ok so i got the car cheap i mean real cheap like ten dollars cheap 1990 ls 400.You people would not belive the story but short, saw a guy kickin the car, he thaught it seized but was a battery lmao "he really didnt want the car" Been running for three years now and still no sounds of engine fade at all, i changed out the air intake and made a short ram induction,wow what a diffrence, lately since the summer was so hot i ran it every day with the a/c on and had no problem, now its getting cold, turned the a/c off and now the idle runs about 200 rpm barely even on. The engine will shut off and will stay at low rpm untill i put the a/c back on but even then still has a problem idleing untill i guess it registers, then after like 10 mins it goes back up to 700-850 rpm, no problems at all, does'nt shut off when comming to stops or anything, im stumped im pretty good at cars but have;nt a clue, any ideas?

 

temp sensor. about to change mine along with o2 sensor since im getting the codes for it. temp sensor will not send codes. im in florida so i wont notice the cold thing as much. until maybe january. bu mine wont get upto temp when i shut my air off. 22 bucks autozone or 68 at lexus or toyota. still havent seen any proof the oem is worth the extra 40+ dollars.

search temp sensor and do it.

 

cheaper fix, just idle it up,

 

i did the cheaper fix but after a week or two the idle will go up to 1200-1400 rpm

 

so it'd go from 200 to 1200? i'd check the idle air system. start out cheapest first just clean the butterfly in the throttle body/upper intake

 

the temp goes up no prblem either, right in the middle, did the infrored temp thing and read 180 degrees

 

if i have the a/c on and adjust the idle at 800 rpm it will be good untill i turn the a/c off

 

there is three temp sensors actualy 4 but ill tell you about three. one in the radiator for the fans. then two right next to each other left hand side front of the block. one for the temp gauge and one that sends the temp to the ECU/ECM. this one that sends to the ECM/ECU is the important one that kills gass milage and will make the car run weird.

the green one in this picture. found here. >>> https://www.clublexus.com/forums/ls4...ange-pics.html

 

to skulcracka, is that gona be the cheapest fix for now insted of a TPS?

 

yes and your tps is probly fine unless you messed with it but easy to reset the TPS.

get engine warm/upto temp then do that in that link.

http://www.lexls.com/tutorials/EFI/tps.html

 

not the tps it self but the adjustment screw underneath with the lock nut.

 

had mine like 3 weeks so cant speak of that screw. i have a 93.

isnt that the throttle cable ajuster??? or for the throttle body itself?

 

behind the adjustment screw is a plunger lookin sensor that moves in and out as the idle raises and lowers

 

if you messed with that dont know what to tell you maybe someone else will.