1992 LS400 Fun Repair Times

[Spartan0536]

Hello everyone, it's been awhile, I have been working and dealing with life stuff and my gaming clan. My house is still not finished (stupid county paperwork, uggghh) but that is a different story.

For those of you that may not remember I have had some pretty weird issues since I bought my 1992 LS400 with 86,500 original miles (car was garage kept, full service history, all service plans and additional serves were done by my local Lexus dealer by the original owner until he passed away), so I do not have a junker LS400, it's quite a rare specimen.

That being said, LS400's especially 1990-1998 LS400's seem to have this nagging issue.... ECU failure. Yes those dreaded words that make people run for the hills and think about scrap heaping their cars due to a $1200 new part (IF YOU CAN GET ONE), plus labor, reprogramming at the dealer... just a ****ing nightmare.

So here is what was/is going on with my car...

1. poor acceleration compared to videos I have seen on the internet, just overall poor performance, and you can feel a difference intermittently where it has power. When I first test drove the car and I hit the gas pedal to the floor I threw me into my seat, over the next few months, it does not always do that, it feels sluggish.

2. My Climate Control randomly turns itself on and off, and I mean the entire system shuts off, no blowing air AT ALL. I have sent my climate control unit to Tanin Auto Electronix for repair and upgrade, they found nothing wrong with my climate control unit, but I had the LED's changed to a modern white (kept the OEM green indicator LED's), so at least I found out it was not the climate control unit and I got a nice looking custom part now.

3. My front cooling fans were not turning on at all, I replaced the sensor and now they are always on, and this sensor was not a reman, it's new, made sure the part numbers matched.

4. Remote door unlock not working

5. Smell of exhaust running rich

6. RPM (tachometer) reading 150 RPM when on low idle

7. Recently my tachometer at idle surges from 150 to 1000 rpm in a constant loop, problem gets worse the longer the engine is on, until it stalls.

I have had my car at my mechanic's shop, here is what has been done and tested...

Replaced Alternator with Denso Reman (there are no new alternators outside of high performance replacements), new Interstate Mega-Tron+ 800 CCA Lead-Acid battery, cleaned terminals (no corrosion but cleaned, padded and treated anyway), OBD codes read (none given), electrical drain test showed no unusual parasitic drain, vacuum leaks ruled out, power steering flushed and filled, transmission flush and fill, oil change (Valvoline Full Synthetic High Mileage 5W-30 /w Mobile 1 extended protection oversized filter).

As you can tell, I have spent some time and money on this car, and my problems are not going away and the car is currently undriveable...

I am now at the point of removing my ECU and sending it out for repair..

Has anyone sent their ECU to LSCowboyLS for repair?

I have seen his extensive posts on ClubLexus, with him and Yamae, I just wanted input here, thoughts?

LSCowboyLS Contact Info

[Yamae]

When I had begun to explain how those QAS capacitors used in the ECU were risky several years ago, almost no one has paid any attention nor understood me. May be because my English was limited. But LScowboyLS was the first guy who understood me well and also he had succeeded to fix his LS400's ECU. Then he decided to started the thread," All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)".

As a Japanese engineer myself and a guy who knows some behind scenes of the car, I recommend you to replace those capacitors for a preventive measure. If you are not good at the soldering work, ask him for a help. He does have good knowledges, skills and the experience. My intention is to keep our precious LS400/Celsior on the road longer. One of the most serious problems is the ECU capacitors issue and I suggest you to replace those before the board is damaged by the leaked liquid which is very strong alkali.

 

[Spartan0536]

 

When I had begun to explain how those QAS capacitors used in the ECU were risky several years ago, almost no one has paid any attention nor understood me. May be because my English was limited. But LScowboyLS was the first guy who understood me well and also he had succeeded to fix his LS400's ECU. Then he decided to started the thread," All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)".

As a Japanese engineer myself and a guy who knows some behind scenes of the car, I recommend you to replace those capacitors for a preventive measure. If you are not good at the soldering work, ask him for a help. He does have good knowledges, skills and the experience. My intention is to keep our precious LS400/Celsior on the road longer. One of the most serious problems is the ECU capacitors issue and I suggest you to replace those before the board is damaged by the leaked liquid which is very strong alkali.

 

Thanks Yamae, I just wanted to make sure I am sending my ECU out to the right person, your insight means a lot, you are an extremely valuable member of the Lexus community. I should have my ECU sent out to him today with priority shipping, thanks again for the insight.

[Exhaustgases]

Something else that degrades and has a recommended replace interval is the O2 sensors. And if you go to the clublexus site there is a good bit of info on the idle air control motor bearings that can cause some major drivability problems.

[Alexander the o.k is back]

These seemingly unrelated problems sound like the old chronic Ls400 trunk hinge issue: http://us.lexusownersclub.com/forums/index...showtopic=50087

"This same type of problem happened to me about a year ago. This smooth world class car started balking, cutting out, lurching, wild rpms, dash flickering, radio went out when hitting the brakes, just seemed ready for the junk yard. It happened all of a sudden. No warning. Now it's smooth as silk w/ 255,000 miles on it. Open the trunk. On the left side you will see a wire harness on the left hinge. After repeated openings and closings the wires inside that harness become fatigued and frayed. Then they start shorting out. Then sputtering, and stalling. This is a design flaw and lexus knows it. If this describes your problem, then remove the plastic bracket on the left hinge, strip down the harness, untwist all the wires, re-connect, then re-tape.. Don't assume they are good- strip them down and examine them. Make sure to leave off the hinge bracket that ensures tension on the harness. Just let the whole mess swing free and loose. In my case, problem solved, and no spending thousands of dollars in diagnostics, parts, and tech snafus. Best of all, it's free. Takes about 30 minutes." Post back what you see at the hinge.

Alex

[Spartan0536]

 

These seemingly unrelated problems sound like the old chronic Ls400 trunk hinge issue: http://us.lexusownersclub.com/forums/index...showtopic=50087

"This same type of problem happened to me about a year ago. This smooth world class car started balking, cutting out, lurching, wild rpms, dash flickering, radio went out when hitting the brakes, just seemed ready for the junk yard. It happened all of a sudden. No warning. Now it's smooth as silk w/ 255,000 miles on it. Open the trunk. On the left side you will see a wire harness on the left hinge. After repeated openings and closings the wires inside that harness become fatigued and frayed. Then they start shorting out. Then sputtering, and stalling. This is a design flaw and lexus knows it. If this describes your problem, then remove the plastic bracket on the left hinge, strip down the harness, untwist all the wires, re-connect, then re-tape.. Don't assume they are good- strip them down and examine them. Make sure to leave off the hinge bracket that ensures tension on the harness. Just let the whole mess swing free and loose. In my case, problem solved, and no spending thousands of dollars in diagnostics, parts, and tech snafus. Best of all, it's free. Takes about 30 minutes." Post back what you see at the hinge.

Alex

I think you might be onto something, you are not the first person to report this either, and my issue just came out of the blue.

My mechanic just did a fuel pressure test, no loss of pressure, engine just died and the car turned right back over. It will give a rough idle and want to die, and will die even if the accelerator is pressed.

I am having intermittent issues with my A/C system turning on and off randomly as well, and I have seen others state this as well..

Interesting that it would come from the trunk wiring, I will most definately look into this and if it is the cause I will certainly do a write up.

Edit: Also your link does not work at all, no page found error is the result.

[Alexander the o.k is back]

Good luck with it. Since there are no traceable codes to to pursue, the problems are multiple, unrelated, and intermittent- all this points to a short in the system. Or a faulty ground.
Just my 2 cents.
It looks like you've spent close to a $1000 trying various things w/ no result, so why not try it. Best part is it will cost nothing, can be done in 30-40 minutes, and if they're good, you can rule that out and look at yours grounds. I think there are at least two or three, not sure where tho.
I've owned my trusty ls400 for about 19 years and can safely say it is the absolute best car I've ever owned. Hands down.
I may do a post showing what items I have NOT had to even replace in all those years, including the original fuel filter and pump! Still have the originals on there. Front struts- never been replaced. (well they may have been after the deer fiasco but that was 17 years ago!)
And on and on.
Just amazing.
Love this car.
Please let us know what you find since that helps us all. With the LOC as a resource you WILL be successful.
Best of luck.

[Exhaustgases]

And in a year or so when you have transmission trouble, it will be from that fluid that was used.

[halmor92]

I am original owner of 1992 SC400.  Must replace front seatbelts and cannot find a supplier.  Help!

 

[sha4000]

Your best bet is to find some decent ones out of a car in the junk yard. I doubt that they are still making seatbelts for your car.

http://www.car-part.com/cgi-bin/search.cgi

[Spartan0536]

Update....

My mechanic gave up and just gave the car back to me...

I drove it home and around town for a few miles at a time over the course of 2 weeks.

Since then I have driven 400 miles in the car without an issue.


What I am thinking is that it needed at least 50+ miles of driving to "re-learn" how to operate and idle correctly, I have been told rebuilt ECU's need a break in time, given the age of the ECU and car this might explain the 50+ miles needed to accomplish this.


BTW LSCowboyLS does some great work and is more than willing to answer any questions you might have, damn lucky to have a guy like that working on cars.

[billydpowell]

 

LSCowboyLS Contact Info

Edited October 25, 2017 by billydpowell
lscowboyls info