LPG

[henrym3]

Car goes in tomorrow to be looked at as it is reluctant to start on LPG ie starts dies, starts dies, its fine on petrol and sometimes reluctant to switch over. don't know enough to fiddle, but seems like a pressure or lack of it problem.

[graemeX5]

Hi

I would thought lezmtaylor would be the person to ask/ pm as I know he has hag LPG on his X5 for a long time and doesn't seem to have had any problems.

From what little I know I thought you were supposed to start car on petrol and then when the car is warm you switch over to lpg but I may be wrong.

Graeme

[PokenH00D]

I had LPG on my E61
You need to start on petrol and drive for a short while to get some heat into the engine so the evaporator can work it's magic. At this point it should switch over without any issue.
If it's not doing this, I would see when the last annual service was done as the symptoms you describe are what you'd get if it was desperate for an LPG service and new LPG filter.

[Imy]

what system do you have??

All LPG should start on petrol and turns to LPG once warmed up. I had a BRC system and I know Prins do this also (2 of the most expensive set ups).

You shouldn't be starting on LPG. If you have a switch, try starting the car on petrol, drive around until warm then switch it to LPG and see what the result is like.

I do miss my LPG X5

[henrym3]

Don't wish to be rude but I'm not an LPG virgin, I know it starts on petrol when cold, below a set temp, but if you get back in the car while it's above that temp, it should start on LPG. It should switch between the systems automatically like it has done for the last 2 + years. As for servicing it gets done as recommended every 7.5k, probably a bit OTT but it's only £30 for filters and diagnostics check. Anyway, still not fixed, the diagnostics is showing voltage spikes downward as low as 9.5 volts with the engine running and alternator showing charge of 13.8v. So next step apparently is to check all electrical connections to/ from LPG ECU, that's going to be difficult as the system is working NEARLY 100% of the time.
Least of my problems, arrived to pick vehicle up and it has a big dent in a front wing, "It couldn't possibly have happened here sir" I can assure you it bloody well did. Stalemate situation. Do any of you ever take anyone at a garage round your vehicle and point out that it's NOT dented anywhere? The place is surrounded with cameras, their own and 3 other businesses, not one of the things are working. Soooo pissed off.

[kkx5]

Is should never start on LPG, no matter what engine temp...

[henrym3]

Now that is interesting, maybe I need to change my LPG fixer, I assume kkx5 you are clued up/expert on this subject, so I should be chasing a petrol problem or should I say a warm engine petrol problem, as starting from cold is always fine? Out of interest how long after hot start does it take to switch back to LPG.

[IanP]

My gas system was not a high end one, but even if you stopped the engine hot on gas, and started immediately afterwards, it would start on petrol. Change back to gas would be a few seconds later. I could force it to start on gas but only did it once .....
On mine, the heat exchanger for the gas system was a little remote so would cool fairly quickly. As the gas system takes its temperature readings from this point it could take a little time for it to start.

[kkx5]

[quote="henrym3"]
Now that is interesting, maybe I need to change my LPG fixer, I assume kkx5 you are clued up/expert on this subject, so I should be chasing a petrol problem or should I say a warm engine petrol problem, as starting from cold is always fine? Out of interest how long after hot start does it take to switch back to LPG.
[/quote]
Warm engine issues...but you need to tell us, what lpg system on yours? II, III, IV, V gen?

[X5-D-Sport]

Some thing I learned the hard way, was that LPG is not as clean a burn as Petrol / Diesel.
The lead/substitute in fuel allows for a cleaner more even burn, where as a gas is a very ragged/unpredictable combustion.
LPG & Hydrogen converters have a habit of creating micro-fractures in the piston liners/head gasket edges & cylinder head material.

This info is not generally made clear, but may be a consideration. Several colleagues with Big Engined Saloon BMW vehicles have suffered the same after they have bumped up 60,000 on LPG & needed an engine rebuild.

Generally in the automotive industry, Diesel engines use better metallurgy due to the extreme pressures & knock issues with Diesel engines to prevent piston liner cracks etc, where as Petrol Engines are a softer engine generally.

It may be worth weighing up the trade off with engine damage & £££ saved with LPG.
Several people I knew in years past used house hold heating gas for vehicle use & saved a fortune in fueling costs... but I'm fairly sure it was not strictly legal though.

I'd like to think the road use LPG has some sort of lead substitute in the mix these days to prevent engine damage, but I'm sure some one here will have the answers to this one...

[kkx5]

....yyyy, all my cars are, were, will be on lpg. Fiat punto 1.2 350.000 miles on lpg, never had an issue, all bmw with over 100.000 on lpg, never an issue, seat altea, seat toledo over 100.000 never an issue, audi a6, a4, vw passat, vectra, escort, the list can go and go....A good lpg system fitted  by lpg expert will never ever damage the engine

[IanP]

Have to say that when I took my 4.6 apart it was in good condition internally, after 40 odd thousand miles on gas. Except for the cam chain tensioner obviously

[X5-D-Sport]

I wonder if there is an some sort of Lead type additive  in the current available Road LPG to prevent the pinking/knocking & rough burn characteristics of gas ?

[henrym3]

System was fitted by Douglas Park BMW in 2013. It is a ZAVOLI with 2x pressure reducers fitted in series, has an 85ltr tank. The receipt says it cost an eye watering £2110.55.

[kkx5]

Top notch LPG system. Search for engine issues. Crankshaft sensor?