LPG Conversions

Back in 2005 when I bought a V6 Vauxhall Omega I decided to save on the running costs by getting it LPG converted. I started by contacting two local companies. One at Redditch and one near Worcester. Only the Worcester one replied to my emails, and their web site was informative and it looked like a reputable company. So I arranged a conversion the Autumn of 2005, using a Romano System N sequential gas injection (SGI) sytem.

I was not happy with this conversion!

People keep finding it and asking me about it, then I have to repeat the issues and recommend DIY.

Unfortunately the conversion took longer than expected, originally it was supposed to take a week but took seven days, this I was not too bothered by except for being transportless for the weekend.

The car ran fine on the test drive, but the coolant system did looked hacked around, it had taken three or so goes at getting a decent hot water feed for the evaporator, it ended up being fed from the behind engine pipes to the heater (which is the correct place on an Omega for hot water).

On the way home the car broke down on gas after using a large amount of throttle, but started OK a little later, this is due to the car cutting to petrol and the vapour pressure is too high for the injectors to manage.

Anyway it was OK for a while in the morning, but on the way to work it started running rough and switching back to petrol, I put up with this for a couple of days then took it back, the RPM feed for the LPG ECU, was suspected so was changed to a coil feed, it ran OK at the installers until on the way home it broke down.

During this changeover I was told that any more visits back to the installer would involve me being charged despite the system only being fitted for a few days. Even though the car would over pressure the system and drop to petrol I did not take it back as I was not welcome.

Anyway I investigated myself and found that the LPG system loom was routed next the the exhaust gas recirculation valve and when the engine was fully warm it melted the loom, shorting the RPM feed cable to earth. In the short trip home this had caused the engine to stop firing on two cylinders. I started by getting the cars ECU tested, luckily it was OK, but took nearly a week to organise, but the fault was in the DIS/coil pack I bought a new one for £79.95 with £7.50 P&P on 28/10/2005, but I was unable to fit it, so had to book it into the main dealers to swap it over.

Other issues found were, the LPG ECU had been fitted in the air box, this suffocated the engine and at full throttle robbed it of approximately 15 to 20bhp. The coolant circuit had various pipes cut and patched where hot water feeds were experimented with. I did (wrongly) make the assumption that the installer would know what he was doing.

In the mean time I moved the loom and wrapped it with tape and fitted a fuse to the RPM feed cable at the cars ECU end.

After nearly a fortnight my car was back, it ran OK provided I didn't use full throttle on gas, I managed nearly two months of this before I had an accident on the way to work when I hit a Diesel spill and rolled the car.

I managed to get removal instructions from the installer, but the body shop would not remove the kit so it ended up back at the installers and they removed the kit under protest and changing me as far I remember £150. I collected the equipment in the loan car and took it home, along with the tow bar. I had also by then viewed my current car and placed a deposit.

Since I had retained the equipment and bought a replacement car with a similar engine, the LPG kit was going to be reused. I decided I could not afford a professional refit and I was not happy with the original fitment, I did ask the installer, if I refitted the large parts could he help me finish it off and certify it. Basically he refused to help at all and also didn't want even to do a reinstall. I managed to repair the loom and work out what was what, I would email the installer asking what something was, and he would reply at length refusing to tell me.

It took me about a month to fully indentify the parts and to work out all the connections. I decided then to do a full DIY install due to the hassles of dealing with installers.

By early summer 2006 my new cars DIY conversion was ready - after repairing the kit and working out what the parts did it took me four Saturdays to convert the car. I had switched it to use RPM feed again and had mounted the components in better locations. I had a few heated emails with the original installer I requested the removal of the page about my car, the emails ended up with my final saying remove the page and do not contact me again, I received a rude reply and the page is still there.

So if you want a car which switches to petrol at high RPM, has the ECU fitted into the airbox just under the air filter, lots of water pipes cut and then threatens to charge when you want it fixed, here it is The page I asked to be removed I WILL REMOVE THIS PAGE WHEN THE LINKED PAGE HAS BEEN REMOVED

The over pressuring problem caused by petrol switching was minimised by cutting the injector duration during full throttle operation, unfortunately it leaves the car slightly weak at open loop operation, Autogas Worldwide advised me on this change.

I am not the only person to have had an issue with this installer - this chap did as well Here

Please note I will remove the mentions of the installer if Steven Sparrow from Go LPG removes the page featuring my last car complete with ECU in the air box and melting loom frying a £79.95 with £7.50 P&P DIS pack!

My final points are as follows. Do not take notice of installs on the web site, always contact the customer first, seriously consider DIY.

Vauxhall Omega V6 caveats, the hot water MUST be fed from the main coolant pipes behind the engine, the best one is the pipe between the block and the heater bypass valve. The only place for large ECU on the V6 is in the scuttle area so keep the drains clear. The best gas pipe run is following the petrol hoses. The evaporator is best mounted under the air box or under the front wing behind the wheel arch cover.

I hope this is interesting and if you want the links removed you KNOW what to do!

These pictures are of my current installation

This is an under bonnet view, I was accused of passing this off as my own, well this is the one I DIY fitted and has been nowhere near the original installer so it is my own work except for the pipework from the round gas manifold to the injectors, it was not worth redoing them and there is only one place to mount them if you are using through plenum straws. On the original install the evaporator was next to the power steering reservior - just under the yellow cap, on this car it is under the airbox out of view

When I DIYed, I supplied new 6mm pipe, new 8mm pipe, new filler, new vapour hose, new T Pieces, new hose from the pressure sensor to the plenum, evaporator and gas manifold, apart from the repaired loom all the wiring is new.

NOTES

DIS Pack/Coil Pack, this is the modern distributer less ignition style

Thanks to Mark for this explanation. He has explained what happened and why I needed to get a new one.

What you need to do is consider how an ignition coil operates for max effect.

What we are trying to do is get maximum energy into the iron core using the minimum current in a short period of time (in the case of DIS equipped V6, the coil is fired once every revolution). What we don't want to do is saturate the coil because at this point the energy will no longer be passing to the iron (as it is saturated and hence the term) but will be dissipated as heat in the coil windings.

By storing max energy in the iron we will then get max voltage from the secondary coil when the primary current is shut off. The coil setup has a permanent 12V supply on one side of the primary winding and the ECU switches the other side to 0V (chassis) to start the process of energising the coil. It tries to do this as late as possible so as not to hold the coil at saturation point for to long (in reality many of the integrated spark controllers detect the sudden rise in current at the saturation point and limit the current).

If we now consider a fault condition.

The Switched side (ECU controlled) of the coil is connected to 0V (chassis) permanently. The current will start to rise as energy is passed into the iron core until the core is saturated (this will only take a few miliseconds!). At this point, the coil is nothing more than a wire wound resistor and simply dissipates energy in the form of heat!

Now consider what is happening. The DIS pack has a primary resistance of about 0.5 ohms so the energy dissipated under such a fault is 288W!!!. Reality is that this figure will be considerably lower due to resistance of the wires etc but, the primary winding of a coil will NOT survive this fault scenario!