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2001 Explorer 5.0 P0174 Code

Had a Triton 5.4 do this. Ran great open loop, went to hell once it warmed up and went closed loop. Threw bank 2 lean codes.

Chased all sorts of things. Threw plugs and coils at it.

Ended up junking it due to rot and other gremlins, but I always suspected that a rotting exhaust manifold on that bank was letting air into the exhaust stream, and throwing the oxygen sensor off. You got any exhaust leaks upstream from the O2 on that side?
 



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This is a continuation of the P0174 thread... ( 2001 Explorer 5.0 P0174 Code ) Misfires on cylinders 3 and 5 (opposite sides of engine, same coil pack) and ignition coil B pri/sec circuit (If the 'primary' coil is #1 on the passenger (right) side, Coil B should be the driver side, so, same coil). I've tested with a HEI spark tester, no spark on 3 and 5 at the coil. 2nd set of coils (CarQuest Premium FWIW). I think I need to determine if the signal to the coil is present, but I can't find a break out of the coil connection as to which connector does what.

So far I've replaced the fuel injectors and connectors, intake manifold gaskets, MAF Sensor, Crankshaft Position Sensor, Throttle Pos. Sensor, EGR Valve and solenoid, PCV valve and grommet, and the PCM. I don't think it's the coils as they are new, the CKS could have been a bad source to the computer - replaced that. All that is left is the wiring harness? Or the PCM is bad (which I doubt as it is new)? The P0352 code was detected after the new PCM went in.

With the affected cylinders on opposite sides, that should rule out the O2 sens and possible exhaust manifold leak. Thanks again for your help.
 






I've merged your threads, as the same problem persists. It'll help avoid redundancy,

You did not mention new spark plugs. If they are new, still could be bad. Use autolite or motoraft plugs.

352 is cylinder b which is 2
 






Thanks for the merge, considered going with the original, but the P0174 code has cleared. At any rate, new Motorcraft AGSF32FM went in at 227,600 mi., or about 23K mi. ago. I'm headed to the part store for a test light - no spark at the coil, need to figure out why.
 












Have you taken the wasted spark coil off and look at the bottom of it? Look for a split. I went through seven coils trying to find what was making them burn up. I ended up parking the 1997 Mountaineer 5.0. That is the favorite of the six Explorers that we own or have owned.
 






Both coils only have an hour or two of running time on them. I'm going to test the coil, and try to test for the switching signal from the PCM. This has been our favorite vehicle as well, I'd hate to have it fall prey to some kind of gremlin.
 












Leading Causes Of Ignition Coil Failures​



Hmmmmmm..... :shifty:
 






@Exploder321 I don't know if this will help at all but this is what I went through before I punted. I hated to put the '97 MM 5.0 in the "penalty box" but it was costing me too much time, money and headaches. Now it has me part time consumed working to make it coil-near-plug with 1999 Crown Victoria parts.Link to original problem with the '97 5.0
 






allmyEXes, 6 pages on that thread, yikes! I'll look into that coil driver problem. I'm going to try my best to validate the signals and voltages going to the coil. Also going to replace the camshaft position sensor (a culprit in the diagnostic equipment article four posts up). There have been several failures identified since starting this thread, maybe I'll get lucky and find the coil killer!
 






A few new clues - the Motorcraft copper plugs (made in china) are at their 20k mi. expected lifespan - being replaced with Bosch Double Platinum plugs (the plugs are stamped GERMANY, though the box says made in rusha). When all this mayhem started, fist thing I did was install new plug wires (CarQuest Premium - made in china:( ). As it turns out, their resistance is about 4K ohms/ft, half of the 8k ohms/ft if seen specified for plug wires. I have a set of Walker 'ThunderCore' wires (MADE IN USA!! :D) that ohm out to the 8k value. The crap wires may be a culprit in the coil problems. The MC plugs have been testing out OK, ~ 6k ohms through the center and no leaks (cyl 5 and 6 so far).

The Walker wires click on to the plugs very nicely, the CarQuest wires don't. one of the CarQuest plug connectors pulled right out of the boot when changing it out a few weeks ago. I'm thinking many problems are result of junk parts from suppliers. :rolleyes:
 






Motorcraft SP432 plugs.

Motorcraft wires.

End of story.
 






With new plugs, wires, all verified with an ohm meter, ignition coil B still has a problem, P0352. The secondary codes seemed to have cleared, though I didn't drive it. It also threw a P1409 EGR vacuum regulator circuit code, I already replaced that. I want to check harness wiring continuity, but I can't find a wiring harness diagram with pin-out for an '01 5.0. The Haynes manual I have for '96 - '01 only has the wiring diagram up through '99, would that be the same?

If there is a trusted online source for purchasing a soft copy Ford shop manual that would be great. The ones I find seem sketchy.

Update - found the Ford Workshop Manual DVD on Ebay... will go from there. Will post if/when the problem has been isolated.
 






When the engine is warm at night in the dark mist some water over it with a spray bottle look for little sparks in arcs
Works for me every time In the case of bad spark plug wires
 






When the engine is warm at night in the dark mist some water over it with a spray bottle look for little sparks in arcs
Works for me every time In the case of bad spark plug wires
That's worked for me before, the spray mist is a new twist though. The wires are fresh out of the box, certainly something to consider since I found a dead wire in the set. Who knows these days as to quality.
 






Cheap wires not worth the box they come in and wires are only as good as the install! Must be routed properly and seated well

Seems like everytime I come into this thread there is a new code! We also have two threads going for this truck!
 






Back to this thread... 410Fortune, only 1 code right now P0352. I considered the break out box a separate question, sorry if that was a foul. (This a break out box would come in handy, if it existed). J_C, this is where we left the other thread, testing the wires!

So... following the testing procedure I pulled from the Workshop Manual CD, tested the Start/Run circuit RD/LG) at the connector for the problem coil pack (coils 1 & 2 - 2 specifically as it goes to cylinders 3 and 5 which is consistent with previous indications), that gave me 11v. Removed the fuel pump relay, then tested the #2 coil driver (RD/LB) with a test light connected between it and the Start/Run circuit - turn over the engine, NO DICE! To verify I was doing it right, I connected Start/Run to the #1 coil driver (DB/LG) and the test light lit up, blinking regularly as the engine turned over, a good indication.

Here's where I'm stuck - next test is wire continuity/resistance from the PCM connector to the coil pack connector. Pin 52 to the RD/LB wire at the connector, no connectivity (which was expected); but then checking the other coil driver wire, Pin 26 to (DB/LG) at the connector, and can't get a reading either. Somehow I'm not probing the PCM connector correctly - I'm using a safety pin which is close to the connector pin size, though no luck. Getting dark and rain rolling, will try this again tomorrow. Any recommendations on probing the PCM connector would be greatly appreciated.
 



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Upon closer inspection of the back of the PCM Connector, the pins are inverted from the diagram posted by J_C (attached here) - the convention being that the technician would twist and invert the connector so as to face the front of the vehicle to have the same orientation as the diagram, the left and right sides of the connector back are marked as follows:
79......................104
53........................78
27.........................52
1 ......................... 26

The mystery of the failed continuity checks is solved, it seems I was trying to ring out pin 78 instead of 52. Now to check the correct wires...
 

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