Hi, sorry I was a bit blunt last nite, it brought SO many bad memories, my 1st problem was a similar mis fire, it seems they are oh so fussy spark wise on LPG where they will run perfectly on petrol. I think a change of HT leads and coil packs eventually cured mine but the auto up shift was never as sweet on gas, I could always tell which fuel it was running on.
Once the mis fire was cured (sort off) the idle went haywire, often refusing to idle and without a clutch to save it and refusal to re start was a real problem meaning I had to get out and push ! Later the engine management system would shut down with no warning (lane 4 of the M25 is hard to forget) It just got worse and worse until there was no compression in certain heat ranges so I had the head re built with hardened valve seats (yes it did have flash lube fitted ) It then managed no more than 8,000 before it all started again so I gave up.
My previous Omega managed 200,000 on gas with no engine problems, plenty gas related hassle but was tolerable, The Lexus hardly managed 25,000
The GS cost me thousands more than I could have ever saved so I am sure Lexus are best left to burn the fuel they were designed for.
Good luck Tony
Thanks tony
I stopped a taxi driver (this was before I had it converted) who was driving a Lexus IS 200 which had been gas converted, he covered 100k with no problems the car has done in total 160k and still running strong. He has a Prins system which was out of my price range.