hi
i own a lexus ls400 1992 with a gas/lpg conversion,running on petrol is fine but when i switch to lpg the engine idle speed reduces then cuts out.When i`m going along its fine on lpg but when i come to stop the engine cuts out and wont start again till about 30 seconds later?I was told this was to do with a lambda sensor but this has not cured the problem.i`ve been told to put the car on a diagnostics machine to find out the problem and i`ve also been to a lpg conversion place which costs the earth for their services,and still the car doesnt work properly.I`ve been told the conversion kit is italian made to which i beleive is good.Has anyone got a cure for this !
Full Version: Lpg Ls400 Problem
Lexus Owners Club > Lexus Models > LS 400 / Lexus 430 / Lexus LS460 / Lexus 600h > Engine & Transmission
Is it a single or multi-point system? What's the manufacturer?
As eXOBeX says knowing what system you have, single point or injection and the make.
It is virtually impossible to diagnose problems on a forum unless you want to just keep replacing things,
But...
What did the lpg place think was wrong?
Did they replace anything?
Did the lambda make any difference at all?
Pete
It is virtually impossible to diagnose problems on a forum unless you want to just keep replacing things,
But...
What did the lpg place think was wrong?
Did they replace anything?
Did the lambda make any difference at all?
Pete
If it's a Romano multipoint system I've got the software and the programming cable 
If it was mine, first things I'd do:-
Save a copy of the config
Check the diagnosis page for anything obvious (it just shows if the injectors are running OK)
Update the firmware to the latest version (for the Romano it's 33.0)
Perform an auto-calibration
Save another copy of the config
The last two steps this weekend solved a "tripping over to petrol under high load and high RPM" issue that's always been there, and the car feels a bit nippier too.
Mine was fitted by Phil Price, he does autogas conversions and runs a rally school where all the cars are gassed. Gave me his old programming lead too - top bloke! Don't know how much he'd charge to inspect/repair/replace your system, but like I said if it's a Romano Sequential Vapour Injection system I've got the lead and can lend it to you - just add car and laptop with a serial port! Worth checking out before shelling out. You can also check the gas and reducer (vapouriser) temperatures using the software, this could highlight issues such as an airlock in the car's cooling system (although if this is the case a Romano system will probably stay in petrol mode as it'll know that the vapouriser's not hot enough).
If it was mine, first things I'd do:-
Save a copy of the config
Check the diagnosis page for anything obvious (it just shows if the injectors are running OK)
Update the firmware to the latest version (for the Romano it's 33.0)
Perform an auto-calibration
Save another copy of the config
The last two steps this weekend solved a "tripping over to petrol under high load and high RPM" issue that's always been there, and the car feels a bit nippier too.
Mine was fitted by Phil Price, he does autogas conversions and runs a rally school where all the cars are gassed. Gave me his old programming lead too - top bloke! Don't know how much he'd charge to inspect/repair/replace your system, but like I said if it's a Romano Sequential Vapour Injection system I've got the lead and can lend it to you - just add car and laptop with a serial port! Worth checking out before shelling out. You can also check the gas and reducer (vapouriser) temperatures using the software, this could highlight issues such as an airlock in the car's cooling system (although if this is the case a Romano system will probably stay in petrol mode as it'll know that the vapouriser's not hot enough).
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