I have been running my 1991 LS400 for 3 years on L.P.G. with only occasional use of unleaded fuel when L.P.G. has run out. The engine has now developed a persistent misfire. My local Lexus dealer has diognosed a burnt/sticking valve. He says that he has had 3 others diagnosed with the same problem, all of which have been converted to L.P.G. Before looking at very expensive surgery, I am going to try running on petrol with an upper cylinder addative(redex or similar) to see if this cures the problem. If this doesn't work, does anybody know where I can get the cylinder heads renewedwith new valves etc. atg a reasonable cost? My local Lexus dealer currently charges around £80 an hour. Help!!!
P.S I live in Wales, near cardiff, but am prepared to travel a reasonable distance.
Jeff.
