LPG and ISC

hi all, about a year ago did the 1UZFE engine swap into a LN130 and then got it LPGed, what the guy did was to fix a valve to on the pipe from the main air inlet to the ISC and have it virtully closed so when starting from cold you needed to put your foot on the accelarator peddle and then when at temp it would idle about 800 if you have the valve fully open it starts and no need to press the accelarator but idles at 1800 at temp.

the mpg is really low about 12mpg on gas and 14 petrol so i was going through the lexus FSM trouble shooting page and am going to change the temp sensor and look at the throttle postion sensor but it does list the ISC as a potential problem which it seems to be at the moment

any thoughts?
 

zen

New Member
hi all, about a year ago did the 1UZFE engine swap into a LN130 and then got it LPGed, what the guy did was to fix a valve to on the pipe from the main air inlet to the ISC and have it virtully closed so when starting from cold you needed to put your foot on the accelarator peddle and then when at temp it would idle about 800 if you have the valve fully open it starts and no need to press the accelarator but idles at 1800 at temp.


the mpg is really low about 12mpg on gas and 14 petrol so i was going through the lexus FSM trouble shooting page and am going to change the temp sensor and look at the throttle postion sensor but it does list the ISC as a potential problem which it seems to be at the moment




any thoughts?

its a v8 4l...i get 15 on gas...wont get much any better..mines manual too..mines sequential injection..yours sounds single point..
and a picture of what done..
 
it is single point, the old version of LPG as it feeds into the air inlet / throttle body. the problem is the pipe that goes from the air inlet before the air flow sensor to the ISC has gone and the way the PLG is set up this pipe is after the air flow sensor as when the throttle is shut the engine couldnt tick over so itl feeds in through the ISC. this being, air is going passed the air flow sensor when throttle is closed when it shouldnt be and pushing up the revs. i have combated this by altering the position of the throttle sensor to its lowest possible position and now it idles at 1400 when cold and 1000 when warm.
 
with a single point mixer run a manifold vac (charcoal canister line) hose to a small needle valve and then to the low pressure gas side of the converter or mixer, this will allow you to set the idle mixtures much better and run a lean cruise metering rod in impco mixers.
 
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