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Discussion Starter · #1 ·
I have a 2001 3.0 OHC engine and changed the plug wires, I now have a misfire. It's quite possible I misrouted a spark plug wire. The coil is marked as seen below facing the engine. I'm running the wires as marked on the coil to the cylinders.

1-2-3
5-6-4

Is this correct or an I doing something else wrong?
 

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I have a 2001 3.0 OHC engine and changed the plug wires, I now have a misfire. It's quite possible I misrouted a spark plug wire. The coil is marked as seen below facing the engine. I'm running the wires as marked on the coil to the cylinders.

1-2-3
5-6-4

Is this correct or an I doing something else wrong?
Cylinder layout is as follows.

Firewall
123
456
Radiator
 

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So should the wires from the coil be layed out the same?
The wires, as marked on the coilpack, should go to the engine cyls as layed out in 00tec-satx post. The firewall being cyl bank one, the radiator side being bank two.

So, no the coil pack's cyl number layout position isn't exactally like the engine cyl number layout. So you likely have the radiator bank plug wires on the wrong cyls.

The coilpack only has 3 secondary coils, to fire 6 spark plugs. So the cylinders are paired together to share the same ignition coil so that they'll work together in a "waste spark" ignition system. Saves the factory some money, by having one coil fire two plugs!!!!

The coilpack pairs cylinders to work in a "waste spark" configuration, such that when for example, cyl 1 is firing on it's power stroke, it's companion cyl #5, is being fired on it's exhaust stroke (waste spark), same for cyls 2/6 & 3/4 being paired together, to share the same secondary ignition coil!!!!
 

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Wires

The wires, as marked on the coilpack, should go to the engine cyls as layed out in 00tec-satx post. The firewall being cyl bank one, the radiator side being bank two.

So, no the coil pack's cyl number layout position isn't exactally like the engine cyl number layout. So you likely have the radiator bank plug wires on the wrong cyls.

The coilpack only has 3 secondary coils, to fire 6 spark plugs. So the cylinders are paired together to share the same ignition coil so that they'll work together in a "waste spark" ignition system. Saves the factory some money, by having one coil fire two plugs!!!!

The coilpack pairs cylinders to work in a "waste spark" configuration, such that when for example, cyl 1 is firing on it's power stroke, it's companion cyl #5, is being fired on it's exhaust stroke (waste spark), same for cyls 2/6 & 3/4 being paired together, to share the same secondary ignition coil!!!!

Good call good explanation.

Since most small engines have used "waste spark" for ever, no reason for cars to not use also. Makes the plugs work overtime! Been quite successful in eliminating the distributor. And a Dist is one more thing to fail, get wet, crack, and have bad bearings. Like the sync that replaced it.

Happy ignition!

-chart-
 

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If you misrouted the wires, the car will run like TOTAL CRAP not jsut set a code, by that I mean engine will shake, and have a very significant loss of power. The exhaust will also sound horrible.
 

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Discussion Starter · #8 ·
The wires are routed correctly. I keep getting a #5 cylinder misfire. I swapped injectors with another cylinder with no help.
 

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The wires are routed correctly. I keep getting a #5 cylinder misfire. I swapped injectors with another cylinder with no help.
Since this just happened upon the plug/wire change, try swapping a wire from another cylinder to #5. You may have received a bad wire.
 

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Pull the #5 plug and carefully inspect it. Is the gap correct? Carefully inspect the insulator for hairline cracks. Ohm out the #5 plug wire to be sure resistance is in spec and that the wire isnt laying on the exhaust manifold, etc.

Had a similar experience a week ago changing plugs in my 02 Grand Prix GT (Autolite APP606). After the change, it had an obvious miss. I didnt wait for it to set a missfire code, as I didnt want to risk cat damage. Wires checked out OK. I pulled all the plugs and carefully inspected each again (I always give them a quick inspection before installing plugs). One plug had a small hairline crack in the insulator I missed on initial inspection. I replaced that plug (had 2 extra as I bought 2 boxes of 4), and it ran perfect. In 40 years of working on cars, this is the third or fourth time I have gotten a plug that was bad out of the box.
 

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Ing error

Pull the #5 plug and carefully inspect it. Is the gap correct? Carefully inspect the insulator for hairline cracks. Ohm out the #5 plug wire to be sure resistance is in spec and that the wire isnt laying on the exhaust manifold, etc.

Had a similar experience a week ago changing plugs in my 02 Grand Prix GT (Autolite APP606). After the change, it had an obvious miss. I didnt wait for it to set a missfire code, as I didnt want to risk cat damage. Wires checked out OK. I pulled all the plugs and carefully inspected each again (I always give them a quick inspection before installing plugs). One plug had a small hairline crack in the insulator I missed on initial inspection. I replaced that plug (had 2 extra as I bought 2 boxes of 4), and it ran perfect. In 40 years of working on cars, this is the third or fourth time I have gotten a plug that was bad out of the box.

The old AM radio test would tell you quickly if you have a wire/plug issue. Cannot tell which one, but narrows it down to that or the coil pack.

Happy ign.

-chart-
 

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The Dealers lead tech cracked a #6 plug on my then new 99 Ranger. It would randomly misfire in the wet, so they did a wetdown test with a spray bottle of 5% solution of salt water, of each plug wire & coilpack, to find the #6 cyl had a problem.
Plug inspection revealed a hairline crack in the external insulator, like jeff mentioned.

If no joy with the wetdown test, maybe also do an end to end continuity test on the #5 plug wire, while wiggeling it. The reading should remain steady at about 1000 ohms/inch of length, 30K ohms max.
Or swap it out with the old # 5 plug wire & see if the misfire goes away, or as has been said, swap the #5 wire into another cyl & see if the misfire follows the wire.

More thoughts for consideration, let us know how it goes.
 

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Discussion Starter · #13 · (Edited)
SPARK PLUG!!!!!! Duh, on my part. The plugs had about 10K miles on them so I naturally didn't think they were the problem. I THOUGHT I had swapped plugs with another cylinder to see if the problem followed. This morning I really did swap the #5 with #6 and the problem followed. I put a new plug in and she runs beautiful!!!!!!!

The whole thing started months ago with a litle miss during warmup, with a little hic-up while driving at speed. The plug wires had 141K on them so I thought I would do a little preventive maintenance and change them. The miss really got bad then so I figured I did something wrong while swapping wires.

No visible sign of damage to the old spark plug....

Lesson learned, only change one thing at a time while troubleshooting.

Thanks for the help!
 

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SPARK PLUG!!!!!! Duh, on my part. The plugs had about 10K miles on them so I naturally didn't think they were the problem. I THOUGHT I had swapped plugs with another cylinder to see if the problem followed. This morning I really did swap the #5 with #6 and the problem followed. I put a new plug in and she runs beautiful!!!!!!!

The whole thing started months ago with a litle miss during warmup, with a little hic-up while driving at speed. The plug wires had 141K on them so I thought I would do a little preventive maintenance and change them. The miss really got bad then so I figured I did something wrong while swapping wires.

No visible sign of damage to the old spark plug....

Lesson learned, only change one thing at a time while troubleshooting.

Thanks for the help!
Good trouble shooting & feedback & to hear you have it squared away.
 
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