misfire code po351
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Freshman User
Joined: Jul 2006
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From: nepa
misfire code po351
I get a misfire code from my 2001 3.0 v6 that list as a primary coil problem. am I missing something here?? my engine has a coil pack on each cyl. so where is this primary coil hidden at ????? the only time I get this mifire is when the outside temp is around 20 degrees. no problem when its warm out.
Elder User
Joined: Nov 2008
Posts: 668
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From: Northfield, MI
If you have a coil on each plug, you have coil-on-plug, not a coil pack. A coil pack is 4-6 coils in one assembly and uses plug wires for connections, thus the term "pack." A google search is helpful for pictures.
The "Primary Coil" in this case refers to the low-voltage section of the coil. It also has a "Secondary Coil" where the high voltage is induced. The code simply means that there is a problem somewhere in the coil, the PCM, or the wiring and connectors in between them.
The easiest thing to do is remove the coil connector and make sure the pins are not pushed out, there is no water present, and the terminals are clean. If everything checks out, then you'll have to decide what to do next. Ideally you need to test the circuits while the concern is present to find the cause of the high resistance. If you can't do that, you will just have to guess.
In my experience, this code is almost always caused by a connector or wiring issue.
The "Primary Coil" in this case refers to the low-voltage section of the coil. It also has a "Secondary Coil" where the high voltage is induced. The code simply means that there is a problem somewhere in the coil, the PCM, or the wiring and connectors in between them.
The easiest thing to do is remove the coil connector and make sure the pins are not pushed out, there is no water present, and the terminals are clean. If everything checks out, then you'll have to decide what to do next. Ideally you need to test the circuits while the concern is present to find the cause of the high resistance. If you can't do that, you will just have to guess.
In my experience, this code is almost always caused by a connector or wiring issue.
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Freshman User
Joined: Jul 2006
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From: nepa
misfire
fireme thanks for the info i understand the coil pack thing and all I didn't think anyone would pick up on the mistake I made. I guess this is going to be one of those problems because it happens at wrong time when I can't check it out and it is only for a few secounds that it happens. thanks again
New User
Joined: Dec 2010
Posts: 23
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From: San Fran bay area
If you read my post on PO356, you'll see I have the same issue just an easier cyl. to get to. The first time it threw the code I eventually put in a new coil @ all new spark plugs and a manifold gasket set. It took about 1100 miles then ran rough for a split second and threw the same code again. I swapped coils around and ckd. that cyl. spark plug, all looked good, so I traced cyl.#6's leads back to the passenger side plug on PCM, pulling all the elec. plugs, cleaning the contacts and dielectric greasing all. So far it hasn't repeated but if it does I will go to the dealer as I've discovered this is still covered under emission warranty and I feel the problem lies either in the harness wiring or PCM itself. If it weren't covered, my next step would be to splice into the harness at the PCM and run my own wires directly to cyl. # 6 coil and then see if it does it again. Not sure why yours only does it when it's cold since mine doesn't have that issue..good luck..
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Joined: Jan 2002
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From: suburban atlanta
It is possible that the coil windings open up when the temperature gets that low. You could test that by getting the ohm readings when the coil is at room temperature, and then placing the coil in the freezer for 1/2 hour or so. Test the resistance when the coil is cold to see if the winding have the same resistance.
tom
tom
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