I have a 2004 LS430, 242000 miles
For a year now sporadically the car will lose power with foot on the accelerator. The car will stall, turn ignition switch off and it fires up no problem. This will happen again, and there is hesitation as if water is in gas. I have noticed a sulfur smell when it gets really bad.
Tech that does the work can’t determine issue
I have read replace MTS and/or TFA unit???
Any idea on what may be the issue?

 

any codes? misfires?

 

The sulfur smell indicates either a clogged/damaged CAT or else something is flooding the CAT with too much fuel.
Difficult to analyse if there are no codes. Normally the emissions system is the first to throw a code when something is not right.
Is it possible that someone has "eliminated" the secondary O2 sensors or otherwise fiddled with the emissions system?

 

If possible when it happens stop car and leave on and go back to exhaust and feel how much is coming out. Sounds like cat is starting to get clogged. Should be getting some kind of codes but system could have been tampered with to bypass or flooded with fuel as mentioned.

 

No Codes at All. Dealership and Mechanic are saying once I turn off car and cut it back on codes are lost. Is there a device I can buy that will capture the codes?

 

Big Boomer, thanks for the reply. I use Toyotech here in Ga and they do all the work. Pretty sure they would not do that. Is there a device that I can purchase to capture codes? Toyotech mentioned that once I turn car off and turn it back on, the codes are lost. They did have a computer guy come in and he say something and did something. The problem still returned. I will keep in mind the CAT when I talk to Toyotech.

 

With Techstream a health check can be done and show history and pending codes. Did the dealer do this? Does the check engine light come on? Did you do as I suggested and while running with problem check exhaust flow? There are numerous devices to plug into OBDII port for live monitoring.