So hello to all again lol after this site helped me to fix a previous problem, I again find myself with a electrical problem haha On my way to work this morning the truck did a misfire and flashing cel, so after work it did it again 2 / 3 times on the way home to read the codes, the 2 I'm having a problem with is p0302 (cyl 2 misfire) and p0351/353/354/357/358 Ign coil a/c/d/g/h - how come cylinder 2 is the only ignition coil not affected if the misfire is there? Am I missing something? Plugs 12348 were done about 5 months ago. Prolly no factory ones left, as I bought it used.

 

Why didn't you replace plugs 5, 6, and 7?

What year and engine and how many miles on it?

 

Sorry, motor is 5.4, year is unknown (was replaced by previous owner) roughly 160xxxkms, trucks an 06 Lariat, I started doing the plugs but had to take it to a shop for manifold work so 5,6,7 plugs had to wait. And I must have forgotten 😐

 

@Dave5.4 , there is a big difference between P030x and P035x though both ignition related. There is an enormous amount of smarts going on in the PCM. It would be so nice to have flow charts or programming notes from the programmers of the PCM. But we are left to figure this s@#$&T out for ourselves.


The COP primary is 'sourced' with +12v. Assuming the coil primary is intact and electrically connected, the PCM is able to see the +12v arrive at its input terminal and thus - determine the wiring to the coil is good. If NOT, the PCM does not energize the injector for that cyl. This is to avoid flooding the cylinder and protect the CAT from getting a dose of unburned fuel, because the PCM 'knows' it can't fire that plug. Under this scenario you get a P035x code. Technically THAT is not a misfire (P030x), it is a circuit problem. ///This makes me think you need to inspect electrical integrity of the little snaps on COPs and of the common wire to your COPs, including your "Hot in Run/Start" circuit from ignition. You have way too many COPs reporting circuit problems. ////


If the primary circuit appears intact, and the PCM pulls the COP's ground terminal to ground for normal ignition operation - When it 'releases' it, the PCM circuitry is designed to further enable the PCM to watch for the powerful 'electrical kickback' (a spike of hundreds of volts) that will occur when the Coil produces a actual spark. Believe it or not - the PCM actually determines a misfire (P030x) by observing the dip (slight reduction) in crankshaft rotational velocity immediately after commanding a spark. At that instant, if it did not see that R.E.M.F, it reports the event as a P035x - assuming a circuit problem in the secondary windings of the COP circuit. Note: the description of P035x is primary or secondary circuit problem.


Otherwise ---- the PCM applies more logic -----. If it is a P030x (failure to ignite fuel/air mixture) and within the first 1000 engine revolutions of this run cycle, it IGNORES it and does not add it to misfire count. After 1000 revs, this event is added to a misfire count and ran through a 'weighted moving average' of the counts and compares it to a factory set threshold to determine if it should report a P030x DTC and/or Flash the CEL as a potential CAT damaging condition exists.


With your P035x codes all mixed in there with the P0302 - I wonder if it is not a corroded or flaky connection(s) somewhere and would focus on that as part of a good clean plug job on all 8 plugs.


BTW - welcome back!

 

@F150Torqued- thanks for the advice and area to start. I did notice yesterday one of the clips was broken (broke as I removed it) that holds the socket on the COP. And upon further inspection some of the rubber grommets were also falling apart/missing. The morning I got the flashing CEL was a cool damp morning (not do much from rain but from a large drop in temps (22C to 6C) over night. I will pick up some new sockets and change them to be on the safe side.

 

That flashing CEL is a bad thing. Try to eliminate the cause as soon as reasonably possible. Never know how much of that a CAT can tolerate before melting or coming apart.


Sounds like the condition / life of your plugs is uncertain. I might also just spring for a set of all new "Motorcraft" plugs with new Boots/springs, just to know where I stood. If you do - I have a rather different/radical theory about the unusual plug design on these engines. You can review it FWIW here:https://www.f150online.com/forums/v8...ml#post5159499 It has been the permanent CURE for me. Too many guys replace plugs on these things only to continue having random misfire problems.


A side note on my prior post. I was trying to "PROVE" a point to a forum member about flashing CEL & Fuel Trim (Rich/Lean) indications resulting from 'misfires' by using my Torque Pro scanner while I unplugged COPs. I got a hell-of-a-surprise when I learned the PCM wouldn't give me a 'misfire' indication, but would simply shut down THAT injector, increase throttle plate positioning (barely dropping any rpm's), drop OUT of closed loop - and keep running surprisingly well while producing ONLY a P035x code representing the COP I had unplugged. Damn thing's smarter than I am!

 

Visually inspect the harness, then test and verify engine and body grounds


I don't know that the engine would actually run on just cylinders 2, 5 and 6 (Assuming that the reported circuit failures are accurate)

Might have a failing PCM?

 

I bet he'd for sure know something was wrong if it was. But one of the 'curves' OBD codes seem to throw at us OFTEN is that many DTC's (including P035x) are "STICKY". Various different ones take multiple run cycles, or even drive cycles, to clear without a code reader or battery disconnect. Cleaning ALL grounds seems a very good idea to me. Seems like the problem may be intermittent and that's a good place to look.