I have a 1997 F-150 with 4.2 litre engine. I replaced the long block in DEC 2007. Intake and ports cleanded at change. I use an Innova 3100A Scan Tool and it has captured freeze frame info.

To date I have changed the DPFE, EVR, EGR Valve, Checked Manifold ports again. Vacuum lines are fine. It still throws a DTC P0401 to my scanner but sometimes the CEL does not light for a day or two. I am at wits end.

Freeze frame info follows along with truck data. For some reason it never completes test of EGR or EV systems. Help would be greatly appreciated.


VIN: 1FTDF1720VND16098
Year: 1997
Manufacturer: Ford Motor Company
Make: Ford
Model: F150
Engine Type: V6, 4.2L (256 CID); SOHC 12V
Tranmission: Automatic
Trim Level: Standard; XL; XLT; Lariat
License Plate: APPLIED
Mileage: 198000
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
<o></o>
<o></o>
=== Pending Error Code(s) ===
Error Code: P0401
Possible Causes:
<o></o>
<o></o>
<o></o>
Freeze Frame Information:
1. DTC for which Freeze Frame was Stored - P0401.
2. Fuel System 1 Status - Closed Loop.
3. Fuel System 2 Status - Not Supported.
4. Calculated LOAD Value - 56.86 %.
5. Engine Coolant Temp - 203.00 °F.
6. Short Term Fuel Trim - Bank 1 - -1.56 %.
7. Long Term Fuel Trim - Bank 1 - -4.69 %.
8. Short Term Fuel Trim - Bank 2 - -3.91 %.
9. Long Term Fuel Trim - Bank 2 - -0.78 %.
10. Engine RPM - 1,436.00 Rpm.
11. Vehicle Speed Sensor - 32.93 Mph.
<o></o>
<o></o>
Monitor Information:
<o></o>
1. MIL - OFF.
2. Misfire Monitoring - Complete.
3. Fuel System Monitoring - Complete.
4. Comprehensive Component Monitoring - Complete.
5. Catalyst Monitoring - Not Complete.
6. Heated Catalyst Monitoring - Not Supported.
7. Evaporative System Monitoring - Not Complete.
8. Secondary Air System Monitoring - Not Supported.
9. A/C System Refrigerant Monitoring - Not Supported.
10. Oxygen Sensor Monitoring - Complete.
11. Oxygen Sensor Heater Monitoring - Complete.
12. EGR System Monitoring - Not Complete.

 

Have you checked the wiring connector to the DPFE ? Might explain why sometimes the light is on and sometimes not.

 

Thanks Torkum, I think I will just double check that floppy wiring connector. And I got another idea from another post about vacuum. It seems that if there is a change in the vacuum that operates a/c ducts then this can change the vacuum to the EVR. Well that might be a possibility because the duct actuators seem to occasionally go berserk. By berserk I mean they seem to occasionally hang up or move to an all closed position so no air flows out any vents. This too might be the problem that is causing all of the symptoms. Thanks again. Will check it out.

 

Have you replaced the two hoses going to the dpfe? Or checked for a restriced egr tube at the orifice between the two hoses? Is your scan tool able to watch any data? If so, watch the dpfe voltage and remove the vacuum hose from the egr valve. Apply a vacuum to the valve (either w/ a pump or just put a hose on the valve and suck on it.) see if the voltage changes.

 

When you replaced the DPFE, did you get one from Ford or from one of the autoparts places such as Autozone? I was having similar issues, on my 2000 4.6, kept throwing the light, I even replaced the entire EGR spacer, the issue turned out to be the sensor I was getting from the parts house, purchased hte ford sensor, problem went away...

 

Had similar issue on my 97 F 150 4.6 . After chasing it for two weeks and several parts, went to the dealer. My new DPFE sensor was 1/10th of a volt out of spec. they replaced with OEM and three years later no problem I second DGMford on this part, OEM only.

 

I third DGMford on OEM only. I had nothing but problems with the Vatozone DPFE. Went to Ford no probs since.

 

DGMFord, Oddballish,tj90 thanks for the info. I bought one from Autozone but according to my digital multimeter it specs perfectly as well as the one I replaced it with. Regrettably, the parts department at MY local Ford dealership is like a combination of an Arabian bazzaar manned by the three stooges. Order a nut and get an alternator...I don't know. If I really need a Ford part I just drive the 40 miles to a good dealership with a competent parts counter.

However, I think as a result of several different postings I might be on this being a vacuum problem. That big bundle behind the battery had a very bad connection. I cleaned up the connectors silicone conditioned the rubber connectors and reassembled. With the help of a wire tie I was able to pull the connectors tight together and now for about 10 driving cycles no CEL. One posting mentioned a cycling of the A/C doors in the dash as a loss of vacuum and I had that problem also. So cross your fingers for me.

 

You don't need a dealer to get a good part. I know O'Reilly's carries Motorcraft, as do other chain stores.

Regarding your code, you can do all the testing you need with a vacuum gauge and DVOM. Here's the procedure:

1. Determine if you have a hot side or cold side problem. I consider the hot side any of the parts that exhaust actually flows through. To check this, apply a vacuum to the EGR vavle with the engine idling. It should run very rough or even stall. If it doesn't, you have a hot side problem and need to find out why. Most commonly it is a plugged passage, but occasionally will be a bad EGR valve. If the valve opens with vacuum applied and holds that vacuum it is fine and you have a restriction.

2. See if vacuum is reaching the valve. Install a vacuum guage in the line that goes to the EGR valve. With the engine under partial load and the trans in gear the gauge should slowly climb to 5-7". If it doesn't, you have a vacuum supply problem. CAUTION: the pcm doesn't always request EGR, so make sure it is before you pass judgement on this test. If you have vacuum to the valve, it should be opening and you need to test the DPFE sensor output with a DVOM.

3. If you don't have vacuum to the valve, see if you have vacuum to the EVR solenoid. From what you described I would guess that you don't. These are bad about the vacuum lines near the battery degrading and breaking apart. If you do have vacuum to the EVR, check the power and ground for the EVR solenoid.

4. If the EGR vavle, vacuum supply, and EVR solenoid check out you need to test the DPFE. You can check its output voltage with a DVOM. It should vary from less than or about 1 volt to about 4-4.5 volts at max flow.

All of that assumes that you have thoroughly checked things like the DPFE hoses, electrical connections and any obvious vacuum lines. I didn't get too detailed because I hate typing, but if you need clarification on something let us know.

If none of that checks out it might be time to take it to a pro.