2000 ls400 problem solving
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Driver School Candidate
Joined: Dec 2022
Posts: 18
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From: Oklahoma
2000 ls400 problem solving
been having trouble with my 2000 Lexus Ls400 with rough idle, acceleration problems (especially when the A/C is on) jerking in idle and when going in reverse. 1200+ rpm once started. I changed the spark plug in cylinder 4 which made the 304 go to the bottom of the codes listed. Just trying to figure out where I should start
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Joined: Jul 2019
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From: CA
This is where I would start. I'd do a compression test on the engine, all 8 cylinders to make sure you have reasonable compression throughout the engine to make sure you a reasonable good compression, then also I would clear all the codes, then check for trouble codes again. I wouldn't throw a ton of money at an engine that may or may not have a fundemental problem, you won't know until you perform a compression test.
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Joined: Jul 2019
Posts: 503
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From: CA
Make sure your timing belt looks okay, I mean if its never been replaced that's a big problem too. So that's where'd I'd start, the most important things, is my engine okay or is there something wrong with it. Because at that point if the engine is bad and you like the car, look at getting a known good engine and just replace it.
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 18
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From: Oklahoma
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 18
Likes: 1
From: Oklahoma
Make sure your timing belt looks okay, I mean if its never been replaced that's a big problem too. So that's where'd I'd start, the most important things, is my engine okay or is there something wrong with it. Because at that point if the engine is bad and you like the car, look at getting a known good engine and just replace it.
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 18
Likes: 1
From: Oklahoma
This is where I would start. I'd do a compression test on the engine, all 8 cylinders to make sure you have reasonable compression throughout the engine to make sure you a reasonable good compression, then also I would clear all the codes, then check for trouble codes again. I wouldn't throw a ton of money at an engine that may or may not have a fundemental problem, you won't know until you perform a compression test.
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Driver
Joined: Apr 2023
Posts: 86
Likes: 30
From: California
I'm sorry if I'm wrong, but I think that you've mistaken the accessory belt for the timing belt. Please read through the FAQ
https://www.clublexus.com/forums/ls-...questions.html
and especially the section on Timing Belt removal and installation. There is a tutorial with pictures that will give you an idea as to what parts are what...
https://www.clublexus.com/forums/ls-...questions.html
and especially the section on Timing Belt removal and installation. There is a tutorial with pictures that will give you an idea as to what parts are what...
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Racer
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From: Chandler, AZ
With that mileage, I would take the intake off and clean every passage going into the throttle body. There is an air mix path passage, accessible by removing a cover plate directly on top of the throttle body that gets gunked up with carbon. This is also responsible to how smoothly the transmission shifts and made a difference on my 162k mile car. Should be 8 little holes once the cover plate is removed, make sure they're not plugged.
Racer
Joined: Mar 2018
Posts: 1,906
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From: Nevada
You need to make sure the two large holes are also clean as well.
https://www.clublexus.com/forums/ls-...ttle-body.html
https://www.clublexus.com/forums/ls-...ttle-body.html
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 18
Likes: 1
From: Oklahoma
I'm sorry if I'm wrong, but I think that you've mistaken the accessory belt for the timing belt. Please read through the FAQ
https://www.clublexus.com/forums/ls-...questions.html
and especially the section on Timing Belt removal and installation. There is a tutorial with pictures that will give you an idea as to what parts are what...
https://www.clublexus.com/forums/ls-...questions.html
and especially the section on Timing Belt removal and installation. There is a tutorial with pictures that will give you an idea as to what parts are what...
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 18
Likes: 1
From: Oklahoma
With that mileage, I would take the intake off and clean every passage going into the throttle body. There is an air mix path passage, accessible by removing a cover plate directly on top of the throttle body that gets gunked up with carbon. This is also responsible to how smoothly the transmission shifts and made a difference on my 162k mile car. Should be 8 little holes once the cover plate is removed, make sure they're not plugged.
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 18
Likes: 1
From: Oklahoma
Instructor
Joined: Nov 2007
Posts: 1,107
Likes: 282
From: CA
If the VSC light is on, this is where I would start. Your report doesn't show any VSC codes, probably because Autozone's scan tool doesn't read manufacturer specific codes. You'll need to pull the codes thru the underhood DTC1 connector (located on the driver's side of the intake manifold).
Last edited by paulo57509; Aug 15, 2023 at 03:42 PM.
Driver
Joined: Apr 2023
Posts: 86
Likes: 30
From: California
Sounds horrible. I would take off the accessory belt and try and spin the idler pulley and tensioner pulleys by hand. I'm hoping that it's those bearings that are bad and not the idler and tensioner bearings inside the timing belt covers that are making that noise. I guess it also could be the bearing on the fan bracket or even the water pump. Try and find out what is making the loud sound. Harbor Freight has mechanic's stethoscopes for a reasonable price...
And did you see a sticker on any of the engine covers that noted the date and mileage that the timing belt was changed? That is of the utmost importance with the '98-00 ls400's as our engines are interference engines, which means that the pistons and valves can damage each other if the timing belt breaks which basically means writing off the engine and either replacing it, or junking the car. Bad place to be and expensive either way.
And did you see a sticker on any of the engine covers that noted the date and mileage that the timing belt was changed? That is of the utmost importance with the '98-00 ls400's as our engines are interference engines, which means that the pistons and valves can damage each other if the timing belt breaks which basically means writing off the engine and either replacing it, or junking the car. Bad place to be and expensive either way.