FYI I have a 2001 hilux 4WD 3RZ-FE with same problem. Vehicle been running on LPG for 60K with no problems except valve recesion of 6thou every 10k. Rebuilt cyl head 5k ago. This is normal as the intake seats and valves are of poor quality. No problem just need to be able to grind your own shims to be cost effective. Vehicle pulls much better on LPG rather than ULP. This should not be the case as there is more energy in ULP per intake stroke. I have put in a Jaycar air fuel mixture kit mainly for tuning the LPG as my system has mods and the factory system is open loop so no reporting back to ECU regarding exhaust conditions as factory system does not have any oxcygen sensors fitted. Vehicle runs very lean on ULP regadless of throtle position. No problem with the Mass Air Flow meter, which is also combines the air intake temp sensor. this tests OK. No fault codes displayed when pins 4 and 13 on the DLC3 are shorted (once ECU has been reset with removal of EFI fuse or battery isolation and vehicle driven through usual driving cycles). I will check again the Throtle Position Sensor output as I don't have the option of part swaping. Must admit that this is frustrating so any feed back welcome. Vehicle runs very well on LPG so problem is not related to timing / spark etc. Currently playing with the factory variable resistor settings which is wired in with the TPS sensor. Have checked variable resistor and all seems to test ok. I agree with past comments that the power when running ULP seemed to be like hiting band in a two stroke. This used to occure once you got up to 3500rpm. I have tried OBD scan tools but system is M-OBD so no go. Short out pins 4 and 13 does the job. Can email cheat sheet if interested. Any ideas? Just joined up so still working out how to change my profile, system won't let me , must be doing something wrong. Cheers Bloke
