I've got a 1988 Honda Prelude 2.0 SI. I know what is causing the nox to be high, however I can't find a fix to the problem. The solenoid that gives vacuum to lift the egr will don't turn on under working conditions. With power applied to it from the battery, it will create the vacuum required. We've even changed out the ECU for the car and there was the same problem. What are possible causes that may be causing the computer to not tell the solenoid to turn on.

 

check ALL of your vacuum lines, then if you think they are all on, go back and check AGAIN.