2.5L ('98-'01) P0401 & P1401 insanity

[blueberryranger]

Ive been researching here, other sites, chatgpt everything I can think of and i cant figure this out.

1999 Ranger 2.5L 126k miles , besides the check engine light i get this bogg of the engine when shifting into drive and starting off almost everytime. this is everything I did in order of circumstances to where I am now currently.

check engine light got a p0401 then proceeded to :

- new IAC valve - still same code
-new upstream o2 Sensor - nothing
-new DPFE sensor - nothing
- new EGR Valve - nothing
-new EGR pipe - nothing
- Hired a mechanic to come take apart and clean the enitre throttle body and intake manifold ( it wasn't clogged at all like ive seen in some cases ) - still got the same light 25 ish miles later after clearing code
- new evr solenoid - after this clearing of the check engine my p0401 went away and just got p1401 now.
- new hoses for the DPFE sensor ( theyre on the correct ports 100% sure ) - nothing
- bought a multimeter to check the wires that plug into the egr valve and they all checked out proper voltages aand after driving im getting both codes not stored after clearing them.

now this is where I am lost idk what else to do /try. I really appreciate some insight.

 

[franklin2]

Have you modified the exhaust or gutted the cat?

 

[blueberryranger]

Have you modified the exhaust or gutted the cat?

No nothing at all, bone stock. Passed smog last year in California.

 

[franklin2]

Looks like your last code is about the DPFE sensor. I would be curious, when the truck is warmed up and idling, if you found a port somewhere with vacuum on it, if you hooked the EGR valve vacuum line directly to the manifold vacuum port, does the engine stall? It should. That would verify the EGR valve is working, the EGR pipes are not clogged.

If it did not stall, that does verify the problem, you are not getting EGR into the intake. You will have to keep trying to figure out why. The exhaust going into the engine at idle should make the engine stall out.

If it does stall, I would check the wiring to the DPFE sensor. I would then unplug the sensor, run the engine, see if you get a different code with the sensor unplugged.