Need help: rough engine diagnosis

[Breeves002]

Copper plugs will work, but they won't last very long at all.

The computer will reset after a hundred or so miles, you should reset it.

If the misfire is still happening, then it's not going to turn off. Reset it, drive a while, and then read codes, even if the light doesn't come back on, they could be pending.

If it doesn't flash while driving, then it looks like the plug may have been the problem.

[behlinla]

I would reset the codes now and see what happens. I particularly want to know if P0351 comes back or not.

Also, did you confirm the spark was strong (jumping about an inch)? Did the spark sound regular on all cylinders or was it dropping out sometimes?

I don't know if I can trust the judgment of an auto parts store employee, but the plugs might also have been the factory single platinum plugs. With the waste spark system, they put the platinum on the electrode on one side and the platinum goes on the ground strap on the other side (can't remember which side has what). So if someone swapped factory plugs from the front bank to the rear bank they'll go bad in a hurry since the spark polarity is reversed.

I would plan on replacing all six plugs with double platinums (Autolite or Motorcraft plugs) when you figure out the misfire.

[jbh425]

I wasn't sure what I was looking for regarding the spark, but iirc all 6 seemed comparable at the ignition coil, and all jumped about 1" from the base of each well to the tester.

I disconnected the battery tonight to clear the codes. Noticed on startup that it is still a little rough, but much better than before. Will drive it for the next couple of days and then check the codes.

Regarding the spark plugs behlinla, are you saying that the plugs need to be installed with the correct polarity?

As a note, I noticed a couple of things worth mentioning while working under the hood:
1. there is a persistent ticking coming from somewhere near or above the #5 injector area. I couldn't isolate it.
2. there is a sound of air coming from the plastic box mounted high on the driver side firewall. I thoroughly inspected this, even removing it (but not disconnecting any hoses) but couldn't find any air leaks. Perhaps just the sound of air rushing inside those tubes?

Thanks all.

[behlinla]

When I talk about polarity I mean which way the spark fires (the direction of the electron flow). On one side the spark jumps from the center electrode to the ground strap, and on the other bank the spark fires from the strap to the center electrode. It will affect the wear pattern of the spark plugs. It's basically technical stuff that just means if you replace plugs use double platinums.

Originally Posted by jbh425

As a note, I noticed a couple of things worth mentioning while working under the hood:
1. there is a persistent ticking coming from somewhere near or above the #5 injector area. I couldn't isolate it.
2. there is a sound of air coming from the plastic box mounted high on the driver side firewall. I thoroughly inspected this, even removing it (but not disconnecting any hoses) but couldn't find any air leaks. Perhaps just the sound of air rushing inside those tubes?

1. Ticking might be the injector itself. Unplug the wire going to it and see if the noise goes away. The idle should get rougher.

2. Very interesting. What happens to the idle when you step on the brake repeatedly? You might try taking the hose off that goes to the intake manifold (the fat one on the lower left of the box IIRC), and then plugging it with your thumb. If your idle gets much better than before then you might have a vacuum leak in some other component that attaches to the vacuum box (brake booster, climate vacuum reservoir, etc).