Sounds like you have a good plan to follow. There are 3 basic things that can cause a misfire.

Fuel system, this will mainly be several cylinders unless a injector.

Ignition system, ICM, coil, plug wires, spark plugs.

Mechanical problem. Compression test.

i had the same problem in cylinder 4 changed injector fixed problem for good my code was p0304

Drove home last night with no misfires.

Changed coil pack 1-4 with coil pack 5-2. The secondaries (top) on 1-4 measured 6.55 KOhms, and 5-2 measured 6.37 KOhms. The primaries on 1-4 measured 6.05 KOhms, and 5-2 measured 0.8 KOhms. I did not observe any corrosion on the ICM connectors to the two coil packs, but I wire brushed them and put dielelectric grease on them.

No misfires on the drive into work this morning, which includes expressway driving at 75 MPH and the long climb up and over the Ambassador Bridge.

Based on Dan'* writeup on testing coils, it would look like 1-4 is out of expected range on the primaries (6.05 versus expected 0.6 to 0.8 KOhms) but I was not getting misfires on those cylinders. My electrical meter was acting up a little last night, so I will put a fresh battery into it and retest all three coil packs tonight.

This is starting to look like an injector problem. Dan, you said yesterday there is only one fuel rail, but it looks to me like there are two, one foward of the supercharger for the 1-3-5 cylinders, and one rear for the 2-4-6 cylinders. Did you mean one fuel rail per bank?

I can't pull fuel rails until the weekend, and I don't want to pull them anyway until I get another misfire to see if the problem followed the coil pack, so all I will do (until I get a misfire) is pull all three coil packs tonight and test the primaries and secondaries.

Any comments or suggestions?

Roy

Sawgunner, when you changed your #4 injector, where did you buy the new one and what was the cost? Did you try running a cleaner (Seafoam, fuel injector cleaner, or whatever) through to see if it fixed the problem before you replaced the injector?

Roy

As far as injectors, rather than relieving fuel pressure through the valve, I've done this:

1) Turn car to on position (do not start engine), wait 10 seconds then turn key off. This pressurizes the fuel system.
2) Remove fuel pump fuse.
3) Start car and run it until it dies.

I've only messed with fuel injectors a couple of times but that has worked for me. A couple of warnings:

- clean intake manifold near injectors before starting removal process.
- As you remove injectors, verify no O rings are missing then immediately plug the holes to insure nothing drops in the cylinders.
- lightly lube O rings with petroleum jelly before reassembly

No misfires on the commute home last night, or in to work this morning. That makes 3 commutes so far without a misfire. Either the problem is waiting to pounce on me when I least expect it, cleaning the coil pack contacts has fixed the problem (I didn't see corrosion, but there might have been a bad contact), or the gods of fuel, wind and fire have smiled on me.

My guess is the problem will pop up again, and probaby at the worst time.

On the assumption I don't get any misfires tonight on the way home, I can change the fuel sender this weekend. If I don't get any misfires for the next week, I will throw some Sea Foam into the gas tank to clean the injectors.

I will post an update if I get a misfire, or in one week if I don't have a reoccurance.

Roy

Loose/bad connection maybe.

Eother way,,,,,, woo hoo !!!!

As expected, congratulations were premature. Went out for lunch today, and when I started up to come back to the office, the car was missing. (Actually, the car wasn't missing, it was right where I parked it) Drove about a mile and problem went away. Got back to the office and my scan tool pulled P0305. Therefore, the problem is still with cylinder #5, and did not follow the coil pack.

Looks like its into the injectors this weekend.

Roy

One thing I like to do is use my mechanic'* stethescope (Sears or parts place) to listen to the injectors. That gives you a good idea of what is going on...expecially if one is silent.

BTW check the connector to the injector before pulling the injector. You can also test the connector with a multimeter or a 194 bulb (turn signal) with the leads straightened out.

Ever been dead on the side of the road? I have!

I thought about popping into the Napa servce center across the street from work to have them check out the injector, but the problem is the misfire comes and goes. Unless it is actually misfiring at the time, listening to or testing the injector may not yield anything.

I will definitely check the wires and connections. How do you check an injector with a multimeter?

Roy