1998 Ls400 Low Idle Dies When Warm Except W Ac On
#16
1998 LS400 110k mi.
Starts and runs fine when cold.
Once warm, idles too low, 300-400 RPM, and will die unless either I give it some gas or turn the AC on. No CEL.
Can someone give me some ideas. When I search for my symptoms, I'm just seeing solutions for 1st gen LS400 with the IACV problem. I don't see an IACV on this motor. I've got the TB off now for cleaning. Anything else I should do to adress this problem while the TB is off?
Anyone have this issue on a 98+ vvti 1uzfe or 2uzfe?
Thanks!
Starts and runs fine when cold.
Once warm, idles too low, 300-400 RPM, and will die unless either I give it some gas or turn the AC on. No CEL.
Can someone give me some ideas. When I search for my symptoms, I'm just seeing solutions for 1st gen LS400 with the IACV problem. I don't see an IACV on this motor. I've got the TB off now for cleaning. Anything else I should do to adress this problem while the TB is off?
Anyone have this issue on a 98+ vvti 1uzfe or 2uzfe?
Thanks!
I try to find the idle control valve. I can't located.
#18
1998 LS400 110k mi.
Starts and runs fine when cold.
Once warm, idles too low, 300-400 RPM, and will die unless either I give it some gas or turn the AC on. No CEL.
Can someone give me some ideas. When I search for my symptoms, I'm just seeing solutions for 1st gen LS400 with the IACV problem. I don't see an IACV on this motor. I've got the TB off now for cleaning. Anything else I should do to adress this problem while the TB is off?
Anyone have this issue on a 98+ vvti 1uzfe or 2uzfe?
Thanks!
Starts and runs fine when cold.
Once warm, idles too low, 300-400 RPM, and will die unless either I give it some gas or turn the AC on. No CEL.
Can someone give me some ideas. When I search for my symptoms, I'm just seeing solutions for 1st gen LS400 with the IACV problem. I don't see an IACV on this motor. I've got the TB off now for cleaning. Anything else I should do to adress this problem while the TB is off?
Anyone have this issue on a 98+ vvti 1uzfe or 2uzfe?
Thanks!
#21
hey all.. i have a similar problem, except my car dies when there is a load on it.. as in turning the ac on while idling or in stop and go traffic will likely kill my battery
i have replaced both the battery and my alternator.. here's my problem.. normally when you turn the ac on or put a load on the car, the rpm's go higher to compensate.. instead in my car, the rpm's drop even more.. so it idles realllly low with the load on the battery, it idles even lower with the radio AND the ac on.. pretty much kills my battery in city driving.. on the highway it's fine cause of the high rpm's
i'm hearing a lot about the throttle body and the tps.. are these symptoms related to those two things?
thanks in advance
i have replaced both the battery and my alternator.. here's my problem.. normally when you turn the ac on or put a load on the car, the rpm's go higher to compensate.. instead in my car, the rpm's drop even more.. so it idles realllly low with the load on the battery, it idles even lower with the radio AND the ac on.. pretty much kills my battery in city driving.. on the highway it's fine cause of the high rpm's
i'm hearing a lot about the throttle body and the tps.. are these symptoms related to those two things?
thanks in advance
#23
i just bought a 99 ls400 with 95k miles on it. warm Idle in D no headlights no AC, tach reads 200 rpm with accompanying harsh vibration coming from engine compartment that smoothes out in N at higher rpm 600~. As long as i run it like this in the past week it has not stalled.
I took it to the shop and they said the scanner was reading 500~600 rpm and that my tach is bad. BUUUT the tach behaves properly under all situations and moves the right way when it the shifts or i go into N or R, whatever. But usually when i start the car cold it doesn't move and then i have to whack the dash, which immediately brings it to life.
the car also has reasonable torque when i take my foot off the brake at idle, but not quite the torque of an engine running at 600 rpm. the mechanic suggested it was just the motor mounts causing the problem but i wouldn't expect them to be that bad at this mileage.
so to summarize.
reasons why i think its the engine causing the prob: don't think MM's could go this bad at this mileage, don't think the tach is broken.
reasons why the mechanic is right: the scanner said so, the car actually moves when i take my foot off the brake and i want him to be.
Also this is a florida car that spent the last 4 years in new york perhaps ECU caps are the culprit in the humid florida climate
I took it to the shop and they said the scanner was reading 500~600 rpm and that my tach is bad. BUUUT the tach behaves properly under all situations and moves the right way when it the shifts or i go into N or R, whatever. But usually when i start the car cold it doesn't move and then i have to whack the dash, which immediately brings it to life.
the car also has reasonable torque when i take my foot off the brake at idle, but not quite the torque of an engine running at 600 rpm. the mechanic suggested it was just the motor mounts causing the problem but i wouldn't expect them to be that bad at this mileage.
so to summarize.
reasons why i think its the engine causing the prob: don't think MM's could go this bad at this mileage, don't think the tach is broken.
reasons why the mechanic is right: the scanner said so, the car actually moves when i take my foot off the brake and i want him to be.
Also this is a florida car that spent the last 4 years in new york perhaps ECU caps are the culprit in the humid florida climate
#24
i just bought a 99 ls400 with 95k miles on it. warm Idle in D no headlights no AC, tach reads 200 rpm with accompanying harsh vibration coming from engine compartment that smoothes out in N at higher rpm 600~. As long as i run it like this in the past week it has not stalled.
I took it to the shop and they said the scanner was reading 500~600 rpm and that my tach is bad. BUUUT the tach behaves properly under all situations and moves the right way when it the shifts or i go into N or R, whatever. But usually when i start the car cold it doesn't move and then i have to whack the dash, which immediately brings it to life.
the car also has reasonable torque when i take my foot off the brake at idle, but not quite the torque of an engine running at 600 rpm. the mechanic suggested it was just the motor mounts causing the problem but i wouldn't expect them to be that bad at this mileage.
so to summarize.
reasons why i think its the engine causing the prob: don't think MM's could go this bad at this mileage, don't think the tach is broken.
reasons why the mechanic is right: the scanner said so, the car actually moves when i take my foot off the brake and i want him to be.
Also this is a florida car that spent the last 4 years in new york perhaps ECU caps are the culprit in the humid florida climate
I took it to the shop and they said the scanner was reading 500~600 rpm and that my tach is bad. BUUUT the tach behaves properly under all situations and moves the right way when it the shifts or i go into N or R, whatever. But usually when i start the car cold it doesn't move and then i have to whack the dash, which immediately brings it to life.
the car also has reasonable torque when i take my foot off the brake at idle, but not quite the torque of an engine running at 600 rpm. the mechanic suggested it was just the motor mounts causing the problem but i wouldn't expect them to be that bad at this mileage.
so to summarize.
reasons why i think its the engine causing the prob: don't think MM's could go this bad at this mileage, don't think the tach is broken.
reasons why the mechanic is right: the scanner said so, the car actually moves when i take my foot off the brake and i want him to be.
Also this is a florida car that spent the last 4 years in new york perhaps ECU caps are the culprit in the humid florida climate
I experience this same issue to some degree. Not 200 rpms.. More like 450 with no Ac and no lights. My motor mounts are going bad and I'm @ 82k on a 2000.
#25
just cant believe an ls400 tachometer would be inaccurate, motor mounts ok but the tach??? perhaps an ecu caps thing. I would love for the esteemed lscowboyls or yamae to chime in on this one. i also have an intermittent check engine light that is apparently from a lean o2 sensor. maybe related?
#28
Motor mounts...
Any error codes? How's the fuel mileage? Many possibilities to randomly run off. Check the vacuum hoses, leaks there and especially to the intake plenum are critical.
Any error codes? How's the fuel mileage? Many possibilities to randomly run off. Check the vacuum hoses, leaks there and especially to the intake plenum are critical.
#29
Cleaning the MAF and running the Techron chevron gas cleaner is meant to stop the intermittent code from reappearing and most likely will not fix the underlying issue. It did however fix my SAME issue of idling low, running rich and car dying so give it a try. Make sure to use a MAF cleaner though.
#30
I also suggest you to clean the throttle body and the air mix path to injectors. For models 98-00, the ECU capacitors cause the AT shifting problems first in most of the cases. Your problem is not directly related to ECU capacitors, I assume. Of course it would be good to replace capacitors as a preventive measure like I did. But this will not be removing your problem, I can imagine.
Don't you notice any slow acceleration then an unexpected speed up when you turn a corner or slow down at a speed bump? A badly clogged throttle body confuses the ECU and causes this symptom when you speed down then accelerate. In other words, the symptom is described that the gas pedal does not respond as you expect once you speed down and then speed up.