Smelling unburnt lpg!

[terrain patrol]

Why do I continually have a strong smell of unburnt lpg from the tail pipe at idle,is it normal or is there something sinister going on?Running aTB42 with impco gas system ,90litre tank and get around 340K's per tank highway and 270K's city driving:confused:

[vk2icj]

Mine always has a strong odor as well. I get about the same (gasp) economy in mine too. If you can use economy and Patrol in the same sentence.

[jg1982]

My LPG vehicles seem to smell a lot worse if they're idling too rich. Might be worth checking mixtures.

[GQFourby]

They do add something to make it smell, otherwise you wont know if its leaking. They all smell like that, you notice it more in the CBD though where there are heaps of taxis.

[minisman]

From what i know you will always smell it a little bit. If its quite strong (and you are getting bad economy) you may be running a bit rich. Could be time for a tune, or attention to your ignition ciruit. LPG needs a good strong spark to run efficiently.

Another thing with LPG is that it relies on hot coolant flowing around the converter to "atomise" ( i think) the LPG. when your collant is cold the LPG wants to stay liquid in the comustion chamber and wont burn. So if its just rich when engine is cold that is the reason.

[tazwegion]

I believe that they're tuned to be a little rich @ idle so as to counteract a lean LPG mixture higher up the rev range, using your EFI throttle body for gas is a compromise in terms of performance & economy especially when you consider that it's also got to run with your Petrol system too :D

AFAIK a better regulation of LPG is achieved with a Gas injection system, the GasResearch carby (LPG only) works a treat too though obviously it's not intended for dual fuel systems :thumb:

[terrain patrol]

How do you know when the mixtures are right?Can I do it myself or do I need to use an exhaust gas analyser?

[tazwegion]

An exhaust gas analyser would be the way to go however It's not something I'd personally recommend anybody mess with... take it to an accredited LPG mechanic to tune (if you feel the need) :)

Remember that the ignition advance settings are also compromised as LPG likes an even further advanced setting than petrol prefers, so your Patrol is tweaked for either LPG or fuel economy but NOT both :(

[terrain patrol]

Cheers thanks for the info,I think that there is something in the lpg not atomising properly as I suspect that someone has removed the thermostat.Checking it out this weekend as the bloody thing just doesn't seem to get hot!

[terrain patrol]

Eureka!!!The bugger had no thermostat fitted.Since fitting, the smell once the engine is warm has virtually dissapeared and an annoying occasional miss has also dissapeared.
Thanks Very Much.

[ferozakid]

this has been a great thread, it just told me about all the problems i've ben having with my ute, thanx heaps guys