96 Crown Vic #4 misfire ???

I'm getting a #4 misfire code, but the car runs fine and the spark plug looks perfect. The plug is new, the wires are fairly new. What else could be causing this code. I have another coil pack to try, but I doubt that is it. Leaning towards an intermittent bad wire on #4. Looking for other ideas.

Is fuel injector supplying proper amount of fuel? A lean condition in the cylinder will cause it to misfire.

I suppose that injector could be messing up. I don't know of a good way to test them. It could also be mis fireing on the old gas too. I pumped the tank out and poured 10 gal of fresh in but still has a varnish smell at the rail. Probably will have to run a few tanks of gas through it to clear out the sludge.

You can roll the fuel injector just like a plug, wire, cop, or coil!
We usually take bad injectors for a good cleaning at a local diesel shop for a micro bath, blow out, and the flow rate tested.

If the problem doesn't roll, check the compression on that cylinder.

Lay the coil on its side and put in a good plug ground the plug if you have good spark. Check the compression on this cylinder if its satisfactory put in a good used injector or swap injectors with another cylinder. If the misfire changes cylinders you have found the problem.

This car still has the old style duel coil packs not the individual ones. I think Ford switched designs in 97 or 98. I really doubt it's coil pack related but I have another one, and they are easy to swap. So will try that, and I will try switching the #4 wire and see if that changes anything. I also have another injector to try. I'll save that to last if the other two items above have no change. The injector isn't too hard to swap out, but not super easy either. The strange thing is that the #4 spark plug looks great not to rich, not to lean, not fouled. It looks like the text book example of what a proper firing spark plug would look like. I have already checked the compression and it's good. Since the car runs great, I can't get too concerned. The check engine light is just annoying as hell. I really think the engine is having a hard time burning the crappy old gas. I will also top off the tank with some fresh and see what happens.

Ok I am getting an intermittent misfire. It started out with #3 then went to #4 back to 3 and now reads p300 multiple random misfire. All the spark plugs are good I have checked them again and again. Compression is good I have checked that. I have switched coil packs a bunch of times. I am going to change the entire set of plug wires next and see if that helps.

How much of this could be caused by old cruddy gas? I have about 15 gal of fresh in the tank. I think I have enough fresh gas in the tank for the car to run good.

This almost seems like an ignition module going bad to me. I have asked around on the forum several times about an ignition module on the 96 model. No one seems to know. According to my Hollander interchange it has one, but they don't always have the facts. I can't see any modules on this car. It is not on the drivers side fender well like the 95 model. Can any tell me for sure if the the 96 has one or not ?

I couldn't find an ignition module in my products research manual. As 3 and 4 plugs are fired from the right and left coil. Ohm your plug wires for these two cylinders. Wiggle the wires as usually they come loose on the plug end. Cut off about two or three inches and re crimp if bad. Use a long screw driver and listen to the problem cylinders injectors. Use your ohm meter and ohm injectors on some of the injectors. Look for a couple out of range.
Otherwise swap to good used injectors in place of the two in cylinder 3 and 4.
This is a common problem on this year vehicle.

Right on. Since 3 and 4 run off separate coil packs, I really doubt they could be the problem. To bad the mis keeps moving around. I was suspecting the #4 injector, but now #4 is fine and going to the random misfire code. If the mis would just stay put, I could pin point it. I want to try the wires before I do anything else. Then I will do what you said and swap the #3 and #4 injector and see what happens. This car has the old fat style metal body injectors. I have several other sets of injectors from motors that ran good to try. Man I tell you this car ran 100% perfect when I got it, but that siting around just kills them. Thanks for the input Richard.

A set of these would be handy in your business.
http://www.autopart.com/tools/toolsmain/tool/T_3401.htm

I Think I fixed the miss in my car. I changed plug wires to an good old set I had laying around. They are apparently better than the newer set I had on the car. I had the plug wires on and off a million times trying to fix some other things, they must have gotten broken in the process. The car seems to run perfect with no miss. I will do some more test driving tomorrow. and post the results.

Like a tic on a hound dog, Silicone Spark plug wires do brake down!
Lincoln service is $500 for spark plug wire replacement, I buy mine at Auto Zone.

I Think I fixed the miss in my car. I changed plug wires to an good old set I had laying around. They are apparently better than the newer set I had on the car. I had the plug wires on and off a million times trying to fix some other things, they must have gotten broken in the process. The car seems to run perfect with no miss. I will do some more test driving tomorrow. and post the results.
I'm surprised you didn't have minor backfire with this problem.

Come to think of it I did hear some popping noises like mini back fires once and a while.

The car is running perfect now, spark plug wires were last piece of the 1000 piece jig saw puzzle. Thanks to all for the input on this one.

Moving on to the next project soon, a 98 Lincoln Town Car that won't start. You bet I'll look at those rocker arms first thing on that one to see if some are jumped off like this Crown Vic.