What is this?

[Droptopfiveo]

What is the PCM in the EGR system and where is it located on my 94 ford explorer. I got a code of 558 which is EGR valve regulator solenoid circuit failure. I have replaced this part along with the PFE, and the EGR but still the same problem (hesitation). So the only thing left in the system is the PCM not sure what that stands for and where it's located. Oh yeah I also checked and replaced hoses in the system.

 

[elkhunter]

I would like someone to decipher all of those 3 letter things so I could have a hint at what I am looking for.

 

[Droptopfiveo]

EGR Exhaust Gas Return

PFE preasure feed back system

I don't know what the PCM is that's what I'm looking for and where it's located.

 

[4544x4]

PCM=Powertrain Control Modual
I check on the loc. thursday at work.

 

[RiverRat]

PCM powertrain control module. Engine computer. PCMs are tough. Don't go bad often.

 

[LessDirty]

I can help with this. FIrst I want you to find the vacumm line that goes to the EGR. Next I want you to disconnect the vacumm line and add you own.....long enuff for you to fit it up to your mouth.

Next, suck on the vacumm line that now connects to the EGR.....the engine should stumble and sometimes die. If this happens the EGR is good. If you suck hard and nothing happens, the EGR is bad. Either the diaphram is cut or dry rought or the plunger is caked with carbon and can't move.

Next, if the EGR is good, I want you to take a volt memter and read the pressure sensor. Are you getting 12 volts to it? If not you have a wire short. If so, does the voltage go up and down based upon RPM. You'll have to search for how many volts the sensor operates at at idle. Its prob at 1 volt and at 3000 rpm at 3 volts....or something like that.

We have seen many Fords that have a clogged exhaust tube that leads to the EGR. Sometimes it gets so filled with carbon that it can not get sufficeint exhaust flow, so you might want to take a look at it. To clean it out, I have removed it, used a carb cleaner and a rifle bore rod.

Good luck and lemme know if you have more questions!

 

[Droptopfiveo]

EGR is new where is the pressure sensor located. I'm looking it up in the book now but haven't found it yet. I'll also check the metal tub that goes to the EGR like you stated. I have also replace the Idle Air Control.


Is the presure senor the same as the fuel pressure regulator?

By the way here are the codes I'm getting.

KOEO 558

KOER 332 and 538

 

[MrShorty]

One note on the KOEO 558. That points to a fault in the EGR solenoid circuit. The EEC-IV system is not very sensitive to faults in this circuit. This circuit is just like the CANP solenoid circuit and the transmission solenoid circuit. Really only two faults that can trigger this code, Either that EGR solenoid circuit is open or it is shorted to ground. Get a wiring diagram and trace that circuit from the EEC relay to the PCM and find the break/short. That should resolve everything (I expect the KOER 332 is due to the fault in the EGR solenoid. If the computer can't cycle the solenoid, then the pressure sensor isn't going to "see" the solenoid open/close.).
EGR pressure sensor (there are various flavors depending on make/model/year) is not the same as fuel pressure regulator. EGR pressure sensor measures exhaust back pressure (when it's open to the exhaust, see notes on EGR solenoid), FPR is a backpressure regulator that controls fuel pressure at the fuel rail.
And, as one final note, the 538 indicates that you missed/ignored the "goose" test when requested during the KOER test.
And to answer your original question, PCM is located behind the kick panel, under the glove box, just in front of the passenger door.

 

[LessDirty]

Droptop, I can walk you thru it and or explain it better over the phone if you want. 281-726-1659. I can even fax you a print up on my ALLDATA.

My name is Lee.

 

[Droptopfiveo]

I did all the following except for trace the wires back to the PCM. I need to find the schematics to do this. Maybe they're in the hanes book.

 

[MrShorty]

Can't speak for the Haynes wiring diagrams. I've found the wiring diagrams in Chiltons are adequate for much of the EEC-IV wiring. The Chiltons wiring diagrams can be had in the vehicle repair guides at www.autozone.com

 

[Jason94sport]

I had an EGR problem when I first got my truck. I replaced the metal rectangle thing that the 2 little hoses come out of on the drivers side intake. Not sure what it was called, it had a plug going into it also.

 

[LessDirty]

Jason.....THATS IT! Thats the part that goes bad in 99% of the cases. Its about the size and shape of a deck of playing cards with 2 vacumm line running to it with a 2 pin pig tail.

Thats the issue with this guy.........I am almost 100% positive. Its not just the Exploder either, Windstars, Taurus, and so on.

 

[Droptopfiveo]

Yeah I replaced that part already.

 

[Con Seann3ry]

well...i may or may not have had the same problem as you...but I replaced the same stuff and while i still don't have the code completely gone, it only comes on once like evry hour for a couple seconds...which is good enough for me. I'm sorry I don't have a pic of the thing i'm talking about, but if you look at this picture

it would be out of the picture to the top right - there is an electrical connection going onto the back of it, and you can take it out with a wrench...I took out that thing, and it was caked in weird crap, so I sprayed this little red thing at the end of it with Gumount Carb Cleaner (sensor safe) and used some q-tips to get it looking good, when i put it back in my CEL was mostly fixed....if anyone knows what part i'm talking about please let me know too

 

[LessDirty]

aaauuuhhhhh........no. That picture reminded me of my focus after I have had too much to drink.

Which is prob why my head starts to hurt!

 

[Droptopfiveo]

I think you may be talking about the EGR vacume solenoid or the PFE (presure feedback sensor. If so both of them have been replace and all the connections have been checked.

 

[Con Seann3ry]

nah, it's this thing that's sorta like a spark plug...i replaced the EGR solenoid and the DPFE (mine had a dpfe for a 94, yours should too) and there was this little thing with a red weiner, cep tmine was all black, so i cleaned that up, and t was good to go again, and i', durnk.

 

[LessDirty]

ROFL! exactly....