Ongoing VSV, or something else?

[Mile_High_Flyer]

After various suggestions, I have replaced all the hoses shown above, on the VSV (VACUUM SWITCHING VALVE) for EVAP etc, because they were hard, and possibly leaking, but of course, not the other parts. The VSV appears to be fine, the resistances are within spec, the valve opens and closes properly after cleaning, when 12 volts is applied, I can blow through it when open, but not when closed, I tried blowing through the tube off the canister line, unsuccessfully as expected, instead of using smoke. After I left the shop where I bought the above hoses, without having done anything, it came right, all was beautiful! I did the hoses after I got home, and it was still good. However, yesterday, it all started turning to custard again. Today was worse. All the usual, bad idle, fuel smell, reduced fuel economy, not-so-smooth gear changes etc. I'm at a bit of a loss as to what to do next! I haven't refueled, as the tank is about 3/4 full. When I did fill up the other day, I stopped as soon as the nozzle clicked off the first time, so the canister doesn't get contaminated. Wondering whether another reboot by disconnecting the Battery for half an hour, might help make things right again once the computer gets itself sorted, after some mileage, hopefully not just temporarily. Or should I drive it some more first, and see what happens?

After that, it got worse. A lot worse! I then removed the PCV valve. It rattled, as it should, but I still cleaned it with throttle body cleaner. I couldn't blow through it one way, but could the other way, and the rattle was slightly louder, and appeared to be more free. I then reinstalled it. Its hose appeared to be fine. I then looked at the 2 Pressure pulsation dampers. Couldn't see any signs of fuel leakage. I then went for a very short run, but it didn't improve. When I got back, I turned off the engine and looked at the dampers again. The screws had risen up. So presumably the dampers are working, with no diaphragm leakage as there was obviously still pressure there. So, I rebooted by disconnecting the Battery for half an hour again. It then came pretty well right and kept improving slowly, as has always happened previously, but then, after a time, it went bad again. I then blew through the line back towards the canister, then sucked it, and the line was free. I assume that's how it is supposed to be. The fuel tank is pressurised when the fuel cap is removed. We have also checked the VVT solenoids, and they appear to be working correctly. Another reboot! This time it hasn't had enough time to go wrong yet, but I expect it to probably do so soon! I'm wondering if it could possibly be the ECU computer?

When it's starting to go wrong, the first indication usually seems to be the rougher gear changes, then the fuel consumption starts going up, and after a while, the exhaust pipes start to go black. There are no CEL dash lights, and my tester doesn't show any codes.

A couple of days later:
Here we go again! It's started having slightly less smooth gear changes, and the exhaust pipes are starting to blacken! It never seems to lose power, even when it's pretty bad. it can accelerate hard, right up to gear change revs. I'm in two minds as to whether I should reboot again now, or continue driving and see what happens. One time it got really bad, it was so rich it was smoking and even missing. Another time, it came right by itself, until it went out again! It seems it always comes pretty well right, albeit temporarily after a reboot, usually for between 1 and 3 hundred kilometres.  I did reboot again, and it lasted about 200km before starting to go bad again.

As a reminder, it's an '04/'05 LS430 right hand drive imported from Singapore to New Zealand. Everything in English, not Japanese. Done about 230 Km.

This was obviously written over a period.

Any more suggestions?  Please!!

[Malc1]

Keith welcome to the Club 

there’s a few guys here with bundles of Ls430 knowledge that will engage soon I’m sure

Good luck  

Malc 

[Mile_High_Flyer]

Thank you Malcolm. I was a member some years ago, but either my membership lapsed, or went AWOL!

Cheers, Keith.

[Malc1]

Try Steve2006 here. He’s an ace with the Ls430 

Malc 

[steve2006]

There have been reports of the engine ECU failing on the LS430 by one of your own countrymen and giving the symptoms you have.

What diagnostic equipment are you using for the code read as Toyota Techstream is the preferred one?
 

Take a look at the link below.

 

[Mile_High_Flyer]

Thank you Steve. I have emailed them, but don't expect to hear back from them for a few days, at this time of year.

My OBD2 reader is a generic one. I had a place with a professional reader check things out, but nothing specific was found.

 

[steve2006]

No problem, pleased to help 😀

When ECUs go faulty they have been known to stop communicating on the CanBus and the diagnostics port so basically stop talking to code readers also.
Please keep us updated as to the diagnosis and cause.

P.S. What initially made you go towards the EVAP system as being the cause?

[Mile_High_Flyer]

It was the forums at Club Lexus USA  For example the following.  I don't know if you can get there if not a member,

DIY LS430 VSV (VACUUM SWITCHING VALVE) for EVAP cleaning / replacement procedure

https://www.clublexus.com/forums/ls-3rd-gen-2001-2006/920509-diy-ls430-vsv-vacuum-switching-valve-for-evap-cleaning-replacement-procedure-4.html

[Mile_High_Flyer]

Since then I had to reboot a number of times. The last few, before reboots, I did the following distances. 400km, 300km, 56km, now I'm 2500km since last reboot and she's behaving beautifully. I didn't do anything else, so I have no idea what changed. Great mileage, clean exhaust pipes, beautifully smooth gear changes.  I was about to have the ECU computer checked over by an expert here in New Zealand, but it was holidays so it couldn't be done at the time, but that's when it came right!

I wait in trepidation to see what happens!