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EGR or PFE? '94 Explorer 4.0 2wd

martinh67

Member
Joined
December 10, 2008
Messages
18
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City, State
Virginia
Year, Model & Trim Level
'94 XLT
Newbie here.

SYMPTOMS
1. Little rough on the idle - sometimes it sways back and forth. At normal driving speed, she purrs like a kitten.
2. CEL comes on after it starts warming up

TROUBLESHOOTING
1. Code 332 KOEO test (EGR Valve opening not detected)
2. Code 335 KOEO test (PFE or DPFE sensor voltage out of Self-Test range)
3. Code 543 KOEO test (When the PCM commanded the fuel pump on, voltage was not detected on FPM) Related?
4. Code 326 KOER test (PFE or DPFE circuit voltage lower than expected with zero EVR duty cycle)

Is it the EGR valve or the PFE? Or both??
 



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Almost certainly PFE. I've had the 335 code when I had a bad DPFE.
 






KOEO codes have to be electrical in nature, so KOEO EGR codes almost never point to the EGR valve itself. Check the PFE sensor circuit.

KOEO 543 is likely unrelated to the PFE codes. Where it runs, the fuel pump must be working. Check the fuel pump wiring, just in case there's a loose connection that is waiting to leave you stranded.
 






check DPFE sensor, those are prone to go bad in fords.
 






Thanks fellas

I'll go get one AZ or Adv Auto
 






Replaced PFE and after making sure all vacuum lines are connected, CEL went out, however still a little rough on idle. I will go ahead of all the recommended cleaning of the IAC and MAF.

I also found the rubber ends of each vacuum lines to be very loose. Seemed they expanded. Replaced all the ends on the vacuum tree and found an open w/o and end.
 






Prior to cleaning the IAC and MAF, The X was running great w/o any roughness. SO I went ahead and inspected the IAC and found some dirt in it. I cleaned it and attached it. Then I went and inspected the MAF, it was clean as a whistle. Then I notice the air filter assembly box was a little open. Fixed that and everything is fine for now.

Gas milage greatly improved based on the miles I driven since last fill-up. I'll find the exact milage on my next trip to the gas station.
 






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