Hey, there, folks! Sure hoping someone has got some wisdom I can draw from.

First things first: 1999 F150, 4.6L V8, 2WD, Automatic, XLT, 190K miles; bought a year ago, seller said engine was replaced in early 2015 with 4.6L V8 from Crown Vic.
I'm a relative novice, trying to puzzle out a P0353/P0131.

I've been reading a number of threads here regarding this stubborn P0353, and while a couple have been helpful in steering my troubleshooting, I feel like my situation is just a bit different.

The truck has been running great since I first bought it. No issues at all. 2 weeks ago, was driving home at night, and inside of about a 5 minute window on a 30 minute highway drive, suddenly presented two problems: the A/C compressor stopped cooling the air, and the truck was suddenly working much harder to remain at 65 than it usually does. Began to shudder about 70 and down around 50. Pulled off the highway, and the truck died as I decelerated to the first stop light. From then to the house, it was trying to die the whole way, shuddering badly at low speed/RPM. Next day, threw a P0353 , Primary/Secondary Coil Fault at Cylinder #3.
This is how it drives, now. Consistently, the truck shudders at low load and around 45/50, dies unless I keep a little gas on it. Before I could make it to Autozone, since it felt like 3 different problems all at once, I went ahead and cleaned out the throttle body real nicely, checked for vacuum leaks. Took it to Autozone, and it was throwing a new code, P0131 -- Intake Air Temperature Sensor. Perhaps this was causing the ignition problem? So I bought a new one, changed it in the parking lot. No difference. Still throwing a P0131. Also swapped coils 2 & 3, based on some of the advice I've encountered on this forum. No change. Still throwing a P0353. Ran out of time, so failed to change plugs. I'll do that this coming weekend, also per the forum's advice. Incidentally, the shuddering is a constant, sometimes violent shudder. It doesn't feel like that periodic hiccup in the engine that I always understood indicates a miss. It's worse.

Since the replacement of the IATS and swapping of the coils didn't make a difference, what are the chances the PCM is bad? Sure would like a cheap fix..

Also, is there something I'm missing that could cause the A/C compressor to fail at the same time as the coil/IAT/PCM (or whatever is the main problem)? Would a failure in the PCM do this?

Thanks in advance for all of your help!
Matt

 

Read this:
https://www.obd-codes.com/p0353

continuuing to drive it while missing could ruin the cats.

 

The PCM's programming will automatically disable the AC compressor in the presence of a severe misfire. Fix the misfire and the AC issue should go away.

P0353 indicates an electrical circuit fault with the PRIMARY side of the ignition coil on #3. Check the electrical connector for secure seating as well as the wires immediately adjacent to to the coil connector as they can develop intermittent opens inside the insulation.

 

Thanks, fellas. Good advice! I took the bus this morning to work, per your advice, Roadie. Yeesh... I hadn't considered a CC issue down the road.
Thanks, projectSHO89, for explaining the relationship of the compressor to the P0353! I was sure hoping there was a single root problem.

I have read some articles on the P0353, which is why I swapped the 2 & 3 out. But the code read the same. If I swap the two of them, and the bad coil that was on the #3 is now on the #2, the code should then read P0352, right? It didn't, though. It still read P0353, which is why I was wondering about the PCM. Is there something I'm missing, there? Additionally, again, it also gave a P0131, but when I replaced the IATS, it didn't change, either. I suppose they could both be caused by a wiring/connectivity issue at the PCM, right? Especially if they share a wiring harness? I'm typing out loud, here, and following your counsel, so bear with me... might a single misconnected harness be the root cause of all three issues (P0353, P0131, A/C compressor)?

Matt

 

Your P0131 points toward a faulty O2 sensor or its wiring - bank 1 sensor 1, which is the upstream one on the passenger side.

If the coil is okay, then it's a plug, injector, or wiring to the coil or injector.

I'm surprised you have a COP system in a 99 with a 4.6 - it either originally came with a 5.4 or it's been modified. The 99 with 4.6 used dual coil packs and plug wires.

 

Well, this is mildly embarrassing. The guy who first ran the codes on the truck explained my "coil-on-plug" issue. We moved forward assuming this was the problem. But dad-gum, you're right, glc... 2 4-banger coil packs. There are no coils on the plugs. Feel a little silly. So this is what happens when your novice under the hood relies on the assistance of some friends real familiar with older engines, not so much with newer ones...

Anyway... so, tomorrow night, I'll skip the friends. Get under the hood, identify the spark-plug wire that connects the left coil-pack #3 to the #3 cylinder (3rd from the front on the passenger side, right?). Would the P0353 be caused by a faulty plug wire? Can I swap the plug wires between the #2 and #3 to see if the code follows it? Or does the tool know that this is happening INSIDE the coil pack? Either way, Thursday night, replacing the plugs and wires.

Last thing... that should have been a P0113 it pulled. Not a P0131. Autozone specifically said faulty IATS.

Thanks, again, for being patient with a noob.
Matt

 

Yes.

Very unlikely.

The P0353 does NOT relate to cylinder #3, it relates to COIL#3 (of four) which fires cylinders 4 & 7 (waste spark system). Coil #3 is driven by PCM coil driver 3 (CD-3) which comes out of the PCM on pin 78 (PK/WH wire). You can (CAREFULLY!) swap the coils and see if the fault moves to a P0351 (bad coil) or not (PCM or wiring concern). Make sure you tag the wires before removing them from each coil and then take a photo. Don't ask me how I learned that....


For the P0113, you're going to need to up your game by getting a tool that will read real-time OBDII data. An android device, a $20 BT interface, and a free or $5 app is usually what it will take. Most likely, you have a wiring concern, perhaps a wire was damaged when the engine was swapped and finally failed recently.

 

Recommend you use Motorcraft plugs and wires.

 

Man... thanks for the quick responses!

Forgive me, but I don't think this is true of my engine. I've got 2 coil packs, each hosting 4 spark plug wires. Each wire terminates at one spark plug. Here's what I see when I open the hood:



... except that it look like an actual engine under there. Not a diagram.
I'm gonna guess the same way I learned not to fiddle with brake rotors immediately after driving...!
Tomorrow evening, I'll swap 'em and see what happens. To be clear, this means swapping the entire wire, correct?

I see a number of them available for around $20 on Amazon. Any manufacturer recommendations?

Thanks, again! This has already given me some great direction going forward!

 

Google "Ford waste spark system".

 

Mark each of your plug wires with a piece of numbered masking tape. Pull all 8 out of the coils, then disconnect the connectors from the coils, unbolt and physically swap them, putting the coils and wires back exactly the same way they came out.