Goesta

Hi! I have a 1994 LS400 and I have had some strange issue where the car drives absolutely fine for about 5 minutes, but then I get a check engine light and TRC light. I lose almost all power and the car won't downshift. These lights flicker sometimes, almost like theres a bad connection somewhere. And when I listen in the engine bay, with only the ignition on, the vacuum shift valve clicks, and it seems to click in time with the engine light.

I have had issues ever since my uncle left the car jumper on 24 volts without me noticing. I left the door open one day and accidentally put 24 volts to the battery. Since then I have replaced lots of various things such as a rebuilt ECU, battery, O2 sensors, fuses, TPS sensors and more.

Any ideas on what could be the issue? Also any details on how the vaccum shift valve might impact the car would help.

CELSI0R

Since you have a CEL and a TRAC light on, start by pulling the codes so you can narrow down where the issue might be:
http://www.lexls.com/tutorials/intro/codereading.html

The VSV is part of the emissions system for the car, and may be coincidental that it clicks or not. It's hard to say at this time.

Goesta

The thing is I don't get any codes.. I can start the engine and it fires up right away, but if I don't give it some gas it dies immediately. It also feels rough sometimes when I keep the RPM constant, like a stutter, I also think it smells like it's running rich. I recently cleaned the maf sensor but it did nothing.

Could it be misfire? I feel like I should get codes if it is.

Goesta

I removed the maf sensor and tried starting without it, and it can now idle!

It drives super slow and idle is a bit wonky, but hopefully that's just cause it's missing the value from the sensor?

cj98ls

I did a google search for EGR VSV and this link popped up from the clublexus sc400 forum, a pdf of the diagnosis and repair of the system. Might help you narrow down the systems you have to check.
https://www.google.com/url?sa=t&rct=...W&opi=89978449