Hey all, I am currently trying to bring my 90 ls back up to perfect working condition (or as close as I can get) and was just wondering if any of you can reply to any issues you’ve had and the fixes/troubleshooting you went through to resolve the issue. I’ve got a few ongoing that it’s taken two shops and a few senior techs to look at. So for documentation for everyone’s sake I thought it would be helpful to get previous issues that have been dealt with, but or small, and their fixes documented it would help everyone out! So please if you’ve got a first gen with some odd issues and that you’ve gotten to the bottom of I’d love to hear it.

 

By far, the ECU is one of the most overlooked issues. Especially if a tech is not familiar with the LS.

 

Yeah that’s going to be my next move after reading the sticky post on ECU repair, I don’t have most of the issues that were listed but there are some that se on there.

 

I grabbed a video of one of the issues I’m having (I can’t seem to upload it now), hoping to catch it stalling which it’s done a few times now but the tachometer dances around when idling and then when I press on the brake it causes it to drop. So I’m thinking brake booster leak or vacuum leak? Because if it’s a vacuum leak it may explain why I’m having a starting issue with the fuel pressure dropping once the car is turned off and left to sit for a few minutes.

 

Check the vacuum line going to the back of the intake manifold from the brake booster. All the vacuum hosing is shot from age if its original so you might as well replace it all.

 

To continue this thread. I have another issue that’s been ongoing, I found out that the pervious owner did an idle up delete and I’m not wondering if that’s the cause of the hissing that comes only when pulling away, if I keep it at low rpm I can get the sound to continue on but after it’s gone it doesn’t come back until the engine starts again.

I’ll link the video herehttps://youtube.com/shorts/-lNnuvWt7HI?feature=share

 

When i got mine the owner had done the idle up delete as well. However it did not make the noise you are experiencing. Again, I would check all vacuum lines/connections in the engine bay.

 

Hi - I have a '98 LS with 166K miles and the brake pedal is very hard to press with intermittent hissing sound and needs a lot of brake pedal pressure to stop. All signs indicate it's probably the brake booster. The booster and master are all original. Before I replace the booster I wanted to make sure it is not the other parts that is attached to it. I have a couple of questions if anyone can help: (1) the vacuum hose from the manifold (union) to the check valve is very hard and looks brittle so I figure I'll start with this since it will likely need to be replaced if I replace the booster. However I cannot find the part (44773F / 44773-50020) anywhere, not even a replacement except from lexuspartsnow.com but I've seen some very negative feedback about this vendor posted in our forum... Anyone knows where I can purchase one? (2) I saw a thread with someone saying about a hissing sound coming from their booster although the thread did not mention whether the pedal was hard or any diminished braking. The Thread Starter said he was able to solve the problem by replacing the gasket between the master and the booster; the gasket part is 47275-12020. Does any know if this gasket is bad whether it would cause the hard brake pedal and diminished braking? Thanks in advance!

 

The only problem I ever had is they mixed up 00100 with 00010 (or something like that) on the part number and sent me the air filter for a 2000-something ES instead of my LS. They fixed it right away. I've used lexuspartsnow for probably about 8 orders on my car and otherwise have never had an issue personally. But I understand I'm a sample size of one.

 

IIRC, the hose doesn't have tight bends in it. You can probably get away with bulk hose. If you go this route, be sure to get hose specifically for power brakes (not PCV, fuel, etc.). Brake hose is constructed to be able to withstand vacuum levels that the booster requires. You don't want hose that will collapse.

https://www.gates.com/us/en/fluid-po...00-000000.html

 

My advice is to buy the best parts you can afford when you do replace things My mistake over multiple LS400s has been using the cheapest rock auto parts and it truly degrades the car.

 

My 90ls400 had really bad spongy brakes when i got it and payed a mechanic a few hundred to fix them, they went spongy again and i remember it sounded like air escaping and they wouldn’t stop the car until the pedal was at the very bottom so i pulled a wheel off and saw a bad brake line that was pulling air into the system i probably just got lucky but i would start with the little things

 

Agreed, it does not matter if it's an "old car". I have "saved" money on inferior aftermarket parts only to be eventually replaced with OEM. OEM will last way longer and the LS will reward you with its refinement and reliability in return.

I recommend finding a dealer that has an online parts store and working with them. Overseas suppliers Amayama/Partsouq are also great for the expensive bits ie: shift solenoids. You will wait twice as long to receive the parts in exchange for a cheaper price.

 

I've gone aftermarket for two items before I knew better. Beck/Arnley sway bar endlinks which, so far, have been perfectly fine.

Other other were shock mounts, KYB. Failed in 10,000 miles 🙃

 

There are always some exceptions, no doubt.
I do have Moog sway bar links in the front and back which were ironically made in Japan, so far so good. Its hard to justify spending $75-$85 a link when you can spend $20 and they will most likely last a while.