01 x 4.0 P0401 only code help

[2009KVFD976]

I have an 01 x 4.0 with almost 170k on it and the cel came up P0401 is all that came up. i live in tx and the yearly emmissions inspection is due this month and it will not pass with the light on... i already replaced egr valve and dpfe sensor and cleaned the small tubes th go to dpfe sensor with a coat hanger (lots of buildup came out) still need to clean the larger tube that goes under the egr valve... anything else i can do to remedy this?

 

[2009KVFD976]

I have an 01 x 4.0 with almost 170k on it and the cel came up P0401 is all that came up. i live in tx and the yearly emmissions inspection is due this month and it will not pass with the light on... i already replaced egr valve and dpfe sensor and cleaned the small tubes th go to dpfe sensor with a coat hanger (lots of buildup came out) still need to clean the larger tube that goes under the egr valve... anything else i can do to remedy this?

Forgot to mention i sprayed carb cleaner through the small tubes leading to the dpfe sensor. is there any special way to clean the big tube under the egr valve from the exh mani? Maybe its plugged up with carbon buildup...

 

[Chikar]

There is also an EGR Vacuum Regulator Solenoid. I'm looking at a Ford diagram of the 4.0L SOHC engine and the solenoid is shown at the rear of the intake manifold.

Since the P0401 indicates insufficient flow, and the solenoid controls the EGR valve, the solenoid may be the root cause.

 

[2009KVFD976]

Any way of checking it or is it just a toss it and get another one and hope it cures it?

 

[Chikar]

I just got an e-mail notification of your post/question on my phone.

I'm not home right now...Friday night

But I'll look into any test procedure that might be available on Saturday.

 

[Chikar]

I haven't been able to find any specific tests for the Vacuum Regulator Solenoid. The description below gives an explanation how it works which may point you in the right direction.

I'd suggest a continuity test with an ohmeter to ensure the circuit is complete within the regulator. Sorry I can't give a better answer.

Differential Pressure Feedback EGR System
The Differential Pressure Feedback EGR system consists of a differential pressure feedback EGR sensor, EGR vacuum regulator solenoid, EGR valve, orifice tube assembly, powertrain control module (PCM) and connecting wires and vacuum hoses. Operation of the system is as follows (Figure 80) :

The Differential Pressure Feedback EGR system receives signals from the engine coolant temperature (ECT) sensor, intake air temperature (IAT) sensor, throttle position (TP) sensor, mass air flow (MAF) sensor and crankshaft position (CKP) sensor to provide information on engine operating conditions to the PCM. The engine must be warm, stable and running at a moderate load and rpm before the EGR system is activated. The PCM deactivates EGR during idle, extended wide open throttle or whenever a failure is detected in an EGR component or EGR required input.

The PCM calculates the desired amount of EGR flow for a given engine condition. It then determines the desired pressure drop across the metering orifice required to achieve that flow and outputs the corresponding signal to the EGR vacuum regulator solenoid.
The EGR vacuum regulator solenoid receives a variable duty cycle signal (0 to 100%). The higher the duty cycle the more vacuum the solenoid diverts to the EGR valve.

The increase in vacuum acting on the EGR valve diaphragm overcomes the valve spring and begins to lift the EGR valve pintle off its seat, causing exhaust gas to flow into the intake manifold.

Exhaust gas flowing through the EGR valve must first pass through the EGR metering orifice. With one side of the orifice exposed to exhaust backpressure and the other to the intake manifold, a pressure drop is created across the orifice whenever there is EGR flow. When the EGR valve closes, there is no longer flow across the metering orifice and pressure on both sides of the orifice is the same. The PCM constantly targets a desired pressure drop across the metering orifice to achieve the desired EGR flow.

The differential pressure feedback EGR sensor measures the actual pressure drop across the metering orifice and relays a proportional voltage signal (0 to 5 volts) to the PCM. The PCM uses this feedback signal to correct for any errors in achieving the desired EGR flow.

 

[2009KVFD976]

Thanks yall for the replies!! I ended up replacing the DPFE sensor and the light hasnt came back since. ive been driving it around on the highway and in town to get the I/M monitors ready for the emissions test.

 

[2009KVFD976]

Thanks yall for the replies!! I ended up replacing the DPFE sensor and the light hasnt came back since. ive been driving it around on the highway and in town to get the I/M monitors ready for the emissions test.

Well... out of 8 monitors, only 5 were ready for testing. i had to have at least 7 to get it to pass. either egr system or evap system were incomplete. the list is as follows-
Misfire monitor-ok
fuel sys mon-ok
comp component-ok
catalyst mon-incomplete
evap sys mon-incomplete
oxygen sensor mon-ok
oxygen sensor htr-ok
egr/vvt sys mon-incomplete
Any way to get them to finish up? Only code is P1000 drive cycle test not complete. all info is from an actron cp9580.

 

[2009KVFD976]

CEL came back on with the pesky P0401 code!! My next plan is to replace the EVR solenoid. it does lack power and sucks on fuel mileage if this has anything to do with it.

 

[2009KVFD976]

I took out the upper O2 sensor and its white/tan colored. i normally see them black/dark brown. Will this help out if i replace them after all, they only have 170k on them!!

 

[2009KVFD976]

I checked my spark plugs bc of a drop in MPG amd they werent gapped right (0.030) i gapped them all at 0.054 and its worse than before!!! Esp while at a stop and i hit the gas, it spits and sputters tjen picks up pretty good. i am running motorcraft platinum plugs with new BWD wires (since 2 of the others came apart while checking plug gap) im thinkin on seafoaming it and tossing the motorcrafts amd try champion platinum plugs on it and see if it makes a difference. any ideas would b great!!