i have a 97 f150 4x4 with 4.6w. I bought the truck new but haven't been able to get it to pass inspection for a few years due to P0401. I have removed throttle body to clean carbon from ports, replaced EGR valve, DPFE and EGR tube. I have spent the last few weekends replacing the passenger side exhaust and noticed when I removed the fender lining that one of the mounting tabs on the vacuum tank inside the fender is cracked. Wondering if the tank is cracked as well. What's the best way to check this out?

 

Have you looked at the EGR solenoid?




When you cleaned the throttle body, did you pull the elbow and clean out the passages in it? Does the EGR valve pass a suck test?

 

Solenoid has been replaced. Explain EGR valve suck test please.

 

Remove the vacuum hose from the EGR valve, connect a piece of vacuum hose to it and suck on it. It should start running rough and may even stall.

Did you clean the elbow passages?