Any LPG gurus here?

[Jimmycrackcorn]

Just gotten an XJ8 in at work that happens to have an LPG kit, it's runs well etc so I know it's good.

My question is I'd love to fit it to my 3.0 v6. Is it just a case of removing the extra two LPG solenoids or is it much more involved? I would replace all wiring and hoses/piipes if it was done.

[TataBobu]

Imagine doing the same for a petrol injection. It wouldn't work. I mean it's not a bolt-on job.

On a sunnier note, you'd have to find the LPG ECU, see if it's programmable to supply a 6 cylinders car, and then you might be able to pull it off. As far as I know it has to be programmed, usually the LPG ECU gets the injection timing, lambda and some other informations from the engine control unit.

 

EDIT: not a guru, just a somewhat experienced user.

[Jimmycrackcorn]

I thought that might be the case, if it comes to it I won't have to buy a tank as the kits tend not to come with them and a new 6 cylinder kit can be had for around £250.

[TataBobu]

I don't know how it's regulated over there, but here the LPG tank has to be changed every 10 years. I just changed mine, and it was 400 RON (that would be around 65 pounds).

[Jimmycrackcorn]

Same here with the 10yr rule. I've only had a quick glance and it looked newish. I'm really only planning on having it a year and I wouldn't make back the cost of fitting a new kit within that year. If it was something I'd planned on having long term then I'd go down the new route. 

[mat_the_cat]

You will still need to program the gas ECU (depending on what make influences DIY software availability), but going from 8 to 6 cylinders itself won't be a problem. The gas ECU takes its signal from each petrol injector, so without a pulse from cylinders 7 and 8 it won't fire the corresponding gas injector...

 

Personally I'd be more inclined to get a new kit unless you have plenty of time to remove. Any issues with fitting you'll be better off with a new system, hopefully with support from the supplier - Tinley Tech are very good.

 

Be aware that it may not just be the gas system to swap over as well, I've heard of a few Jags which throw a fault code for the petrol fuel pressure when running on gas (i.e. petrol not being used so pressure ramps up), unless a bypass pipe is fitted to circulate petrol back to the tank.

[TataBobu]

That could be solved by a secondary fuel pump relay, normally closed, in series with the current car's own. And that relay's coil should be powered by the LPG relay, so when the car runs on LPG the petrol pump would be cut out.

[Jimmycrackcorn]

There's plenty of the v6's around on gas and there's a fella up the road who's fitted kits to a few of our customers. The intention was to fit it and get him to test and set it up for me.

[mat_the_cat]

That could be solved by a secondary fuel pump relay, normally closed, in series with the current car's own. And that relay's coil should be powered by the LPG relay, so when the car runs on LPG the petrol pump would be cut out.

 

But then you get the risk of petrol sitting stationary in the fuel rail above the engine,getting hot and gumming up the petrol injectors...

 

It's quite a well known issue, so anybody who's installed one before should be aware of it. Just wanted to point out it may not be quite as straightforward as it seems!