Nice when Murphy's Law not a factor!

[ozrocker]

I own a 00 Ford Expedition, 5.4 (330 CUI) V8. My Check Engine light was intermittenly on-off
for a few months. Recently staying on. I was getting a fault code for the Differential Feedback Control
Sensor. Average price $135.00. I took off top intake cover to access module, looked around a bit.
Was nice to discover that 1 of 2  1/4" vacuum lines had a small tear near connector.
Replaced both lines for $2.88 Vs. a $135.00 Sensor. No more "Check Engine"
Take that Murphy


                                                                                                                                        Oz

[icepac]

Don't worry.....your car will eventually refuse to start when the DPFE sensor shorts it's reference voltage to ground.

[ozrocker]

Common thing for the Ford ones to fail. But even when it fails, truck will run.
I even had electric plug disconnected while I went to parts store.



                                                                                                                    Oz

[icepac]

It won't run in about 50% of dpfe sensor failures.

As general manager of blue streak electronics, I did troubleshooting on at least 60 vehicles in which the car would not run if the sensor was plugged in because it was shorting the reference voltage to ground.........and the technician now wanted me to ship him another replacement ecu for the perfectly working ecu we sent him.

About 20% of those cases had the regulator burned out because it was trying to shove reference voltage straight to ground.

[ozrocker]

That's all good and fine. Mine happens to not be in the 50%, so once again
Murphy- FU



                                                                                                                                    Oz

[CAP1]

I own a 00 Ford Expedition, 5.4 (330 CUI) V8. My Check Engine light was intermittenly on-off
for a few months. Recently staying on. I was getting a fault code for the Differential Feedback Control
Sensor. Average price $135.00. I took off top intake cover to access module, looked around a bit.
Was nice to discover that 1 of 2  1/4" vacuum lines had a small tear near connector.
Replaced both lines for $2.88 Vs. a $135.00 Sensor. No more "Check Engine"
Take that Murphy


                                                                                                                                        Oz

 some of the older 5.4's, and 4.6's used to have a problem with egr passages in the throttle body clogging up, filled with carbon. they would trip this code. if you cleared the CEL, it can take 2 days, to a couple of weeks for the code to reset if that wasn't the only problem.
 one problem with those sensors, is that they get moisture in them.

 i worked at a place for about 6 months.....couldn't get outta there fast enough. i had gotten myself in a bit of trouble, due to some unfiltered words leaving my verbal dispersion orifice. i think they were concerning the intelligence of the mechanics there....the ones that thought that just because they knew how to hook up a MODIS they knew how to diagnose a car.  i was hired there as the diag. tech. i was busy, so an f250 was given to the smartest mechanic there. he pulled the dreaded p0401(i think that's the most common code on fords.), assumed a DPFE sensor, and replaced it, shipped the truck, feeling all proud of himself.
 it came back in 2 days CEL on, same code. i got it this time. he kept coming over, telling me it must be a defective part, bla bla bla. it wasn't. it was blocked passages. i got myself in a little more trouble that day. it seemed i had forgotten to wear my verbal filtering device again.   

[CAP1]

It won't run in about 50% of dpfe sensor failures.

As general manager of blue streak electronics, I did troubleshooting on at least 60 vehicles in which the car would not run if the sensor was plugged in because it was shorting the reference voltage to ground.........and the technician now wanted me to ship him another replacement ecu for the perfectly working ecu we sent him.

About 20% of those cases had the regulator burned out because it was trying to shove reference voltage straight to ground.

 in my nearly 30 years, i've NEVER seen a DPFE sensor prevent a vehicle from starting. or the old style of egr position sensor either. i've replaced more than my share of them too.

[icepac]

Well.....I saw 60 in a two year period.

You have to remember that I was the sole technical support for products sold by standard motor products and Blue Streak and diagnosed hundreds of cars per week with problems that most technicians run into only 5 or 6 times in thier entire career.

I was usually brought these issues by our vendors (pep boys, auto zone, all the big chains) after the customer had purchased multiple ecus and still had the same issue.

Remember also that the reference voltage as sent to three wire sensors is divined by the same power supply that runs the entire ecu so that any grounding of said three wire sensor reference voltage is also making the voltage that runs the ecu short to ground.

Now a two wire sensor reference voltage power supply is designed to resist to ground and grounding of that type of sensor line will only result in the readings the ecu interprets to be maximum in one direction.

That said, I probably had many hundreds of 1996 jeep grand cherokees, 1996 dodge caravans, and 1996 dodge durangos during that same period.

1996 is a nightmare year for any dodge/jeep electrical diagnostician.

Fords issues were mainly with the dpfe sensor itself and o2 sensors shorting which causes the driver for the O2 sensor heater circuit to burn out.........or send 12v back up to the ecu through either a sensor ground, signal return, or 5v reference line.

Fords are much more fun to diagnose than either chrysler or GM.

[CAP1]

Well.....I saw 60 in a two year period.

You have to remember that I was the sole technical support for products sold by standard motor products and Blue Streak and diagnosed hundreds of cars per week with problems that most technicians run into only 5 or 6 times in thier entire career.

I was usually brought these issues by our vendors (pep boys, auto zone, all the big chains) after the customer had purchased multiple ecus and still had the same issue.

Remember also that the reference voltage as sent to three wire sensors is divined by the same power supply that runs the entire ecu so that any grounding of said three wire sensor reference voltage is also making the voltage that runs the ecu short to ground.

Now a two wire sensor reference voltage power supply is designed to resist to ground and grounding of that type of sensor line will only result in the readings the ecu interprets to be maximum in one direction.

That said, I probably had many hundreds of 1996 jeep grand cherokees, 1996 dodge caravans, and 1996 dodge durangos during that same period.

1996 is a nightmare year for any dodge/jeep electrical diagnostician.

Fords issues were mainly with the dpfe sensor itself and o2 sensors shorting which causes the driver for the O2 sensor heater circuit to burn out.........or send 12v back up to the ecu through either a sensor ground, signal return, or 5v reference line.

Fords are much more fun to diagnose than either chrysler or GM.

 bolded.....THAT is the problem. no one at any of those chains should be allowed to do more than change a tire.

 so oc course you're gonna get this stuff from them. most have trouble figuring their way out of a wet paper bag with a knife.

[Shuffler]

bolded.....THAT is the problem. no one at any of those chains should be allowed to do more than change a tire.

 so oc course you're gonna get this stuff from them. most have trouble figuring their way out of a wet paper bag with a knife.

Which reminds me....

If you are ever stuck in a room with no doors or windows but you do have a mirror and table simply look into the mirror to see what you saw. Take the saw, cut the table in half. Stick the two halves together to make a whole and climb through it.

[KgB]

in my nearly 30 years, i've NEVER seen a DPFE sensor prevent a vehicle from starting. or the old style of egr position sensor either. i've replaced more than my share of them too.

Maybe he meant very popular FPDM?

[icepac]

The chains are where the ECU's and other sensors are purchased for places such as independants, dealerships, and electrical specialists.

I only supported a couple of pep boys mechanics because they are watched by management to not get in over thier heads and instead concentrate on the gravy.

Diagnosis does not pay unless you are an electrical specialist shop and have properly communicated with the customer what fixing his car may entail.

I charge $160 per labor hour.

[321BAR]

bolded.....THAT is the problem. no one at any of those chains should be allowed to do more than change a tire.

 so oc course you're gonna get this stuff from them. most have trouble figuring their way out of a wet paper bag with a knife.

just a week ago i had my brakes done at sears auto center because my mechanic doesnt work weekends... said brake job has now shattered and my mechanic has said that it looked like a grenade went off inside the drum brake housing...


just to show you never go to chains...

[CAP1]

just a week ago i had my brakes done at sears auto center because my mechanic doesnt work weekends... said brake job has now shattered and my mechanic has said that it looked like a grenade went off inside the drum brake housing...


just to show you never go to chains...

 that sounds almost as if a retaining spring was left off.

 pretty sad that they couldn't competently handle something as simple as a brake job.

the place i mentioned that i worked where i kept getting in trouble for my lack of verbal filtering.........i could tell ya some horror stories about the brake pads they used there. i had to friggin burnish them after each brake job. i ain't burnished a brake pad for 20 effing years, till i went there.

[icepac]

I still grind the proper arc into brake shoes.