AC and P0354 Ignition Coil D Primary circuit fault
Sorry this is long but it could save you hundreds. I just thought I would post this as I'm sure it has happened before and will certainly happen again (just not to me). Hopefully, it will save someone time, money and aggravation. The issue here is something that leaves me questioning Ford engineering. Ok, so here we go. I have a 2008 Expedition EL and this past Friday while on the interstate I noticed my air not as cold as usual, at the same time I noticed a hesitation / stumble at speed. Upon exiting, at idle, the car had a bad miss and the AC now was nothing, just blowing hot air. It wasn't until I made it home (which was only a few miles away that the amber engine light came on. Ok, off to Advance and I will have the code read to figure out what was going on. The guy at advance relayed the code to me (P054 Ignition Coil D Primary circuit failure) and promptly informed me that the likely culprit was the coil pac as they are notorious for going bad on the 5.4. Although he did not know which cylinder I later deternined D was #4 on the pass. side closest to the firewall. Great, I thought $45 and some struggling against the firewall and I will have fixed one of the two isssues.
So, what happened to my AC? Maybe I have a leak and just need to recharge it I thought, but after looking into it, the compressor would not engage. Perfect, $300 plus to fix that one.
Oh well, back to the coil pac, in 15 minutes the new one was installed the truck fired up and..yep, still a miss. So, maybe the plug is bad and not firing. This in itself is a crime, the plug could not be found locally. Seems that Ford had an issue with plugs and mid 08 changed to a different design, of course no one had it except the local Ford dealer. Yep, $20 later and I had ONE plug (so between coil pacs and plugs this thing would be a $500+ tune up). Anyway, back to the truck to swap out the plug..you guessed it, fired it up and still a miss. So what is going on? Only then, after spending $70 and many choice words the problem revealed itself. When unhooking the connection to the coil pac for the third time, the BS tape used to guard the wires peeled back and there it was bald copper with a millimeter of just plain yellow insulation. How did this happen? A quick look at the AC lines and the puzzle was over. The wires in all their natural glory laid up next to the AC line, which got hot and melted the insulation and wire, killing #4 and grounding the compressor all at once. Two seemingly different problems yet, one cause. After struggling to reconnect the broken yellow lead and placing a 1 cent cable tie to keep it off of the AC line all is well. Cold AC and no miss. Now I can only wonder how much my local dealer would have taken me for. So, if your AC quits and you get a miss on #4, maybe you can save the $70 I spent and come away with only a modest dent in your electrical tape roll and a 1 cent cable tie!
Just had to post a huge thank you! My 2008 just did the same thing and sure enough, it was the same wire. We checked it first after reading your post. You definately saved us alot of time and money. Just had to say thanks a bunch!
Thanks from My family too. We have a 07 Expedition w/ the same problem. The link above should take you to a picture of mine. I do have to disagree however w/ the cause of the A/C not working. I pulled my wires loose and started the vehicle still had the miss and no A/C. I then reconnected the rubbed in half wire and restarted. Everything worked again. My theory is that when the engine gets the dead miss from the wire being severed the computer cuts out the accessory that requires alot of horsepower in order to maintain as much as it can. Thanks again!
Thank you for posting this thread!! Exact same problems on my 2007 Expedition. Yellow wire was completely burned through. I spliced in another yellow wire I had laying around and wrapped it up good with electrical tape. Taped the lead to the harness so it would not happen again.
Why on earth do these problems always occur in the back of the engine compartment with tight access
Wow, thanks 1lrover1 for the post. I know you posted it two years ago, but it was my situation exactly! I replaced the ignition coil because the code said #4 was bad, then when that didn't fix it I started to switch coils to see if the coil I bought was bad. That wasn't it. Returned the coil and searched the internet for a second time. That is when I found this post. Went to the truck ('07 Expedition) and took a close look at the wires coming off of #4 and sure enough that was it. It was a bear to try and work in the tight space. I got two butt connectors and cut the two wires, reconnected with the butt connectors and started the truck to test my fix. Sure enough, no misfire and the AC was working again. Shut it off, taped the crap out of it with electrical tape and made sure it was it wasn't touching the AC line. Good to go. Dealer suggested the plugs needed to be changed and wanted $600. I spent $3 on the connectors! Dealer probably would have found the bad wire and not told me and still would have changed the plugs to make the money...not this time! Thanks again for the post.
I have had the same exact issues with my 02 Explorer. When i read your post i got so excited because we have been trying everything to figure out the problem! Now i haven't checked it out yet but pretty positive tart this could be our solution as well. We got the coffee for a #4 misfire and at the same time the AC started acting up and then we got the po354 code. I'm going check it this morning and I'll post the results.
this bugs me a little bit, in terms of what auto parts stores are doing now with offering free DTC reading. a competent mechanic would have known that the primary circuit on coil-on-plug ignition systems is pcm controlled and the primary circuit is between the pcm and the coil pack, not the coil pack itself, nor the spark plug. the coil pack to the plug is responsible for the secondary ignition. he takes a guess and sells you a coil pack because they are "common" for failing, which undoubtedly they are, but they shouldn't set that code. probably just a p0304 for the #4 misfire. then when that doesn't work he sells you a spark plug. they are getting people to throw parts at their vehicle based off of no real diagnostic troubleshooting. a DTC can point you in the direction of the problem, but there is still several variables to rule out: the component involved, wiring, the module controlling it, a potential sensor reading the component, or is it a cause and effect type of problem? is this trouble code being set because of some other problem? (like his grounded out wire) these parts stores diagnostic advice is free because they have no credibility or reputation to uphold nor do they make no claims about it. they'll put their 2 cents in on what they think it could be, sell you the part and their job is done. they don't have to worry about comebacks. "just throw this ignition coil at it, it'll work, and if it doesn't, i'll sell you a spark plug" and it that doesn't work? doesn't matter, you're not paying him for diagnosis, he did you a favor by reading your codes for free. the store has their money, once the box is open, that part is as good as used. Good on you 1lrover1 to do some diagnostic troubleshooting, which all it took was a thorough visual inspection.
Thank God for this thread!!! I had the exact same problem with 07 F-150 King Ranch. I drove the truck week before last and no problem. I parked it in the garage for a whole week and today I decided to drive it. It started fine and drove for about 5 miles then started acting like it had a bad coil pack and at the same time I noticed the AC was not blowing cool. first thought in my mind was rats chewed up a wire harness cause these were two separate systems, I couldn't see the connection. Anyway, I limped home and got my Waekon COP tester and low and behold it was indicating that it was the rear passenger side coil. I double checked with my OBDII tester and it told me that it was my #D could that was bad. So I got all the stuff to change it. I had a brand new set of coils sitting there waiting for one to fail, I had several issues before with coils. Anyway I decided to just see what this forum had to say about this issue. And low and behold I found this discussion thread about the exact same issues my truck was having.
I unplugged and removed the computer and started checking all the wiring harness by the AC lines. Low and behold there was wire bundle wedged between the AC lines and several bundles resting on the engine that had become brittle from the heat and in some places crumbled where it was just plain wire resting on the metal engine and AC lines. I didn't see any broken or exposed wires but I decided it could just be a minute area that I could see, so I retaped these wire bundles with electrical tape and then taped over the electrical tape with heat shield tape in the areas where the wire harness was real close to the AC Lines and engine metal. Put the computer back in and started it up.... No miss and the AC came right on!!! Thanks to this thread.
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