So tonight on my way home coming up my hill a few getting from my house my tuck all of a sudden developed a horrible misfire. Now im pretty familiar with swapping coils and have replaced them years ago with the ebay set for $80 or whatever so I have the stock ones to swap out if need be. Anyways I scanned and got the codes p0351 p0352 p0353 and p0357. After doing some research on here I pulled the battery and pulled the PCM connector and everything was nice and clean and shiny like the day it was made. After hooking it all back up and starting it somehow it's now just down to the p0353 code. It really doesn't seem to run any better and pulling the no.1 coil as well as the no.3 make no difference in idle. Also tried swapping a few coils around as well. I have checked the harness where it runs by the accumulator and it looks fine.. Any other ideas guys? I called it a night as its getting dark and cold and have ran out of ideas myself... :-/

It is an 02 F150 4.6L 4x4...

 

How many miles on the plugs and what brand are they?

 

I have no idea if they've ever been changed. Truck has 98k on it. Not sure if I dare change the plug with my bad luck...coils have dialectric grease as well and look good. I suppose tomorrow I will do light/meter tests

 

The plugs are hard to get to but they don't break like the 3V engines. Just torque the new ones to 28 ft lbs. Use Motorcraft plugs.

 

With 98k I'd bet they are original and need to be changed. Motorcraft, no antiseize, 28 ft/lb. Change the plugs before you keep chasing coil issues. No way to test coils without some specialized equipment.

 

I don't think there is a way to test the coils at all. I would change the plugs and really if it were me I would go out and find the best set of cils I could aford and just replace them all. You DON'T have to do that. You could just replace the # 3 coil and do the plugs and the engine would probably run fine.

 

Any tips to changing the plugs? Spray down holes with pb blaster? Special extensions/swivel sockets for the rear cylinders? I know them rear two were a pain when I did the coils...

 

For 1/3 or 1/5th the price of one coil, this thingy' will test a coil and indicate approximately the secondary output voltage. If your getting a 20k or 30k volt spark, it darned sure should fire a plug. Only downside it presents is it has to be used with the COP off the plug during the test and will create a P030x code, and if ran too long that way (how long???), the ECU will shut down the injector for that cylinder. But on the next ignition cycle it'll come back on.


BUT @machsp33d 's codes are in the 0350 series - "Primary / Secondary circuit fault" On multiple cylinders I would vote for "primary", and that indicates a problem (open or short or high resistance connection) in the wiring from the PCM to the COP. He was correct in checking that out first - and should continue to focus there till those codes are removed.


Some guys advocate NOID lights to test primary, but I don't like them because they require too little current to light, and can miss a high resistance circuit caused by corroded connection in the circuit. I prefer a pin through the switched wire at the COP plug and monitor it with an analogue VOL while idling. You can see the 12v reading 'bobble' downward when the PCM is firing that coil if there is GOOD continuity from the PCM to the COP (it's just too fast for the VOM to ever indicate zero - a scope would be best, but most of us ain't got one).


But.... the 350 codes say PCM is sensing too little or too much current in the COP primary circuit. (Those damn plastic clips on top of the PCMs have a habit of breaking and the rubber insulators in the clip push the plug back up where it looses connection or corrodes and makes poor connection). Or with codes on all cyls on the same bank, it would most likely be in HOT wire from the PCM.


Good luck, hope this helps.

 

No spraying required. These plugs come out easily. If there is dirt/crud in the spark plug hole you may want to blow the hole out with an air source before removing the plug. I didn't do this. My engine was clean. When I replaced the plugs in my 02 5.4L, I did not need any swivel sockets. I did have to pull the injector rail on the driver's side. Your 4.6L may be a little different.

 

Again - the plug sticking issue is only on the 04-08 5.4 3 valve engines.

 

I ran out on my lunch and checked the pcm fuses under the hood and dash real quick and they were not blown. So this would mean that I don't have a wire rubbing on anything would it?

 

Well - probably for 99% probability it would. The multiple cyl 035x codes would require the short to be on multiple COP circuits (very unlikely) or on the common side, which appears (according to my '04 wiring diagram) to be common to ALL 8 COPS and go to a circuit in the Right "A" Post kick panel that's hot all the time in Start & Run. A a short in that wire would almost certainly blow a fuse and probably kill some other stuff.

I certainly do not mean to POO-POO others poster's suggestion / questions about plugs, and they certainly may need to be replaced. But I'm going by the reported p0351 p0352 p0353 and p0357 DTC codes - and assuming they aren't a "HARD" miss, The ECU can tell the difference between a misfire caused by, say a fuel/air problem, and an electrical failure preventing the coil to fire. The first produces a 0301 - 0308 DTCs, the latter 0351 - 0358. It's hard to second guess a programmers logic here - because BOTH instances result in a misfire (I think the ECU detects that by sensing a small variation - or dip in crankshaft rotation speed as determined by the crankshaft tone ring and CKP sensor).


So I think the programmers must have given the 0351-0358 higher reporting priority because the ECU can actually determine the difference - and if 'current' flowed in the COP circuits or not. If so, the COP secondary should put out a blast of high energy spark, and cause the plug to do something. Even if plug electrode is 'fouled' with carbon or oil deposits and "conducts" the current without creating an open spark, to the ECU it still looks like a 030x.


If we still are dealing with the same codes / and the miss isn't HARD on one COP - IMO the problem is in in electrical connections / wiring somewhere as there just isn't much inside a COP to wear out, deteriorate, burn out, or degrade with time. They are basically just two coils of wire wrapped around an iron core and sealed in epoxy. That's why I like my AMPRO coil tester.

 

I got home tonight and swapped out the #3 coil with a other and still have the code. Also pulled the battery and unhooked pcm and took compressor to blow off anything that I couldn't see and still no change. I did a diy noid test on the #3 plug with a 192 bulb and did not light up so looks like no power to the coil? I once again double checked the harness along the valve cover to down by the accumulator and to where it plugs into the compressor underneath as well as between the firewall and the engine and o2 wires are clear or exhaust and driveshaft. I'm about to let this truck roll down the hill into the concrete wall at the bottom before I pay the stealership! Lucky it's going to be nice enough to ride my harley til I can think this over i guess...thanks and sorry guys getting really frustrated with this truck nickel and dime me!

 

I feel your frustration and sympathize, I'm sorry.


Not sure how your test with the 192 bulb was done but the concept has lots of pitfalls - and if done incorrectly could potentially damage the PCM.


Electrically speaking, the wiring to the COPS has one hot wire supplying 12v Hot to ALL COPS when ignition is ON or START. (Do not know for sure on your vehicle but should have some red on it, maybe Red/Yellow). While I definitely prefer you be using a Volt Ohm Meter, connecting your bulb from 'THAT' wire to battery ground should light your bulb. The other wire is 'floating' - an 'open' switch inside the PCM until it wants to 'fire' that plug. When the COP connector is unplugged, it has NO voltage sourced to that wire from the PCM and would not light a bulb, or even give a reading on a VOM. With COP plug connected, your VOM 'should' read 12v on both sides of the connector to ground. I can't say for sure the switched wire (the switched wire) would even light up your test bulb to ground. It certainly wouldn't with the connector unplugged. With it plugged, you might not get enough current through the coil primary circuit to even light the filament in the bulb. Basically - the bulb is a BAD test tool.


During normal operation, the PCM circuitry (closes a switch) - & pulls this wire to ground to draw current through the COP primary circuit and fire the coil. It will not harm the PCM if you short this wire to ground momentarily to 'fire' the coil. You can actually test them this way.


But I would say DO NOT try to connect the bulb in place of the COP. IT WON'T LIGHT. A light bulb, no matter how small, is a DIRECT short until the filament heats up to white hot - and would very likely blow the circuitry inside the PCM if you tried to run the engine to see if the light flashed. IT WON'T LIGHT because if it didn't blow the PCM circuit, the pulse width is much too short for the bulb's filament to ever get white hot and light up. This is why NOID lites are used.


You can however see a little 'bobble' in the 12 volt DC reading with a decent VOM while the engine is idling without damaging the PCM -- "IF" the circuit wiring / connections / to the PCM, and the PCM output circuit is electronically good and working.

 

Those tester don't work on coils that are failing intermittently fact is many coils that are flat out junk will test as good. The only thing that works is a stress test on a good diagnostic scan tool That shows live missfire counts. The 35x codes are almost always a coil. I'd change the plugs because they are due. Rarely is it a wiring or other issue. I personally have dealt with several 35x codes. every time it was a coil.