2001 SuperCrew F150 V8 4.6L
140K miles (highway)

Problem: P0401 code (insufficient EGR flow) *Main problem!*
Light blue smoke on startup (started 137K) probably valve seals.
Uses a little oil now. About 1qt in last 3K miles.

History: 100K Replaced spark plugs
125K (had P0401 code). Replaced DPFE and EGR valve (EGR
valve was still good). Cleaned EGR pipe. Cleaned Throttle body
which was completely clogged on the EGR ports.
Reset code and it worked fine until now!
137K IAC valve went crazy and was replaced
140K P0401 code came back!

Does anyone have any idea what I should try next to remove the P0401 (insufficient EGR flow) code? I checked the following things this weekend:

1. All hoses seem fine and have vacume.
2. DPFE hoses are clean and both have air flow.
3. EGR valve will hold vacume and the engine runs rough when it is engaged with vacume at idle. (i think that is one of the tests)
4. The hose to the EGR has pulse vacume at idle and the EGR solinoid valve has vacume to it also.
5. I removed/inspected the throttle body again anyway and it appeared "clean", no ports clogged.
6. Reinstalled everything and code came back after about 75miles.

What am I overlooking or have not tried? Any help would be appreciated!
Thank you in advance for your help.

Richard Grimes

 

Don't think this will help but this is the test you mention in item #3. It sounds like your ports are still clean. Just a note to clarify.

Remove the vacuum line from the ERG Valve and cap the hose. Start the engine and let it idle. Then apply vacuum (outside source) to the ERG Valve. The engine will stumble or stall if the ports are clean. If the engine continues to idle without change the ports are blocked and need to be cleaned. I cleaned mine in about an hour it's not that big of a deal on the 4.6L

Good Luck

 

]

The EGR valve should NEVER have vacuum to it at idle. The EVR solenoid should ALWAYS have vacuum to it.

Unplug the electrical connector to the EVR solenoid and see if there is a change in the vacuum at the EGR valve. If there is no change, the EVR solenoid is defective. If the vacuum goes away, it calls the PCM into question.

All that said, those symptoms SHOULD flag a P0402...but you have a P0401.

Steve

 

Sounds like your EGR is bad or clogged. If it runs rough at startup then its stuck open. The other option is the DPFE sensor that controls the EGR valve. They are a known problem with Ford trucks.