Friends evo is running rough but only when the motor is cold. The widebad reads very lean and it will die if it doesn't have throttle. This started happening right after he washed it with a pressure washer. Some water was sitting down in the valve cover for a few min. It is not throwing any codes. Any ideas what it could be?

 

You might have water in the fuel tank, I had the same issue occur after pressure cleaning the engine bay.
I bought some water evaporator that you add into the fuel tank and it gets rid of any water that could be in there. Give it a try and see if that works for you.

 

try some "Heet" in the tank

 

I will tell him to give it a try.

 

Drained the tank. back to normal...

 

so draining the tank solved the start up issue?? i am having almost the same thing when cold with the lean AFRs and it takes time till it adjust and start running normal.....

 

yea it must have had a little water in the tank. It runs just fine now. I didn't think it was safe to let it run like that so i gave it some throttle. This was at like 18.2:1 and it may have been lower as that is as far as this wideband goes.