Low idle issue solved
Thread Starter
Driver School Candidate
Joined: Mar 2021
Posts: 8
Likes: 2
From: Washington
Low idle issue solved
I wanted to post this thread as I’ve been following the board for a few years and have only gotten small clues on this problem, I see countless posts of the same issue but never a final post that it’s been solved. And loads of Lexus owners racing to change out part after part in hopes it will help. Or looking into replacing the ecu one two or three times!
a brief history, I bought my 90 ls400 1uzfe from a friend that builds drift cars, he could no longer have 3 cars in his apartment so I got it for literally a steal! 300$
the car ran great! Had a small power steering leak. I didn’t think anything of it at the time. Just made sure to top it off every few weeks to a month when I could feel the steering getting tight.
I did always wondered why it acted like an old hotrod like my 78 Chevy 327 small block, as in it would idle high at start then drop down once the “choke” disengaged. In the case of the Lexus I now understand this is just open and closed loop.
I did not like that it would drop in idle cause I just love to use the road as my racetrack and more power “higher idle” is a go to for me! a normal Lexus will drop in idle but as I now “7 years later” have come to find mine was dropping too low, when I first got it, the issue was almost not an issue and in-knowticable. As the years went on the idle at operational temp got lower and lower down to 200rpm. This never affected the power of the car and she passed the wide open test without flaw never coughed or chocked when flooring in idle or drive,
My dumb *** neglected to fix power steering pump. And I ran the car for 3 years without any power steering, I of course kept it full of fluid, but just accepted the daily arm workout to drive.
in the last 2 years the air valve completely failed and started sucking in power steering fluid into the intake. I found out as many others to remove this idle air valve for the pump and plug the hole and cap the air lines on the intake,
finally this year the idle got so bad that I could not sit in traffic or she would die, so I changed out the pump “hoping this was the cause” and got a new power steering idle air valve, I figured why not put the correct setup back together,
to my dismay this only solved the steering issue, the idle was still horrible, “only once it reached operational temp”
then I, changed the roaters, caps, distributors, sparks, wires, and all vacuum lines. Still great startup but once she got warm idle dropped to 200rpm sad 😞
checked the fuel pressure, vacuum pressure, checked the fuel pump itself, checked the ecu, ignition, ignition modules, ignition coils, maf, etc sensor, tps, fuel injectors. IACV EVERYTHING! replaced some and checked others for proper operation in Different weather condition,
ran down all wires and relays, fuses, connections everything was just fine and dandy, except for my idle. A year into tearing apart and rebuilding this thing more times than I can count I was at my wits end,
took it to 5 shops here in Washington, all refused to even attempt diagnose the issue for under 500$ with no guarantee they could find anything, what a joke, called 3 Lexus mechanics and same thing just more expensive. Pathetic.
in conclusion as this is now a long thread. The idle problem was solved by looping the power steering idle valve to itself, others can just plug this hole up, “I recommend removing the valve, breaking the plastic off, welding, or jb-welding the hole shut and using the same part to plug up the pump”, don’t go trying to find a bolt to fit when you have one already that you know is the right fit.
Now that this is looped to itself take the hose from the air intake “just after the maf” and loop it to the nipple on the intake manifold. This will supply the engine with just a little bit of direct air, the air is already measured cause it passed the maf so your not really messing with mixtures.
BOOM! My Lexus now idles at 600+- 50 in idle and in drive. I really hope this post helps out some as my battle with this was not only infuriating because the engine runs great just not at idle, but might help some out with not replacing parts that Lexus has made to last a good long while. Lexus did an amazing job with this engine “not the power steering idle valve”
hence why nobody has cracked the ecu yet but everyone wants to build these cars. I could go on forever in this post and left many things out so feel free to ask any questions if your are in the same boat I was in. Cheeres fellas. And thanks a lot for all the help I could not have done all this without the forums and the GOD who created this site and the original sister site.
a brief history, I bought my 90 ls400 1uzfe from a friend that builds drift cars, he could no longer have 3 cars in his apartment so I got it for literally a steal! 300$
the car ran great! Had a small power steering leak. I didn’t think anything of it at the time. Just made sure to top it off every few weeks to a month when I could feel the steering getting tight.
I did always wondered why it acted like an old hotrod like my 78 Chevy 327 small block, as in it would idle high at start then drop down once the “choke” disengaged. In the case of the Lexus I now understand this is just open and closed loop.
I did not like that it would drop in idle cause I just love to use the road as my racetrack and more power “higher idle” is a go to for me! a normal Lexus will drop in idle but as I now “7 years later” have come to find mine was dropping too low, when I first got it, the issue was almost not an issue and in-knowticable. As the years went on the idle at operational temp got lower and lower down to 200rpm. This never affected the power of the car and she passed the wide open test without flaw never coughed or chocked when flooring in idle or drive,
My dumb *** neglected to fix power steering pump. And I ran the car for 3 years without any power steering, I of course kept it full of fluid, but just accepted the daily arm workout to drive.
in the last 2 years the air valve completely failed and started sucking in power steering fluid into the intake. I found out as many others to remove this idle air valve for the pump and plug the hole and cap the air lines on the intake,
finally this year the idle got so bad that I could not sit in traffic or she would die, so I changed out the pump “hoping this was the cause” and got a new power steering idle air valve, I figured why not put the correct setup back together,
to my dismay this only solved the steering issue, the idle was still horrible, “only once it reached operational temp”
then I, changed the roaters, caps, distributors, sparks, wires, and all vacuum lines. Still great startup but once she got warm idle dropped to 200rpm sad 😞
checked the fuel pressure, vacuum pressure, checked the fuel pump itself, checked the ecu, ignition, ignition modules, ignition coils, maf, etc sensor, tps, fuel injectors. IACV EVERYTHING! replaced some and checked others for proper operation in Different weather condition,
ran down all wires and relays, fuses, connections everything was just fine and dandy, except for my idle. A year into tearing apart and rebuilding this thing more times than I can count I was at my wits end,
took it to 5 shops here in Washington, all refused to even attempt diagnose the issue for under 500$ with no guarantee they could find anything, what a joke, called 3 Lexus mechanics and same thing just more expensive. Pathetic.
in conclusion as this is now a long thread. The idle problem was solved by looping the power steering idle valve to itself, others can just plug this hole up, “I recommend removing the valve, breaking the plastic off, welding, or jb-welding the hole shut and using the same part to plug up the pump”, don’t go trying to find a bolt to fit when you have one already that you know is the right fit.
Now that this is looped to itself take the hose from the air intake “just after the maf” and loop it to the nipple on the intake manifold. This will supply the engine with just a little bit of direct air, the air is already measured cause it passed the maf so your not really messing with mixtures.
BOOM! My Lexus now idles at 600+- 50 in idle and in drive. I really hope this post helps out some as my battle with this was not only infuriating because the engine runs great just not at idle, but might help some out with not replacing parts that Lexus has made to last a good long while. Lexus did an amazing job with this engine “not the power steering idle valve”
hence why nobody has cracked the ecu yet but everyone wants to build these cars. I could go on forever in this post and left many things out so feel free to ask any questions if your are in the same boat I was in. Cheeres fellas. And thanks a lot for all the help I could not have done all this without the forums and the GOD who created this site and the original sister site.
Pole Position
Joined: Nov 2014
Posts: 3,254
Likes: 418
From: CALIFORNIA
I wanted to post this thread as I’ve been following the board for a few years and have only gotten small clues on this problem, I see countless posts of the same issue but never a final post that it’s been solved. And loads of Lexus owners racing to change out part after part in hopes it will help. Or looking into replacing the ecu one two or three times!
a brief history, I bought my 90 ls400 1uzfe from a friend that builds drift cars, he could no longer have 3 cars in his apartment so I got it for literally a steal! 300$
the car ran great! Had a small power steering leak. I didn’t think anything of it at the time. Just made sure to top it off every few weeks to a month when I could feel the steering getting tight.
I did always wondered why it acted like an old hotrod like my 78 Chevy 327 small block, as in it would idle high at start then drop down once the “choke” disengaged. In the case of the Lexus I now understand this is just open and closed loop.
I did not like that it would drop in idle cause I just love to use the road as my racetrack and more power “higher idle” is a go to for me! a normal Lexus will drop in idle but as I now “7 years later” have come to find mine was dropping too low, when I first got it, the issue was almost not an issue and in-knowticable. As the years went on the idle at operational temp got lower and lower down to 200rpm. This never affected the power of the car and she passed the wide open test without flaw never coughed or chocked when flooring in idle or drive,
My dumb *** neglected to fix power steering pump. And I ran the car for 3 years without any power steering, I of course kept it full of fluid, but just accepted the daily arm workout to drive.
in the last 2 years the air valve completely failed and started sucking in power steering fluid into the intake. I found out as many others to remove this idle air valve for the pump and plug the hole and cap the air lines on the intake,
finally this year the idle got so bad that I could not sit in traffic or she would die, so I changed out the pump “hoping this was the cause” and got a new power steering idle air valve, I figured why not put the correct setup back together,
to my dismay this only solved the steering issue, the idle was still horrible, “only once it reached operational temp”
then I, changed the roaters, caps, distributors, sparks, wires, and all vacuum lines. Still great startup but once she got warm idle dropped to 200rpm sad 😞
checked the fuel pressure, vacuum pressure, checked the fuel pump itself, checked the ecu, ignition, ignition modules, ignition coils, maf, etc sensor, tps, fuel injectors. IACV EVERYTHING! replaced some and checked others for proper operation in Different weather condition,
ran down all wires and relays, fuses, connections everything was just fine and dandy, except for my idle. A year into tearing apart and rebuilding this thing more times than I can count I was at my wits end,
took it to 5 shops here in Washington, all refused to even attempt diagnose the issue for under 500$ with no guarantee they could find anything, what a joke, called 3 Lexus mechanics and same thing just more expensive. Pathetic.
in conclusion as this is now a long thread. The idle problem was solved by looping the power steering idle valve to itself, others can just plug this hole up, “I recommend removing the valve, breaking the plastic off, welding, or jb-welding the hole shut and using the same part to plug up the pump”, don’t go trying to find a bolt to fit when you have one already that you know is the right fit.
Now that this is looped to itself take the hose from the air intake “just after the maf” and loop it to the nipple on the intake manifold. This will supply the engine with just a little bit of direct air, the air is already measured cause it passed the maf so your not really messing with mixtures.
BOOM! My Lexus now idles at 600+- 50 in idle and in drive. I really hope this post helps out some as my battle with this was not only infuriating because the engine runs great just not at idle, but might help some out with not replacing parts that Lexus has made to last a good long while. Lexus did an amazing job with this engine “not the power steering idle valve”
hence why nobody has cracked the ecu yet but everyone wants to build these cars. I could go on forever in this post and left many things out so feel free to ask any questions if your are in the same boat I was in. Cheeres fellas. And thanks a lot for all the help I could not have done all this without the forums and the GOD who created this site and the original sister site.
a brief history, I bought my 90 ls400 1uzfe from a friend that builds drift cars, he could no longer have 3 cars in his apartment so I got it for literally a steal! 300$
the car ran great! Had a small power steering leak. I didn’t think anything of it at the time. Just made sure to top it off every few weeks to a month when I could feel the steering getting tight.
I did always wondered why it acted like an old hotrod like my 78 Chevy 327 small block, as in it would idle high at start then drop down once the “choke” disengaged. In the case of the Lexus I now understand this is just open and closed loop.
I did not like that it would drop in idle cause I just love to use the road as my racetrack and more power “higher idle” is a go to for me! a normal Lexus will drop in idle but as I now “7 years later” have come to find mine was dropping too low, when I first got it, the issue was almost not an issue and in-knowticable. As the years went on the idle at operational temp got lower and lower down to 200rpm. This never affected the power of the car and she passed the wide open test without flaw never coughed or chocked when flooring in idle or drive,
My dumb *** neglected to fix power steering pump. And I ran the car for 3 years without any power steering, I of course kept it full of fluid, but just accepted the daily arm workout to drive.
in the last 2 years the air valve completely failed and started sucking in power steering fluid into the intake. I found out as many others to remove this idle air valve for the pump and plug the hole and cap the air lines on the intake,
finally this year the idle got so bad that I could not sit in traffic or she would die, so I changed out the pump “hoping this was the cause” and got a new power steering idle air valve, I figured why not put the correct setup back together,
to my dismay this only solved the steering issue, the idle was still horrible, “only once it reached operational temp”
then I, changed the roaters, caps, distributors, sparks, wires, and all vacuum lines. Still great startup but once she got warm idle dropped to 200rpm sad 😞
checked the fuel pressure, vacuum pressure, checked the fuel pump itself, checked the ecu, ignition, ignition modules, ignition coils, maf, etc sensor, tps, fuel injectors. IACV EVERYTHING! replaced some and checked others for proper operation in Different weather condition,
ran down all wires and relays, fuses, connections everything was just fine and dandy, except for my idle. A year into tearing apart and rebuilding this thing more times than I can count I was at my wits end,
took it to 5 shops here in Washington, all refused to even attempt diagnose the issue for under 500$ with no guarantee they could find anything, what a joke, called 3 Lexus mechanics and same thing just more expensive. Pathetic.
in conclusion as this is now a long thread. The idle problem was solved by looping the power steering idle valve to itself, others can just plug this hole up, “I recommend removing the valve, breaking the plastic off, welding, or jb-welding the hole shut and using the same part to plug up the pump”, don’t go trying to find a bolt to fit when you have one already that you know is the right fit.
Now that this is looped to itself take the hose from the air intake “just after the maf” and loop it to the nipple on the intake manifold. This will supply the engine with just a little bit of direct air, the air is already measured cause it passed the maf so your not really messing with mixtures.
BOOM! My Lexus now idles at 600+- 50 in idle and in drive. I really hope this post helps out some as my battle with this was not only infuriating because the engine runs great just not at idle, but might help some out with not replacing parts that Lexus has made to last a good long while. Lexus did an amazing job with this engine “not the power steering idle valve”
hence why nobody has cracked the ecu yet but everyone wants to build these cars. I could go on forever in this post and left many things out so feel free to ask any questions if your are in the same boat I was in. Cheeres fellas. And thanks a lot for all the help I could not have done all this without the forums and the GOD who created this site and the original sister site.
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