Hi. I have recently had a Tinley Tech LPG conversion kit fitted to my 4.2 litre 1984 XJ6. It has been running faultlessly for several thousand miles with no trouble. In that time, it has experienced three backfires, the third of which blew a seal in the airflow meter causing the car to break down. I have driven it for a further 60 miles and it has backfired once again. We have replaced the colil and distributor cap. I think the problem is caused by running it on gas. Has anyone experienced this problem? Can anyone advise me as to how to resolve it?
LPG
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LPG problem
Hello sorry to hear your having a problem with the lpg system.
Do you have the old single point injection or is it a fully sequential
system? If its the older type then the intake manifolds will have an air and lpg mixture in them so, accurate timing of the engine and correct function of the ignition components will be vital to prevent unintentional ignition of the gas inside the manifold. This could result in the damage you describe. Check ht leads for stray sparks and manifold nuts/studs and gaskets for leaks as these are all possible sources of ignition.
If you have the fully sequential system i recomend you contact tinley tec as it is rather more complex and may require proffesional attention. I hope this is of some help to you.
P.S remember that lpg burns hotter then petrol so make sure the cooling system is properly maintained to avoid problems.
Do you have the old single point injection or is it a fully sequential
system? If its the older type then the intake manifolds will have an air and lpg mixture in them so, accurate timing of the engine and correct function of the ignition components will be vital to prevent unintentional ignition of the gas inside the manifold. This could result in the damage you describe. Check ht leads for stray sparks and manifold nuts/studs and gaskets for leaks as these are all possible sources of ignition.
If you have the fully sequential system i recomend you contact tinley tec as it is rather more complex and may require proffesional attention. I hope this is of some help to you.
P.S remember that lpg burns hotter then petrol so make sure the cooling system is properly maintained to avoid problems.
lpg system
Hi just joined jec this month i have got lpg system on my xj40 1993 it is a multi point system and runs smooth at the moment. 6mthd ago i had a jeep grand cherokee and it was lpg single point did the same to me kept back fireing and was told that the 4lt does not like single point lpg system and advised to change to multi-point however i got rid of it and bought this nice jag hope you get problem sorted billy
Hi There
LPG on a car like that is almost certainly single point open loop. I.e. Gas injected with air through the air intake. Open loop means there is no sensor in the exhaust as yours is a pre-catalyst car.
Firstly, this is not likely to be a problem as such with the LPG system. LPG systems like the above are VERY sensitive to ignition timing, and the condition of all relevant sensors. While some may be slightly worn and you may not realise this running on petrol, running on gas, the worn components become far more apparant. I would suggest replacing, and checking all relevant ignition components and air meter, and also seeking the advice of an LPG converter.
Ultimately, however, the single point LPG systems are not perfect, and can cause backfires which can be damaging. The only way to avoid this that I m aware of, despite contrary claims by LPG converters, is to inject the LPG direct into the inlet manifold in a mulit-injector system. This is much more sophisticated and will allow the car to run much better. This is however more costly to fit.
My X300 XJR has a multi-point LPG system on it, and has run perfectly for the last 3 years and 30K miles...
Cheers
Pete
LPG on a car like that is almost certainly single point open loop. I.e. Gas injected with air through the air intake. Open loop means there is no sensor in the exhaust as yours is a pre-catalyst car.
Firstly, this is not likely to be a problem as such with the LPG system. LPG systems like the above are VERY sensitive to ignition timing, and the condition of all relevant sensors. While some may be slightly worn and you may not realise this running on petrol, running on gas, the worn components become far more apparant. I would suggest replacing, and checking all relevant ignition components and air meter, and also seeking the advice of an LPG converter.
Ultimately, however, the single point LPG systems are not perfect, and can cause backfires which can be damaging. The only way to avoid this that I m aware of, despite contrary claims by LPG converters, is to inject the LPG direct into the inlet manifold in a mulit-injector system. This is much more sophisticated and will allow the car to run much better. This is however more costly to fit.
My X300 XJR has a multi-point LPG system on it, and has run perfectly for the last 3 years and 30K miles...
Cheers
Pete
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