I first bought my 2012 Mustang GT/CS in December of 2013 with 40k miles. It was a Ford Certified Pre-Owned car that had been traded in for something else at this Ford dealer.
The very first time I NOTICED what I would later learn to be the "BBQ Lighter / Igniter" tick was shortly after the first oil change at my nearest dealer. I came back the next day and had them look at it. They definitely didn't claim it as being "normal" since it was so noticeable nor gave me BS runaround at the time, but after dropping it off for a few days of tests and troubleshooting they chalked it up to bad gas and ran some injector cleaner through it.
Sure enough, the ticking had gone away mostly when I went to pick it up, but it was still very faintly there. It didn't really bother me then as I thought it was taken care of. Of course, I would later learn the only reason it went away was because they beat the **** out of the car when running the cleaner and "broke" in the new oil.
After the next oil change a few months later it was back again. It was SO LOUD in parking garages and drive-thru's to the point it was embarrassing. I took it right back and had them look at it again. They inspected all timing components this time, but didn't replace anything. They said it had no TSB's either. Sure enough, they said it was carbon buildup ping again. "Dammit, HOW is that so?! I ONLY ever use top-tier 93!" I said. They once again ran carbon cleaner through it which made the tick go away and they said that they're done troubleshooting this issue and if I bring it back again for the same thing i'd have to pay for the shop time and cleaning service. I was pissed, but I trusted their word and made sure to get everything written down on paper in case I had any issues in the future after my warranty was up.
So I just let it be for the remainder of 2014. It would go through the cycle just like everyone else has described here and the noise really settles down towards the end of the oil change interval. In the winter it was barely noticeable at all, EVEN AFTER AN OIL CHANGE. Texas summers are brutal, so as soon it started getting warm out in 2015 the ticking started again after an oil change and this time, it was different. Not only did I have the ticking sound, but I would start to feel a very slight stumble in idle - not like a misfire but like drop in RPM due to load (very very small amount, most wouldnt notice it). The hotter it was outside the worse that it was. A/C on or off, it didn't change the sound. NOTE: Rapid ticking/tapping sound was present at highway speeds while cruising!!!
This was in March and now I was getting worried on top of my frustrations. I was about to just go ahead and trade in the car for a 2015 GT.
I started documenting and recording videos of the sound after I learned about so many other people having this issue. Here are some videos: Pulling into an alley/service bay, starts at the 0:09 sec mark https://youtu.be/bFWEihLehBE In my driveway at home after running some errands https://youtu.be/WfI5vRA43GU A/C on or off - slight rev/load https://youtu.be/wT3KNuUs1m8 Noise heard WHILE DRIVING at the 0:20 sec mark and then at the light https://youtu.be/ZlpfUPreIZc Constant tick heard in the parking garage https://youtu.be/TggLtSVZoDk
So I recently moved to another city in TX and decided to try another dealer, ONE LAST TIME. I had an oil change done, ticking was back with a vengeance, called the master service adviser to explain my previous situation and to make an appointment to have it looked at under warranty. That morning I warmed up the car reeeaaal good, had the service adviser look at it, and sure enough he heard it and immediately said it would be looked at under the "heavy" line of repairs. They hook me up with a rental and I head out. He calls back the next day and said this is something they've seen before and it will most likely need a short block, but before they do so they need to get with Ford's hotline and run through a testing process. We are now at early-mid April of 2015 and the nervous waiting begins.
I get called back a few weeks later, and I'M GETTING A NEW SHORT BLOCK under warranty! I was elated. Excited beyond words. I instantly breathed a sigh of relief. I felt like I had WON something, as ridiculous as it sounds. I talked to the adviser after the parts came in and everything and he said they had seen this in a 5.0 before and it had also gotten the short block replaced and that customer never returned for the issue and still gets serviced there.
So here I am today about to go pickup my car in a little while and will pray to the almighty lord that I can finally move forward with my plans with the car in keeping it for a while.
----------------------------------- CLIFF NOTES
-Bought a CPO 2012 GT/CS in Dec. 2013 w/ 7yr, 100k mile warranty
-BBQ tick started after first oil change.
-My original dealer back home gave me the runaround after looking at it a few times (basically after they got annoyed with me bothering them)
-Moved to a new city and brought the car in to get looked at one last time, but this new one acknowledged right away and sent it to the heavy repair line for diagnosis.
-After 3 weeks of waiting I am authorized a new short block and it gets fixed under warranty.