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DTC code P0354

Christang.GT

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I was driving my FBO tuned 5.0 and hit the gas like we always do. Then it started running wonky and my check engine light came on. I plugged my SCT device in and got these codes. The one I am mainly worried about is P0354 because I have no idea what that is. The other two I am certain is a bad spark plug or coil (which is throwing the startup misfire code) which I am already going to replace. Can someone help me? Anyone know what this could be?
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Cobra Jet

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For your P0354 - Check to make sure the coil pack connectors are not loose or damaged - do wiggle test. Also check the harnesses for them and make sure there’s no breakage.

After doing the above, clear the DTC code and see if it comes back.
 
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Christang.GT

Christang.GT

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For your P0354 - Check to make sure the coil pack connectors are not loose or damaged - do wiggle test. Also check the harnesses for them and make sure there’s no breakage.

After doing the above, clear the DTC code and see if it comes back.
Thank will do. But do you kno
For your P0354 - Check to make sure the coil pack connectors are not loose or damaged - do wiggle test. Also check the harnesses for them and make sure there’s no breakage.

After doing the above, clear the DTC code and see if it comes back.
By any chance do you know what cylinder corresponds to D?
 
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Christang.GT

Christang.GT

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So I pulled the coil pack and this was cylinder 1........ furthermore I put all new coil packs and still the same codes and the new coil for cylinder 1 is melted again! I’m afraid this is bigger then initially thought.
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El_Coyote

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having this same issue with my 2015 gt, tuned by unleashed performance. ran fine for years, today i found that one of my my msd coils was serious melted, worse than the photo above, swapped all stock coils back in, and the same cylinder on the passenger side closest to grille was extremely hot after running for like 30 seconds. Im wondering if the spark plug caused the coil to fail by not completing the circuit, i did put antiseeze on the spark plugs when installed, and the threads did look all gummed up when the plug game out.

Did you happen to ever find out what caused the codes and the coil to burn up
?
 

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Christang.GT

Christang.GT

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having this same issue with my 2015 gt, tuned by unleashed performance. ran fine for years, today i found that one of my my msd coils was serious melted, worse than the photo above, swapped all stock coils back in, and the same cylinder on the passenger side closest to grille was extremely hot after running for like 30 seconds. Im wondering if the spark plug caused the coil to fail by not completing the circuit, i did put antiseeze on the spark plugs when installed, and the threads did look all gummed up when the plug game out.

Did you happen to ever find out what caused the codes and the coil to burn up
?
Yeah that’s exactly what happened to mine, it ended up being my actual pcm being fried and sending a constant fire to whatever cylinder. I had to buy a used pcm from eBay, take it to my local Ford and they reprogrammed it to my car with both keys and then I got in touch with my tuner and re uploaded the tune after he had updated it to the new pcm. Hope this helps!
 

El_Coyote

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Yeah that’s exactly what happened to mine, it ended up being my actual pcm being fried and sending a constant fire to whatever cylinder. I had to buy a used pcm from eBay, take it to my local Ford and they reprogrammed it to my car with both keys and then I got in touch with my tuner and re uploaded the tune after he had updated it to the new pcm. Hope this helps!

thanks man that helps alot, any steps you took to pinpoint the pcm for sure? Im going to shop around for a replacement unit, maybe i can check the coil connector or something to see if its on all the time. just want to verify the issue. But your symptoms and mine are exact, so more than likely its replacement pcm time.

did you have to have the car there with the pcm, or did you remove it and bring in just the keys and pcm. my car is running bad, Idk if I want to risk driving it, the local dealership is about 5 miles away so it isnt terrible either just not the best situation.
 
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Christang.GT

Christang.GT

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thanks man that helps alot, any steps you took to pinpoint the pcm for sure? Im going to shop around for a replacement unit, maybe i can check the coil connector or something to see if its on all the time. just want to verify the issue. But your symptoms and mine are exact, so more than likely its replacement pcm time.

did you have to have the car there with the pcm, or did you remove it and bring in just the keys and pcm. my car is running bad, Idk if I want to risk driving it, the local dealership is about 5 miles away so it isnt terrible either just not the best situation.
Yeah I just checked the wires to the coils and the ones for the cylinder that was melted was always firing, then driving it I just unplugged the coil pack and injector for that cylinder and ran it as a 7 cylinder to the shop because I had to take the car and the pcm there, if you prefer you could tow it but running it without that cylinder firing and it did okay and it’s been fixed for ages now with no other issues so that’s good news
 

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@Christang.GT

Glad the coil tip helped and you were able to find the issue to resolve the problem.

Was there any explanations for the PCM prematurely failing? Did you open the original PCM to check out internals?

How did you determine it was the PCM - did you have data logs?

I’m wondering if the PCM failed due to water intrusion? As that would be the only single cause of such premature PCM failure (aside from circuit board solder trace failures/damages or attached hardware component failures on the circuit board).

Out of curiosity, was your PCM covered by a warranty replacement? I’m asking because I think the PCM falls under the 5/60 Powertrain Warranty (if it has not been tampered with via software tuning mods or actual physical damages).

If it was not covered under Powertrain warranty, what is approx total out of pocket expense for future readers who have the same issue?
 
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Christang.GT

Christang.GT

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@Christang.GT

Glad the coil tip helped and you were able to find the issue to resolve the problem.

Was there any explanations for the PCM prematurely failing? Did you open the original PCM to check out internals?

How did you determine it was the PCM - did you have data logs?

I’m wondering if the PCM failed due to water intrusion? As that would be the only single cause of such premature PCM failure (aside from circuit board solder trace failures/damages or attached hardware component failures on the circuit board).

Out of curiosity, was your PCM covered by a warranty replacement? I’m asking because I think the PCM falls under the 5/60 Powertrain Warranty (if it has not been tampered with via software tuning mods or actual physical damages).

If it was not covered under Powertrain warranty, what is approx total out of pocket expense for future readers who have the same issue?
Yeah so the PCM was found to have moisture in it, I don’t know from what or where or even how? But that’s what the dealer said. Then warranty did not cover it because I am far out of it as my car had 112k miles at the time. As for pricing I took a used PCM from eBay that I got and I got them to reprogram it to my car so just for the labor and reprogramming it was roughly $400 and some change. They had it done in a day and didn’t want to touch it more because with the mods I had on it at the time they said the car ran wonky. When I arrived to pick it up I just contacted my tuner (VMP) sent a picture of the ECU SWPN number and he sent me an updated tune to that new PCM, I flashed it on and the car fired up perfectly on all eight cylinders and has been running strong ever since as if nothing had happened
 

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Yeah so the PCM was found to have moisture in it, I don’t know from what or where or even how? But that’s what the dealer said. Then warranty did not cover it because I am far out of it as my car had 112k miles at the time. As for pricing I took a used PCM from eBay that I got and I got them to reprogram it to my car so just for the labor and reprogramming it was roughly $400 and some change. They had it done in a day and didn’t want to touch it more because with the mods I had on it at the time they said the car ran wonky. When I arrived to pick it up I just contacted my tuner (VMP) sent a picture of the ECU SWPN number and he sent me an updated tune to that new PCM, I flashed it on and the car fired up perfectly on all eight cylinders and has been running strong ever since as if nothing had happened
Great info!

Keep an eye on the PCM and it’s location; check for any water intrusion in the area immediately above the PCM, around or near it and/or the main harness going to it. If there was water intrusion the first time, it won’t be the last.
 

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so aside from other things i had to take care of, i got a price from the local dealer on the pcm and labor for flash. Wanted to make sure that the pcm is bad and not something else.

I disconnected the injector and the coil on the suspect cylinder, and removed the coil and tried to bench test it with a ground wire to it. no spark, just alot of heat in coil. popped the cylinder next to it off and hooked a coil to it and stead. with a spark plug on the end of the coil ofcourse and got a spark. flopped back no spark. so def got an issue with the connection, and the good thing is all my oe coils are still good.

How do I check the connection, when i bridge the two wires with a volt meter, it just hops around from 14v to 6v. i dont want to do much past that because i dont want to damage anything. all I know is that when the connector is plugged to the coil it just gets hot and fast, and produces no spark.

but the same coil placed on a known good cylinder produces a spark.
 
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Christang.GT

Christang.GT

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so aside from other things i had to take care of, i got a price from the local dealer on the pcm and labor for flash. Wanted to make sure that the pcm is bad and not something else.

I disconnected the injector and the coil on the suspect cylinder, and removed the coil and tried to bench test it with a ground wire to it. no spark, just alot of heat in coil. popped the cylinder next to it off and hooked a coil to it and stead. with a spark plug on the end of the coil ofcourse and got a spark. flopped back no spark. so def got an issue with the connection, and the good thing is all my oe coils are still good.

How do I check the connection, when i bridge the two wires with a volt meter, it just hops around from 14v to 6v. i dont want to do much past that because i dont want to damage anything. all I know is that when the connector is plugged to the coil it just gets hot and fast, and produces no spark.

but the same coil placed on a known good cylinder produces a spark.
That I wouldn’t know how to tell you, I did the simple swapping of coils and spark plugs and it always was an issue with the specific cylinder but then after that I just took it to my local Ford, I’m lucky to have a connect there that told me that’s what the issue was then I got my used pcm and let them handle it. I felt this was one thing I would let them hustle me for, but ultimately well worth it.
 

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Just diagnosed this issue on my fbo E-85 2015 Gt.
These engine run on two wire coils, the one constant wire found between all 8 coils is the violet wire which gets a constant 12v with the ignition on. while the the other wire is a different color on each coil, these wires go to the pcm. The pcm sends a ground signal through the different coloured wires based on the crank position sensor, completing the circuit momentarily, giving spark. This should not be grounded with the engine not running and if grounded, indicates either a short to ground in the harness or internally in the pcm. To test you need to first set your multimeter to DCV then put the red lead to the pin on the purple coil connector wire, put the black lead to battery negative and turn ignition on (don’t start the engine). All 8 purple wires should show ~11.8v-12.0v. Next, set your multi meter to continuity/resistance and probe the other wire in the coil connector ( the one that’s a different color on each coil) with the black lead and hold the other lead to the battery ground. If you have continuity then you either have a failed pcm or a signal wire shorted to ground. The rule out the wire short you need to disconnect the battery and unplug the pcm. Check for ground continuity again with the pcm disconnect and if it doesn’t show continuity, the pcm is the cause. I’ll attach the wiring diagram for the coils and the connector pin out for the relevant pcm connector.

P.S. make sure that the multimeter probe is small enough to actually touch the pin inside the connector without getting caught on the connector housing. If not, use a paper clip and an alligator clamp but be careful not to damage the pin

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A154662C-DE70-4437-9E20-81DB9E6CA002.jpeg
 
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Cobra Jet

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Just diagnosed this issue on my fbo E-85 2015 Gt.
These engine run on two wire coils, the one constant wire found between all 8 coils is the violet wire which gets a constant 12v with the ignition on. while the the other wire is a different color on each coil, these wires go to the pcm. The pcm sends a ground signal through the different coloured wires based on the crank position sensor, completing the circuit momentarily, giving spark. This should not be grounded with the engine not running and if grounded, indicates either a short to ground in the harness or internally in the pcm. To test you need to first set your multimeter to DCV then put the red lead to the pin on the purple coil connector wire, put the black lead to battery negative and turn ignition on (don’t start the engine). All 8 purple wires should show ~11.8v-12.0v. Next, set your multi meter to continuity/resistance and probe the other wire in the coil connector ( the one that’s a different color on each coil) with the black lead and hold the other lead to the battery ground. If you have continuity then you either have a failed pcm or a signal wire shorted to ground. The rule out the wire short you need to disconnect the battery and unplug the pcm. Check for ground continuity again with the pcm disconnect and if it doesn’t show continuity, the pcm is the cause. I’ll attach the wiring diagram for the coils and the connector pin out for the relevant pcm connector.

P.S. make sure that the multimeter probe is small enough to actually touch the pin inside the connector without getting caught on the connector housing. If not, use a paper clip and an alligator clamp but be careful not to damage the pin

7D85F2EE-E36E-40CF-91DC-4BDCB7F4BC1E.jpeg


5601CD9B-9CA5-4E24-8B6B-9CC9866B64EF.jpeg


A154662C-DE70-4437-9E20-81DB9E6CA002.jpeg
Excellent info - and for whatever reason there seems to be a rash of melted coils and PCM failures.

Is the PCM getting wet from water intrusion somewhere? Why would the PCM be failing so early considering most last the lifetime of the vehicle?
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