ehless400

Hi all, new member here who needs some expert feedback:

I have continuously owned LS400's since 1994 ('92, brand-new '98, '95). My current LS is the '95 with 185K miles:

I bought the '95 from its original, meticulous owner 6 years ago with about 140K miles on it.

Soon after I bought it, the check engine light came on and the codes told me that 1 or 2 oxygen sensors needed replacement. I immediately installed OEM sensors, but was disappointed months later when the check engine light re-appeared indicating a bad front cat and a misfire caused by the clogged cat. Being that I just went for good money to replace the sensors and didn't feel the mis or notice any decreased performance (other than the usual 14mpg), I ignored the light.

Year after year, the car passed emission inspections further encouraging me to continue on with my head in the sand.

Recently, after an 80 mile highway cruise at 75mph, the car stalled, without warning, as soon as I came to a complete stop. I restarted the car, put on the climate control to increase the idle, and power-braked the whole way home from the highway so that it wouldn't stall again. The next day, the car ran fine.

Since then, I have only used the car to run around locally and all has been normal. I never attempted to get back on the highway until today when I got another scare: When I got up to 45mph, the car began to shake (almost as if I had a flat tire) and lose power (I assume it was the misfire finally making itself known). I exited the highway, and there she goes again, right back to normal, with no signs of the misfire, and holding power on her own.

At this point, I am done procrastinating and need to address the issue and fix the problem. After reading these forums, however, I am no longer convinced that the cat(s) need to be replaced.

So here I am, looking for some advice from my fellow, loyal LS400 lovers:

Has anyone experienced these issues? If so, please share your lessons learned in diagnosing and remedying the problem(s).

Could it be that the codes from AZ are not accurate?

Could it be that a simple fix like replacing the coolant sensor can solve these problems (as has been discussed in these forums) ? Or maybe it is the faulty ECM caps (which has also been discussed in these forums) causing the problems?

Could it be anything other than that?

Lastly, if it is that cat causing these problems, any recommendations regarding replacing the cat(s) would be greatly appreciated.

Thanks

billydpowe

iTrader: (1)

search and read and you will find out a simple gasket leak can cause these problems/codes. Then come back and tell us what you have found out and what your caps looked like, maybe a photo...

Jspec603

If the problem does not go away, you can always have anti-fowlers installed between the O2 and the exhaust pipe. This will trick the car into thinking it has the proper flow by removing the majority of the O2 sensor from the exhaust stream. It is not the most proper way to do it, but it will make the light go out.

Also, I have come to find that it is an ECU problem for the stalling issues. I also have a 95 I recently bought and it is doing the same, stalling only after long drives. I have not replaced mine yet, but everyone is recommending me to do so. There is a specific part number you'd want to look for on the ECU's for this. I do not remember them, I'm sure others will chime in.

Shmee

iTrader: (3)

So the CEL has been on for the past few years?
Do you still have the clogged cat in the car?
Have you scanned the car or pulled the codes again recently to see if you are getting any new codes as well?
What maintenance have you done to the car recently and since the problem started?

I'm guessing if you stuck your head in the sand over this problem, you probably neglected some of or a lot of your maintenance over the past 40k+ miles...

My suggestion is

#1. Check the codes
#2. Post codes

From there better advice can be given about where to start.
Anything other than that will be nothing more than stabbing in the dark...

You could have anything from your clogged cat causing the issue to a fuel pump going out or coil(s) cutting out or something else!