Serious Lpg problem - please help

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d_j · #1 Post by **d_j** » Thu Nov 02, 2006 8:29 am

Hi all, been having some bad problems with my new lpg system. Ever since it's been installed I've had a problem whereby the car (BMW 323ci Auto) cuts out and stalls sometimes when pulling away from a standstill - this only happens in lpg mode. I've taken it back to the lpg place who have tried to fix it twice now, with no effect unfortunately. It tends not to happen once the car has been running for 30+ mins and is properly warmed up. When it happens, my engine light comes on to tell me exhaust emissions have deteriorated (?). However, over the last two mornings, presumably because of the cold, the problem has become a lot more serious. Even after I've gone about 5+ miles the car has cut out on the motorway once (which was very dangerous), and this morning it nearly cut out at 60mph (the engine light came on again and it started to splutter) and after that had happened I switched back to petrol immediately to stop it dying, but even on petrol then it ran very spluttery and noisy until I eventually pulled over and re-started the engine (after which it was fine again, in petrol). It's obviously temperature related in some way, but I need some advice/knowledge to take to the installer so I can get this fixed!

richy_boy · #2 Post by **richy_boy** » Thu Nov 02, 2006 8:39 am

I'm no installer, but it might be water temp / vapouriser related. i.e. because of the cold air your water temp is much lower, especially on a motorway. Your vapouriser uses hot water to turn the liquid LPG into a vapour.. if it's not hot enough there won't be enough fuel to inject to keep your engine running. I dunno what the solution would be as I'm not an installer, but that's my wild, unprofessional, unqualitied opinion on what MAY be happen. Maybe the installers have connected up to the wrong water outlet in the engine bay? ... rich awaits someone who knows what they're talking about. Rich

chobson · #3 Post by **chobson** » Thu Nov 02, 2006 10:22 am

Daniel, I have a BMW 523i auto and have had similar problems, now hopefully fixed. The fixes which eventually stopped the problems were: 1. The kit originally fitted to my car was not the right one. On my engine there is an air bypass sytem which allows additional air to enter the inlet manifold under certain conditions. The firm that fitted my kit had to fit some "straws" to position the lpg injectors closer to the inlet valves. 2. After nearly 12 months I started experiencing stalling and bad starting problems. This was caused by a build-up of wax in the vapourizer. I had the lpg system serviced and this fixed the problem. 3. My car has always (until recently) hesitated as I set off. This problem seems to have been cured by re-positioning the vapouriser. It should be fitted so that the spindle is horizontal and at right angles to the direction of motion of the car. NB this is a PRINZ sytem which is in my view a good sytem and I've had some good support from Alternatech the importers.

bob · #4 Post by **bob** » Sat Nov 04, 2006 4:52 pm

Fit new thermostat. I suspect you may have a bit of icing due to the expansion of a liquid into a gas. The stat controls water flow to the rad so outside temp should make no difference. Cold weather and the stat will close up a bit. Stats fail safe -- open. They are cheap and a service item which is often over looked

simon_egas_uk · #5 Post by **simon_egas_uk** » Sun Nov 05, 2006 11:19 am

Hello Daniel As Robert says he is "no installer" and sometimes I think it would be more beneficial if he left some of the technical explanations to members of the forum who do have the technical and practical experience. I Hope Robert takes this comment in the spirit it is intended, quality not quantity is helpful. That said he has almost hit this one on the head and if not this advice would apply to many temperature related faults. Your problem is certainly temperature related that much is obvious. You have also said that this is an automatic BMW. You have not said which make of kit it is but to a point at this stage it is more helpful not to blame the Kit. I guess and hope that it never the less is a sequential multi point injection system. Your problem could be hot water flow. Robert mentioned Thermostat and that should be easy to establish, is the temperature gauge on the dashboard showing normal temperature whilst all these issues exist? If not replace it. Next where is the vaporiser specifically located? We always suggest that the highest point of the vaporiser should be no higher than the bottom of the Top radiator hose, this makes sure that the vaporiser is defiantly in the flow of the water jacket. Last where is it piped to? Usually on a BMW there are 3 pipes going into the cars heater, one of them comes directly from the engine block this is the first to T the vaporiser into. The other 2 pipes go to a double solenoid valve block we do not touch these. At this Valve block there are 3 pipes the 2 we have just mentioned and a third pipe, it is this third pipe that the vaporiser should have its other connection T’d to, this pipe goes directly to the engine. I am sure that if you check what I have said above that your installer will put right anything that is not correct. Simon

simon_egas_uk · #6 Post by **simon_egas_uk** » Sun Nov 05, 2006 11:20 am

Part 2 The other thing that is temperature related is any temperature sensor fitted in the vaporiser or elsewhere in the kit, again your installer would be able to check this or simply substitute if it were potentially the problem. Charles writes in his item 1 about Straws. Do not shoot me but providing your installer has put the gas injector nozzles as close to the petrol injectors as possible (within 10mm) this would not cause the temperature related issues we are talking about. It is true that BMW along with other manufacturers use variable length manifold technology to improve torque response but BMW usually does this within the plastic manifold and it is about 40 mm from the cylinder head to engine block interface where the two inlet tracts join. Again your installer and the supplying dealer should be able to verify this and help if required. Simon

bob · #7 Post by **bob** » Sun Nov 05, 2006 5:25 pm

Check that the vaporiser is getting warm by touch and how many miles it takes. For ice to form the temperature must be below 0 deg celius. This means that the vaporiser only needs to be warm. Modern car have quick warm up times I would expect the vaporiser to be warm after 2 mins running from cold. Check out the heater. If the heater is showing signs of warmth in 2 mins and the vaporiser is not then you have a circulation problem. There are two types of heater systems Air blend and water blend. Airblend have no water valve so there fore the position of the vaporiser connections are not so important. Water blend systems have a water valve so it is possible to plumb the vaporiser in so that when the heater is turned off so is the water supply to the vaporiser. Worth cracking the upper most water connection to the vaporiser to see if there is an air lock- engine cold not running. Because modern cars do have low radiators. Modern cars means anything made after say 1960.