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Code P0401 -- EGR insufficient flow, 1997 F150, 4.6L

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  #31  
Old 04-11-2006, 04:06 PM
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DPFE sensor needed replacement - twice

In appreciation of this fine thread, I will post my experience over the last year, solving problems involving EGR flow. Cutting to the point, both incidents were resolved by replacing the DPFE sensor. Yes, that's right...twice.

I own a '98 Ford Club Wagon, with 5.4L Triton V8. About 85 Kmi.

In April 2005 and about 75Kmi, I resolved to fix a problem that had been bugging me for 6 months. I was experiencing sputtering engine at low RPMs...pinging at freeway speeds...and a P0401 (insufficient EGR flow) code. After cleaning EGR valve to no avail (it was only a bit black inside), and observing of vacuum command to EGR valve with vacuum gauge, I replaced the DPFE sensor. This fixed the problem.

To this day, I believe I was actually experiencing EXCESSIVE EGR flow, though my computer reported the opposite. Moral? Take OBD-II codes with a grain of salt.

Within a few months the same sputtering and pinging symptoms returned, only this time with a P0402 (excessive EGR) code. Rather recently, I replaced the DPFE sensor to cure these problems, after tolerating them for months...and failing a smog test. To my amazement, the first replacement (90 day warr; mfgd by Wells, bought at Autozone) had long failed, though subtlely. The second replacement (1yr warr; mfgd by Borg Warner, bought at Pep Boys) continues to work great. No sputtering, and no error codes. Smog test passed.

Moral? Though my original DPFE lasted 70Kmi, the second died after about 3Kmi. You never know!

I can visualize no external reason why a DPFE should die. Obviously, some "cause" would be of great interest to me, as the second replacement is in line for failure, then, isn't it? If anyone knows what kills DPFE sensors, please let me know. Meanwhile, I'll continue to assume that they only self-destruct.

Last edited by JohnPeter; 04-11-2006 at 04:50 PM. Reason: forgot something
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  #32  
Old 04-11-2006, 06:50 PM
Redwing454 Redwing454 is offline
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Why That Dirty TB

Been here and fixed this problem before. Remove the air cleaner housing and have a helper (with engine off) put the pedal to the floor. With a flashlight look in TB (throttle body) and you will see the problem. Use a can of TB cleaner and clean carbon build up. Sometimes the TB may need to be removed and the intake to Tb port thourly cleaned. But carbon build up is the problem. What a great design take dirty nasty exhuast and pipe it into the Tb. What do they think will happen. BAd design.

Redwing454
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  #33  
Old 04-11-2006, 10:12 PM
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Redwing,
Thanks for adding to the thread...which I didn't read in its entirety. So I'm not sure what problem you were referring to, when you cleaned your throttle body.

What engine and model year do you have?

I happen to have a 1998 5.4L Triton V8, with 82 Kmi., that just barely passed the NOX test in my recent California emissions test. Do you know how to improve on that? I cleaned my EGR valve last year, without any seeming improvement. One way or another, combustion must be hotter in order to produce more NOX. Maybe it's an indication of excessive leanness?

Any comments appreciated.
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  #34  
Old 04-12-2006, 07:16 AM
Redwing454 Redwing454 is offline
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Hi John

Hi John The TB on these ford engines 4.6 and 5.4's have a carbon build up problem. Also i would try replacing you O2 sensors if you have more than 50k as these read exhuast gases and change engine mixtures.

Good Luck
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  #35  
Old 02-17-2007, 06:59 PM
mherndon mherndon is offline
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I removed my throttle body and after 175,000 miles on my 99 5.4, the ports were all open. I cleaned up the black crud coating on everything, but I don't see how the huge ports can be 'clogged', and if they are, don't remove the throttle body, you are wasting about 2 hours. Just pull off the EGR and shoot some chemtool B-12 down the hole. You can use a toothbrush too if you like. Or you could push about 6 inches of coathanger down the port to check for clogs. There is no hocus pocus here, every 'port' has an access to the outside world where you can put the chemtool pipette and blow your crud away.
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  #36  
Old 02-18-2007, 01:19 PM
foster39 foster39 is offline
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my 97 4.6 160k had the same code at the same miles. the egr port gets clogged up, take the throttle body off and clean the port with carb cleaner and small wire brush then clear the code. should be good for another 100k, just did the heater core tons of fun

Last edited by foster39; 02-18-2007 at 01:46 PM.
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  #37  
Old 02-18-2007, 01:36 PM
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Welcome to the forum foster39
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  #38  
Old 02-18-2007, 01:45 PM
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thanx hope to be some help
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  #39  
Old 03-04-2007, 09:17 PM
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Curious, what would the computer do if the egr port is completey blocked off on the TBody side & the egr itself is still good(not stuck open) & is hooked up.??? I woundnt think it would set a code due to the EGR valve is functioning.
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  #40  
Old 06-05-2008, 01:17 PM
archtrek archtrek is offline
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I'm have a similar problem with my 97 F150 with the 4.2 V6. I've replaced the DPFE and the EGR and the light comes back on after 30-60 miles of driving.
Does anyone know were I can download a schematic of the emission system? I've read through the repair items here and am unclear on some of the items mentioned. I'm not real familiar with the newer models and working on emission related issues.
The truck had the motor and trans relpaced within the last two years, but used a short block.
Thanks for any assistance.
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  #41  
Old 06-05-2008, 03:11 PM
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Vacuum leak and DPFE sensor

Archtrek, if you're still seeing fault codes, you might suspect your DPFE sensor AGAIN. How old is it? I had one fail within months. A vacuum gauge in the right place can offer hints, but I cannot remember the vacuum circuit at this late date.

In 2006, I barely passed my NOX test. In 2008, I passed with a higher margin. The difference, mechanically? In the interim, I discovered a vacuum leak. Apparently, it was subtly evident for years, finally getting so bad that I could hear it and so bad that it caused the car to stall.

So don't forget to look for vacuum leaks. The formed fittings, (elbows, etc.) are the most likely to fail. My failure was easily accessed behind the doghouse, in my van.
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  #42  
Old 06-05-2008, 03:26 PM
archtrek archtrek is offline
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Low Flow

The DPFE has been on for several months now, but got the code within 30-60 mile of replacement.
I'll look for vacuume leaks and let you know.
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  #43  
Old 06-05-2008, 04:01 PM
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Maybe you bought a bad DPFE
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  #44  
Old 02-28-2010, 06:48 PM
sthurman sthurman is offline
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I have a 98 F-150 that starts and idles just fine If I gently press the gas about halfway the engine will rev up normally but if I step on it as if I were accelerating ont a highway the engine bogs and backfires I have swapped the IAC, TPS, MAS, DPfe? sensor, EGR Solenoid, checked the vacuum line and still the problem persists somebody mentioned the coild packs is there an easy way to tell?
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  #45  
Old 02-28-2010, 07:23 PM
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Unhappy Flat Spot

Quote:
Originally Posted by sthurman View Post
I have a 98 F-150 that starts and idles just fine If I ... step on it as if I were accelerating ont a highway the engine bogs and backfires...somebody mentioned the coild packs is there an easy way to tell?
That's a good old-fashioned "flat spot." The backfire is blatant evidence of leanness. In the old days carburetors squirted gasoline down the throat of the venturi to compensate... I don't know exactly how this is accomplished in a 1998 model...

I also observed flat spot to be symptomatic of very late engine timing, decades ago.

I would say that any sensor that tells the computer when to suddenly enrichen the mixture should be suspect.

Leanness is more than just an annoyance. A lean engine can oxidize (i.e., "burn") valves, causing major cylinder head damage. So consider this annoying flat spot to be a warning... prescient of even more serious problems if not remedied.
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