i have a 97 ford ranger with the 3.0 Vulcan single cab with 101 thousand miles on it original trucks and drives fine no exseissive fuel comsumtion I get 19-22 mpg it automatic I keep getting code p1401 Diff Pres feedback egr circuit high input I put in a brand new Dpfe Sensor I was told that would fix the problem it did not it came right back ive put a new camshaft synchronizer in new egr valve new egr pipe from exhaust to egr valve done a complete tune up cant find any vaccume leaks running out of things to try wondering what else I'm missing? also my egr valve is working fine when I put vaccume on it truck wants to die. Will it hurt to drive the truck like this I check it often to see if any new codes come on none have if I have a major computer or electrical problem I really don't want to get into all that with a truck that runs just fine why I'm asking if it would hurt it?

 

I answered this question on another forum for you earlier.

While you have done a fair amount of diagnostics and parts replacements, you have just hit the tip of the diagnostic iceberg.

If you follow the few suggestions mentioned in the other Forum, and still have no luck, yes you will be in for a possibly long diagnostic session.

If you want to dive into that one day you will need access to the Correct pin point test for your truck.

I posted some of this test to give an example of how extensive it is for my 2002 2.3 I am unsure how long this test is for your truck.

This would require a factory service manual or subscription to alldata.

But the problem is fixable and iIam 99 percent sure the cure would be inexpensive.

 

The OP didn't mention this, easy enough to check.

1997 FORD RANGER 3.0L V6 EGR Valve Control Solenoid / Motor | RockAuto

Mr. Outlaw
What other forum _ link. ?

Too bad the camshaft synchronizer was replaced, which has nothing to do with this problem.
Maybe it needed replacing anyway.

 

Yes, you can drive the truck as much as you want, it won't hurt anything.

DPFE sensor has 2 hoses that go to the exhaust system, one is closer to the EGR Valve than the other.
When the computer uses the EGR Solenoid(EVR) to send Vacuum to the EGR Valve the EGR valve will open and the Pressure in the nearest hose will drop lower than the other hose, this pressure difference is how the computer "knows" how much exhaust gas is flowing into the intake.
DPFE = differential pressure feedback

DPFE sensor hoses are different sizes, so there is an order, they are not reversible.

Check that both these hoses are clear, they have a tendency to collect water inside, and that is what usually "kills" DPFE sensors, moisture.
All exhaust has water vapor, a by-product of burning gasoline(H) with air(O) is H2O(water), which is why exhaust systems rust from the inside out and why water drips from the tail pipe.
When you shut the engine off the rubber hoses and DPFE sensor cool off faster than the metal exhaust system so water vapor condenses on the cooler surfaces, just like it does on the outside of a cold glass of beer on a warm day.

So clear the hoses, and make sure electric connector wires and contacts are clean and dry

EGR solenoid(EVR-electric vacuum regulator) is a 12volt solenoid, computer pulses the GROUND on this to apply a little or alot of vacuum to the EGR Valve.
So key on, one wire at solenoid will have 12volts, other wire runs to the computer.
You can apply 12volts and ground to this solenoid to see if it "clicks" open, even 9volt battery will work, there is no Polarity with connector removed, it is just a coil of wire inside.
Check hose on this as well, one goes to intake manifold, other goes to EGR Valve

 

i replaced the camshaft because I got a code for it when I replaced it it took the code off

 

code p1401 - Ford Ranger Forum

 

That thread goes on for a while _ it discusses so much, it's hard to keep track of what the OP has done to test the EGR/DPFE circuit.

This is the tutorial that I used when I did mine.

Part 1 -How to Test the Ford EGR Valve EGR Vacuum Solenoid, DPFE Sensor

I still had the metal DPFE sensor and it was internally corroded and shorted on the inside.
The circuit board was covered in rust and you could tell it was wet at one time.

I went through the whole system anyway looking for vacuum leaks and I also replaced the pressure hoses from the chimney, they were quite deteriorated.
I also removed the chimney itself and cleaned it out for good measure. (had to use oxy/acetylene to heat the nut up on the manifold to get it loose)

I had no code, but the truck would jerk along through town at 20 to 30 mph.
Not bad jerking, but small little misses _ very annoying.

At the time I knew nothing about fuel injection and what all the sensors were doing, so it was quite challenging for me.
The only code showing up was for the EVAP system when I first bought the truck.