'01 Sport 4.0L P0351 code and PATS issues

[godothunder]

2001 Explorer Sport 4.0L Vin E

Saturday June 27th, CEL comes on driving home from work

Sunday June 28th, Go to work in the morning and check the code (I work at O'Reilly's) with the scanner and it pulls code P0136 Oxygen Sensor Circuit Bank 1 Sensor 2 (see P2270, P2271). I tried to change the sensor but could not get the old one off. My plan was to spend more time on it Wednesday or Thursday on my days off.

Monday June 29th, On my way to work I noticed the CEL was not on anymore.

Tuesday June 30th, Still no CEL

Wednesday July 1, On my way to see my son the CEL all of a sudden starts flashing. No place to pull over, about 300 yards later at a stop light CEL goes off. Light turns green and CEL starts flashing almost immediately after hitting gas pedal. Pulled off the road down the street and shut everything off, jumped out and checked the cats, they were smoking but not glowing. Obviously the engine was also running very rough. Had the thing towed to a shop that I deal with at work but they were closed. Ran down to my store and grabbed the OBD scanner and pulled codes:

P0351 Ignition coil A primary/secondary circuit malfunction
P0301 Cylinder 1 misfire detected
P0305 Cylinder 5 misfire detected

Thursday July 2nd, Shop calls me and says I need a new coil pack, they read those 3 codes. (Duh, I left you a note in the drop box telling you that.) Still had to pay $70 for that.
I went to pick up the vehicle and drive it just down the street to work to change the coil pack. NO CEL on, and the thing ran fine. Put on a house brand coil pack and it ran like crap. Put on a BWD coil pack and it still ran like crap. I should also say that just last month I replaced the plugs with OEM Motorcraft plugs and put on BWD wires.
After testing all 3 coil packs with a multi-meter all 3 had the same exact readings. Original coil pack must be good, right? Reinstalled original coil pack. Spark still VERY weak on cylinders 1 and 5. Cleared codes many times and still comes back with P0351, but no misfire codes. Installed new Crank position sensor. Same results. Unplugged PCM and opened up, looks fine, pins look good, plug looks good. Slathered a bunch of dielectric grease on plug and plugged PCM back in. Same results.
I was pushing on the plug with the engine running and BAM! the thing runs like a champ. Wiggled it again and back to running like crap. Gave the plug a good smack and BAM! runs great again. Test drive around the parking lot and no problems at all and NO CEL on. Left it running for 5 mins while I went into the store, came back out, misfiring again and code P0351 is back. Bad wire in the harness from bank 1 and 5 on the coil pack? That's the only thing I can think of.

I never got a chance to test that theory because I had ordered a new PCM from work but it has to be flashed. Says so in the computer system and also the instructions in the box that it came in. Manager insists that I go swap it out anyway just to see what happens. I proved him wrong, put the thing in and not a damn thing happens. Later on in the day (after the rain quit) I put the old PCM back in and hook up the battery. Go to start the thing and absolutely nothing happens. I noticed that THEFT light is flashing. Let it stop flashing then watched what code it flashed at me 1:5. From what I've researched that means it's not recognizing my transponder key.
Made a call to a steering column shop we deal with at work and he said that I should have been able to put the original PCM back in and it should start right up. That obviously is not happening.

So 2 questions, do I need the old PCM re-flashed and the key re-programmed, or just the key re-programmed? I should point out too that I only have 1 key for it. That's all that came with it when I bought it 3 years ago.

2nd question, what the hell else can be causing the P0351 code?

And a bonus question, is there any way to reset the PATS system without scanner tools and computers? I read that if you leave the battery cables off for 2 days it will reset.

Sorry post is so long but I wanted to give as much info in first post as possible.

Any ideas?

Thanks

 

[2000StreetRod]

Bank 1 sensor 2

The bank 1 sensor 2 is a post cat sensor that helps the PCM determine the efficiency of the cat. P0136 may have been the PCMs first detection of misfire. The PCM computes the power pulse when each cylinder fires and compares that to the others. The Explorer has a waste spark ignition system with paired cylinders. When one cylinder fires on its compression stroke the paired cylinder fires on the exhaust stroke. The paired cylinders are shown below.

As you can see the reported misfiring 1 and 5 cylinders are paired. Since replacing the coilpack did not correct the misfires then you should check the primary and secondary circuits for cylinders 1 and 5. I don't have a wiring diagram for the 2001 Sport but on my 2000 Sport I think the primary trigger wire for cylinders 1 and 5 is the Tan/White wire from PCM pin 26. Sometimes the PCM pins get pushed back into the connector and don't make good contact. You should also check the secondary circuit for a bad spark plug, a broken or loose ignition wire.

I have three PATS keys that are recognized by the PCM but I only use one. On one occasion I had the power to the PCM disconnected for months and it had no problems recognizing the previously stored PATS key codes when power was applied. Removing power to the PCM clears the keep alive memory (KAM) that stores learned parameters such as fuel trims but does not clear or reset stored PATS key codes.

I doubt that you need the original PCM reprogrammed unless you shorted something when there was still power to the KAM. I agree that the replacement PCM must be reprogrammed with the correct strategy before it will work in your vehicle. Now that the original PCM no longer recognizes your only PATS key you might be safer to use the replacement PCM. That means programming the replacement PCM with the correct strategy and then programming to recognize your PATS key. You may be able to take just the PCMs to a dealer and get the replacement programmed like the original. Any PATS qualified locksmith or the dealer can program the PCM to recognize the PATS key but they'll need access to the vehicle. It won't be cheap.

 

[godothunder]

So last night at work I took the scanner out to the truck for ***** and grins and came back with B1601 - PATS Received Incorrect Key-Code From Ignition Key Transponder
and also B1342 - Defective ECU

So it looks like my only option is going to be finding someone that can come here and reprogram the key back into the PCM. Or have it towed again, which I really don't want to do.

 

[2000StreetRod]

poor connection?

As I recall B1342 can be generated when the PCM is unable to communicate with other devices in the vehicle. Did you check for bent or pushed back pins on the PCM connector? If the PCM connector is defective programming the replacement PCM won't solve your problem.

 

[godothunder]

Update

Had a locksmith come out yesterday and try to program the key but no matter what he did it kept saying "no key loaded". So I said hell with it and had it towed to a shop where they are going to either reflash the old computer or use the new one I have and just program that and the keys. When all this crap is said and done that damn misfire problem better have gone away.

 

[godothunder]

So the explorer is back home and running well so far. The shop said they had to flash the new computer 3 times before it would take. Makes no sense to either of us but at least it's running. Misfire seems to have gone away so hoping that it was the PCM itself causing the misfire. They guy only charged me $150 for flashing 3 times and making me a 2nd key so I'm kind of happy about that.