Quote Originally Posted by niky View Post
I'm doing testing and observation right now... I've been discussing this (offline) with Ghosthunter at length, and we're theorizing it has something to do with vaporizer pressure and temperatures at idle.

When the car is idling, there will be times that the thermostat will close as the coolant temperature gets lower... this will cause a change of flow to the vaporizer, and a change of vapor pressure... or... if the car just gets cooler in general, this may cause the vapor pressure to drop... will try to do instrumented temperature testing... it might be that for people with this problem, a second vaporizer or an upsized vaporizer would help... discussed with Speedlab also the possibility of an electric heater on the vaporizer, but that's an idea for the future, for customization.

I notice the loss in performance, too... but after a few minutes of hard running, the power comes back. That's why I suspect it's a loss of vapor pressure due to cold conditions (at least on my car).
Hi niky. I couldn't help commenting as I have been tinkering with my own LPG cars for more than 3 years.

May I know, what seems to be the problem with your car? Is the idling rough and the idling speed changes off and on?

I have had quite a bit of experience with my own cars, both venturi mixers in regard to finding a consistent and stable idling speed, esp. with air-con compressor.

Just a comment on your theory, if you don't mind. The heater water circuit does not share pressure with the vapor regulator chamber, it merely provides heating to a coil located in the vapor chamber.

Consequently, the diaphragm that regulates the vapor pressure is not affected directly or indirectly except perhaps by temperature though I believe the diaphragm does compensate for that also.

What in fact affects the vaporiser diaphragm is the vacuum pressure from the intake manifold which moves the diaphragm against the spring that holds back the vapor. Perhaps a check on your vacuum lines and intake manifold for vacuum leaks might solve the problem. It may take a while but this ultimately solved the problem for me.

The other place to look is your ignition system. Petrol is more forgiving of a defective or substandard spark, but not LPG. We need a clean strong spark to fire that thin gassy mixture! Any weakness in the system, will result in rough idling or even loss of power.......

hope that helps,

steve