Issues after PCM replacement

[Jayme]

Hey fellow car enthusiasts,

I'm writing here to share my frustrating experience with my 2010 Ford Explorer. For the past few months, I've been dealing with a troublesome check engine light that just wouldn't go away. It has been an ordeal, and I'm seeking some advice or recommendations from this community.

After trying various solutions, including replacing sensors and diagnosing the issue extensively, the dealer identified a "corrosive connection" between the PCM and wiring harness. To address the problem, I decided to go ahead and replace both, which ended up being a significant expense.

At first, everything seemed fine, and I had a smooth driving experience for two weeks. However, out of nowhere, my Explorer started experiencing a rough idle, with the check engine light flashing at times. The smell of unburnt fuel added to my worries.

Back to the dealer I went, and the past few weeks have been a back-and-forth saga of resetting the engine light, reprogramming the PCM, and even replacing a fuel injector (which cost me even more money). Unfortunately, none of these attempts have resolved the issue, and the problem persists.

I strongly believe that the PCM is faulty and is the root cause of these problems. Despite the dealer acknowledging the warranty, they seem reluctant to admit that the PCM might be at fault. I'm getting frustrated, both with the recurring issues and the mounting expenses.

Now, I'm seeking advice from the community. Has anyone encountered a similar issue with a newer computer in an older vehicle? Is changing out PCMs a common practice, and can it cause complications like these?

At this point, I don't want to pour any more money into my beloved Explorer. It has served me well for over 7 years without any significant issues until now. If the dealer insists on charging me more to fix the problem without a guaranteed solution, I might consider parting ways with it and have it scrapped for parts.

Any insights, suggestions, or experiences would be greatly appreciated. Thanks for your time and assistance.

 

[ThunderbirdSport]

When you say dealer...do you mean a Ford dealership?

I'd take it to a different shop. Hell, get you a code scanner (not a cheap 20 dollar from wal mart) and scan codes yourself and save the diagnostic fee from a shop.

You have a 13 year old rig....a scan tool ought to be in your inventory

It's possible the PCM might be bad, but in my experience a bad one = no start, or at least runs so bad that the vehicle is nigh undrivable.

First off, I'd check the fuel pressure. I honestly don't know if these things have a regulator, but aside from that I'd check the charcoal canister, since you said you smell raw gas.

Physically changing the PCM itself is straighforward. There's likely some "calibrating" of various electronics afterwards...on these, I don't know. Most of my experience with changing PCMs and EECs relate to older 5.0/5.8 (Windsor) vehicles...

What engine does yours have?

 

[94Eddie]

It would help to know what engine is in your Explorer and very helpful to know what codes are being tripped. Otherwise, we are just guessing as to what is causing the problem.

 

[Jayme]

Engine: 4.0L V6 FI GAS VIN E SOHC

Codes that originally started this whole thing(after new PCM installed):
P0201, P0300, P0301, P0302, P0303, P0316, P1260, P2196

Thats what the local Ford Dealer records show.

They did some resets and claimed to reprogram the new PCM. Then on the drive home, it started showing the same symptoms. Did a U-turn and took it right back.
New code found was P0201. That's when they replaced the single fuel injector.
Picked it up and yet again the very same symptoms quickly appeared. (They claimed to do test drives, but who knows.)

So that's where I am at now. It's currently at the dealer with an engine light and I'm waiting to hear back.

I can't do anywhere else, correct? Since the local Ford Dealership is the only place that can program/reprogramme PCMs?

 

[94Eddie]

IMO, you need to find a really good automotive diagnostician in your area. It is obvious that the Ford technicians don't know what the hell they are doing and this isn't all that unusual. Their strategy is to just throw parts at the problem, charge you for it and hope there is a chance one of them works. My guess is that all the work they have done is irrelevant to solving the actual problem.

 

[Jayme]

Where or what do I even search for when trying to find a local automotive diagnostician? I was led to believe that the local Ford Dealership only has the tools to program the PCM.

 

[J_C]

Hey fellow car enthusiasts,

I'm writing here to share my frustrating experience with my 2010 Ford Explorer. For the past few months, I've been dealing with a troublesome check engine light that just wouldn't go away. It has been an ordeal, and I'm seeking some advice or recommendations from this community.

You need the trouble codes. I suggest an inexpensive option which is a ELM327 based dongle and Forscan app for android, apple, or windows devices... whichever you want to use.

After trying various solutions, including replacing sensors and diagnosing the issue extensively, the dealer identified a "corrosive connection" between the PCM and wiring harness. To address the problem, I decided to go ahead and replace both, which ended up being a significant expense.

Do you still have the old PCM? Was the replacement new, used, or remanufactured? Always ask for the old parts back. Depending on the nature and extent of the corrosion, you may not have needed a new PCM or harness. How did they replace the harness, the entire thing or graft on the connector and pigtail (wires a few inches)?

At first, everything seemed fine, and I had a smooth driving experience for two weeks. However, out of nowhere, my Explorer started experiencing a rough idle, with the check engine light flashing at times. The smell of unburnt fuel added to my worries.

This makes me suspect that the initial diagnosis was wrong, or the harness has some problem, or past the part they replaced, has frayed or is shorting out. The trouble codes are going to be a hint where to look next.

Where do you smell the fuel, in the engine bay, out the exhaust pipe, or elsewhere?

Back to the dealer I went, and the past few weeks have been a back-and-forth saga of resetting the engine light, reprogramming the PCM, and even replacing a fuel injector (which cost me even more money). Unfortunately, none of these attempts have resolved the issue, and the problem persists.

So at that point, the shop suspected a misfire. I wonder what their evidence was, but would pursue this possibility. Along with the trouble code(s), I'd use a scan tool capable of live data and look at long term fuel trims among other things to see if anything is out of bounds. Of course it may need to be running poorly to catch the problem but you don't want to run it too long if it's putting unburnt fuel through the cats as that can damage them.

I strongly believe that the PCM is faulty and is the root cause of these problems. Despite the dealer acknowledging the warranty, they seem reluctant to admit that the PCM might be at fault. I'm getting frustrated, both with the recurring issues and the mounting expenses.

This would be a good time to try plugging the old PCM back in, cleaning corrosion off the contact if that's the problem, even soldering a replacement pin on the PCB for that contact if necessary, or if all else fails, a jumper wire from that pin's location on the PCB, to the corresponding harness wire. With it working fine for a couple weeks, it is not likely to need reprogramming. I mean it may need programmed the first time and apparently it was (or was already compatible) to work for two weeks.

Now, I'm seeking advice from the community. Has anyone encountered a similar issue with a newer computer in an older vehicle? Is changing out PCMs a common practice, and can it cause complications like these?

No changing out a PCM isn't all that common, it happens but (IMO) more often than not, a shop just wants to do that when they can't find the fault. I suppose it's possible that if you had one bank misfiring due to the fuel injector wire shorting out to ground, then that fried the transistor in the original PCM that switches the injector on, then if the short remained, could do same damage to replacement PCM. This is just a possibility/guess, not enough info to leap to this being the situation. You can check for this by using a multimeter to measure for the injector voltage blips while idling and compare to another injector, but first the evidence to bother would be having a cylinder misfire trouble code, and/or, engine running the same with and without that injector plugged in.

At this point, I don't want to pour any more money into my beloved Explorer. It has served me well for over 7 years without any significant issues until now. If the dealer insists on charging me more to fix the problem without a guaranteed solution, I might consider parting ways with it and have it scrapped for parts.

Any insights, suggestions, or experiences would be greatly appreciated. Thanks for your time and assistance.

If that shop can't fix the problem then you need a different shop. If you (or the shop does) have your old PCM, I'd clean the contact as mentioned previously, install it, and return the new PCM to the shop and insist on a refund for the part even if the labor isn't refunded.

Some other specialty shops can flash PCMs but you may need to call around to find one, ask the if they know of a shop that does. There may also be online services that can do it or test either of the PCMs, even pull the firmware off the old and flash to the new one.

To find a better shop, I'd prepare a concise summary of what has happened so far and call a few, but first, pull the trouble codes or at least ask the shop what codes they pulled. Hopefully they made notes.

 

[94Eddie]

Where or what do I even search for when trying to find a local automotive diagnostician? I was led to believe that the local Ford Dealership only has the tools to program the PCM.

I don't believe the Ford dealer knows how to diagnose the problem. It seems to me they are just throwing parts at the problem hoping one will work. They are the most logical one to program the PCM but if they have done this and the problem(s) still exist then programming isn't the issue unless they programmed it incorrectly. I live in the Mid Atlantic area so I don't know anyone in your area. Maybe someone here that lives near you can make a recommendation. I

 

[ThunderbirdSport]

Yes, I agree with the above posts. Hunt around and either find a good shop with a regard for diagnostics, or get a decent scan tool and do it yourself.

I'd go get your ride back, it's plain as piss in a pop bottle they are clueless and shouldn't be allowed to touch cars.

Forgive my bluntness, but some f'n people shouldn't be working on cars for a living and it seems as if you've discovered some of those kinds...good luck, keep us updated.

 

[Jayme]

Thanks for the valuable feedback.

I just got an update from the dealership. This time they are claiming:

CUSTOMER STATES CHECK ENGINE LIGHT IS ON. SCAN COMPUTER CONTROL SYSTEM WITH IDS SCAN TOOL. FOUND CODE P0201 INJECTOR #1 CIRCUIT REMOVE #1 SPARK PLUG FOUND COOLANT IN THE #1 CYLINDER. THERE A COOLANT LEAK COMING FROM THE THERMOSTAT HOUSING CAUSING THE THE ENGINE TO OVER HEAT. WHICH CAUSE THE ENGINE TO BLOW A HEAD GASKET. THERE WHITE SMOKE COMING FROM THE TAIL PIPE AND WATER UNDER HEAVY ACCELERATION. THE ENGINE RUN ROUGH ONCE THE VEHCILE GET HOT. RECOMMEND REPLACE HEAD GASKET AND THERMOSTAT HOUSING.

Not going through with it as they said it's a "big job" meaning a big expense. I am not very confident. As another has said here, they seem to be throwing stuff at it hoping something will fix it. I've already spent way too much for a 13-year-old vehicle.

@J_C If you find my above reply, I list the codes they found.

 

[Metalface]

Whoa whoa. Did they tell you *why* the connection corroded? Let's start there.. Maybe something is wrong with your wiring in other places or the battery itself. Or who knows. What spot on the harness was corroded?

Now they're saying head gasket.. I could see that being possible. Edit: (I mean.. Duh -- if there REALLY is coolant in the cylinder,) Do you have info on maintenance records from Previous Owner(s?) I hope they never put stop-leak or head gasket stop-leak in it.

Maybe steam got to the wiring harness? I'm scratching my head at this. I'm frustrated that this is happening to you... I'd be pissed if this were my truck.

 

[94Eddie]

Thanks for the valuable feedback.

I just got an update from the dealership. This time they are claiming:



Not going through with it as they said it's a "big job" meaning a big expense. I am not very confident. As another has said here, they seem to be throwing stuff at it hoping something will fix it. I've already spent way too much for a 13-year-old vehicle.

@J_C If you find my above reply, I list the codes they found.

If there is a blown head gasket then this is something they should have found in the beginning. They are either incompetent, dishonest or maybe both to have done all the irrelevant things they did BEFORE finding the head gasket problem.

 

[Metalface]

If there is a blown head gasket then this is something they should have found in the beginning. They are either incompetent, dishonest or maybe both to have done all the irrelevant things they did BEFORE finding the head gasket problem.

He's right, you know.
I'd go somewhere else... But have them release all of their info they gathered to you and what they "did or didn't do" and let the new place make sure they "did or didn't" do what they said they did, or didn't. If you feel me.

Did YOU notice symptoms of a blown head gasket before you brought it in? Anything out of the ordinary?

 

[J_C]

Thanks for the valuable feedback.

I just got an update from the dealership. This time they are claiming:



Not going through with it as they said it's a "big job" meaning a big expense. I am not very confident. As another has said here, they seem to be throwing stuff at it hoping something will fix it. I've already spent way too much for a 13-year-old vehicle.

@J_C If you find my above reply, I list the codes they found.

As others stated, something is wrong with this shop.

If you can get your old PCM back and a refund for the new one, I'd do that, confirm yourself whether there is coolant in cyl #1, and decide from there whether to take to another shop.

As far as the trouble codes go, I was wondering what they were before the PCM was replaced. Once the check engine light was set, it really needed to be determined what was causing that, not continuing to drive it till you know the extent of the problem. Definitely checking coolant and oil levels should be done. Did the temp gauge not indicate overheating?

Unless the undercarriage is rusted out, I'd think it is worth having a different shop do the head gasket job, though it's probably about a $2K cost in your area, and could rise higher if the head is warped. I'd be contrasting that with what $2K plus current vehicle scrap value is worth, what could I replace it with for $2K5? How many miles on the engine?