see how that goes |
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vnlexcen
Learner
8 Posts
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Posted - 29 Mar 2012 : 12:50:54 PM
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| fixed all the air leaks n little holes in exhaust.. but still backfires. i got told to replace the o2 sensor near the start of the exhaust and if that dont work i dont know what else it could be :( |
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Mechknight73
National Driver
1001 Posts
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Posted - 30 Mar 2012 : 7:45:24 PM
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| The problem is 90% certain to do with ignition timing. Anything that backfires is usually doing so because the plug is firing before or after when it should be. Coughing and spluttering under load, I'd say fuel, or the plug leads are shot. Not firing on all cylinders is the ignition module rooted. I'm unsure myself, but will ask some people more learned than me |
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Michael
Starting in the driveway
2 Posts
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Posted - 04 Apr 2012 : 11:46:28 AM
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| Will be plugs and or leads. Ran VN taxis on gas, Falcons the same. Pleads good for about 50k, plugs maybe half that. |
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backfire on lpg when putting my foot down
