Hikar

I bought this LS400 last month, when i bought it it smoked like crazy at start up then got better but still smoked a lot while driving, limp mode and low power, thought it needed a new capacitor because it was leaking, so I had it replaced, installed it this friday and it didn’t fix anything, still smokes like crazy and in limp mode, runs horribly, what could it be??? previous owner said it could be leaking valve stem, any wise man got an idea?? Also heard tapping or something like that for a couple seconds while it was on. (131k Miles)

Yamae

Sounds like an ECU related problem. I worry that copper traces or parts nearby capacitors are damaged like this way. Have you checked them carefully enough. Sometimes, the internal layer is damaged when capacitors were not replaced quickly after the leak was started.

Hikar

It does appear to be damaged, the capacitor was replaced but the traces dont look good, what do you think? is it salvageable? I cant upload the picture but i could email it to you

400fanboy

You can upload images to the forum, or, use a site like imgur.com to host them and post the link to. Try and get pics, Yamae is the world expert on these things, it will help a lot.

You can also electrically test the ECU with this method:
https://www.clublexus.com/forums/ls-...-by-yamae.html

For what it's worth, you can hot swap with a known working ECU (model # must be exact match). This could be used to test, if you have a friend with the same car for example. Or, eventually replace it if your unit is actually perma-damaged.

Hikar

ECU Copper Traces
this is the video of the effected copper traces, they look pretty bad, in your guy’s opinion is it the culprit of my problems? is it repairable?

Yamae

I still can see a QAS capacitor printed PR(M) in the video. This alone is a big problem still. Also copper traces are badly damaged. Those can't be fixed by an average DIYer. Even a professional may say, "I can't guarantee to fix".

Incidentally, does your ECU have the updated firmware? If not, it would be smarter to purchase a good working ECU which has the updated firmware.

Hikar

Yes, i bought a new ecu, it runs better now but it still smoke a lot, here’s the video of the smoke, it smells like gas and sulfur, what should i do, i heard it could be the power steering valve thing.

Yamae

If it's caused by the valve, I'd suggest you to read this thread and try to use a bolt M14x1.5 for the confirmation.