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| -GAS-MAN- |
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Gday everyone; after my crazy idle problem was solved, which was caused by the map sensor hose lose from the runners, now every second of third time i start the car you hear a light *pop* (and as the heading suggests) off comes the map sensor hose.
So i reach out to you for the answer to: Too much initial pressure on startup for some reason or The little rubber grommit / fitting is getting old? I dont want to cable tie the oldy on incase the map sensor gets too much pressure and something goes wrong, although i assume that this is not the case. Cheers big ears' Matt
_________________ it can be fast and cheap,but it wont be reliable |
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| joolz |
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Sounds like the valves are open when they should be closed causing pressure instead of vac in the manifold!
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| Redford |
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joolz wrote: Sounds like the valves are open when they should be closed causing pressure instead of vac in the manifold!
spot on joolz, just get a mechanic to check that the crank\timing chain is aligned with the cam or you could have some expensive valve issues. i don't think its the head gasket and would only happen when the butterfly is closed on idle.
_________________ Speed Safely! |
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| -GAS-MAN- |
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Awesome! Thanks, will do, for the time being i wont cable tie the hose on to stop it popping off?
Thanks alot! Again 
_________________ it can be fast and cheap,but it wont be reliable |
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| Redford |
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i got a small ring clamp on mine to stop it slipping off but only cos the hose was slightly larger than the map sensor inlet pipe.
poping off isnt good tho, is it a tight fit?.
_________________ Speed Safely! |
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| -GAS-MAN- |
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Yeah its a tight fit, probably not as tight as it was from factory, im replacing that first and seeing whether it still happens, just because its so much cheaper!
Matt
_________________ it can be fast and cheap,but it wont be reliable |
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| Redford |
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just take out all the spark plugs, grab a screw-in type compression guage ($40 from supercheap) and check each cylinder. it only takes about 15 minutes.
write down the highest reading along with cylinder number, each cylinder needs to have the same pressure (usualy within 5psi).
_________________ Speed Safely! |
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| gogetta |
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Redford wrote: just take out all the spark plugs, grab a screw-in type compression guage ($40 from supercheap) and check each cylinder. it only takes about 15 minutes.
write down the highest reading along with cylinder number, each cylinder needs to have the same pressure (usualy within 5psi). i have never found a car that has had compression that close on all cyls.. even if it was down 30 it should still run fine...just depends on how perfect u need your motor to be.
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| gogetta |
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GAS_MAN is your car on LPG..
if it is then its backfiring...check the usual suspects
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| -GAS-MAN- |
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Thanks for that, i remembered i had gapped the spark plugs with a 5cent piece (just to see how it would run), is probably that.
Also i ran low on petrol, now with $10 premo in it, it wont run 
Probably a filter or a line somewhere. Oh well, lpg is good enough, just have an excuse to lighten the car by 20kg's now and get it dyno'd to lpg. Thanks again! Matt
_________________ it can be fast and cheap,but it wont be reliable |
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| Rick's EF Fairmont Wagon |
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I have had occasional backfires on gas like that and the hose pops or the PCV valve hose. Make sure you have the Metal PCV valve for gas engines. The plastic one has been known to crack and get stuck in the valvetrain. I generally start on petrol to avoid trouble but sometimes I start on gas when hot and then sometimes i get worse backfires when hot days and parked at the shops etc for 5 mins.
_________________ BF3 Egas XT Wagon |
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| -GAS-MAN- |
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Thanks Rick, ive gapped those plugs back to stock measurements, if it happens again ill go get a metal one.
Matt
_________________ it can be fast and cheap,but it wont be reliable |
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| 66 coupe |
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gap the plugs to 0.8 - 0.9mm for gas, a 5c coin is not the way to do it, also how old are the leads, gas requires a lot of ignition energy so if the leads are old / out of spec then it will backfire through the intake and cause what your describing.
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| Redford |
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Gasman, was it backfireing through the inlet like rick & getta sugested?
ive had problems recently with my EB running on gas, but its more like a "BANG!!!" not a pop. ive never heard anyone using 5 cents to gap plugs, i just checked and its 1mm so its not that far out, lol : )
_________________ Speed Safely! |
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