I'm probably about to be in a world of hurt for posting this, but here we go. I bought a 1999 LS400 from Copart and decided to take it to a rallycross yesterday. The car had a VSC and ABS light on when the transporter dropped it off. Trunk got smashed in the wreck. I have Trunk Open, Check VSC, Low Washer Fluid, and Brake Wear messages coming on. The first run went flawlessly, full power everywhere. My friend was co-driving and he said it didn't have any power. On my next run the first ten seconds went great, then it activated a rev limiter at 3500rpm. We kept fiddling with it throughout the day and in the morning we found if we shut off the car and popped the hood in between runs it would give us a complete run without issues. At this point my working theory was that the trans fluid was getting hot and putting the ECU into limp mode. In the afternoon it was very hit or miss whether or not letting it cool would result in full power for the run. We could throw it into neutral on course, shut off the motor completely and restart it, put it back into 2 and it would have power again. Sometimes for the duration of the run, sometimes for 15 seconds. The rev limiter would vary anywhere from 5000rpm (which was still somewhat usable) and 3000rpm (which basically killed all power). After the event I let it cool down for an hour, started it up and it hit the limiter immediately. Cycle the ignition, it went away for a bit. We had shorter tires on the rear, so I put the stock ones back on to match the front, no change. The limiter sound more like an ignition cut rather than a fuel cut because of the crackling, but that may just be because the four rear mufflers have been cut off. Given that, I also suspect there may be a grounding issue somewhere. At first glance everything appears tight.

So now my working theory is that a wheel speed sensor is bad, and even though the VSC is inactive, the computer is still getting all the information and is thinking something is wrong and shutting down all the fun. Whereas if the VSC was working properly and it were turned off via the button it would at least know what's going on and have no issues. Any thoughts?

 

I would scan the code and start from there. Check VSC comes on for a multitude of things. These throttle body is a hybrid and use a motor in them to modulate and cut power when it loses traction for VSC. Could have a bad throttle body motor. Try cleaning the connectors first with dielectric grease, that eliminated my throttle body code I was getting when it was really cold out in Michigan and hasn't come back in over a year and a half now.