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hi all been puzzling over the high idling for some time and think have the solution but just run it passed you 1st. reason for idle high is the pipe that is meant to run from before the air flow meter to the idle speed control ISC in normal LS400, in the old LPG conversion this pipe has to be put after the air flow meter so the air flow meter reads a flow of air and the ECU chucks in more fuel and idles high . i did try and solve this by altering the throttle position sensor as slack as it could go on the screw holes and have it to 1000rpm when at temp and 1400rpm when cold but i think there is still too much air going in and hence more fuel. so solution i have come up with is the following
sorry hand drawn ha!
because the lpg gets fed into the inlet manifold the feed is tapped in on the throttle body and then a pipe comes out the throttle body and to the ISC so when on petrol or LPG at idle and the butterfly is shut air goes passed the air flow meter and causes it to idle high so as the diagram shows i will have a 12v solenoid valve on the ISC pipe before the flow meter for petrol and on the pipe after the air flow meter for the LPG ( the LPG has to go after the AFM as not to blow it or damage AFM)
the wiring side is fairly straight forward i will have a 5 pin relay and feed the petrol valve on ST2 and IG2 on the ignition so it is open when start the car and the LPG is off and when flick over to LPG flick the switch to close the petrol valve and open the LPG, i will see if i can wire it to the LPG switch so its only one switch and instant.
any comments??
sorry hand drawn ha!
because the lpg gets fed into the inlet manifold the feed is tapped in on the throttle body and then a pipe comes out the throttle body and to the ISC so when on petrol or LPG at idle and the butterfly is shut air goes passed the air flow meter and causes it to idle high so as the diagram shows i will have a 12v solenoid valve on the ISC pipe before the flow meter for petrol and on the pipe after the air flow meter for the LPG ( the LPG has to go after the AFM as not to blow it or damage AFM)
the wiring side is fairly straight forward i will have a 5 pin relay and feed the petrol valve on ST2 and IG2 on the ignition so it is open when start the car and the LPG is off and when flick over to LPG flick the switch to close the petrol valve and open the LPG, i will see if i can wire it to the LPG switch so its only one switch and instant.
any comments??