P0302/p0305

[ronmancvu]

My mom's got a '00 Windstar with a 3.8.
She called me yesterday to say the check engine light was flashing and to see if I could come look at it. So, today, I go out there and scan the codes, and get a cylinder 2 and cylinder 5 misfire. I check for spark on those cylinders (which I confirmed is there) and then pulled the plugs. All 5 of the 6 were wet, and all of them were heavily worn. The gap had grown to >.090 and as best as I can tell they were the OEM plugs and wires. I put new Bosch platinums in and stuck in a new wire set.

I still had misfires on 2 and 5 when I took it for a test drive.

So, then I stuck in a new coil pack, plugged everything back in, and went for another drive.

And again, misfires.

So, I busted out the timing light and stuck it on all the wires. On bank 2 (cyl 4-6, the bank facing the front of the van) I was getting very rapid flashing, almost like the coil pack was sensing WOT. On bank 1 (cyl 1-3) I was getting very erratic strobing from the light, sometimes very fast pulsing and other times slow, steady pulsing like you'd expect to see at idle, and other times still erratic, seemingly random flashing. And yes, I had a good connection.

As soon as the afternoon storm ends, I'm going to pull the fuel rails and injectors and see what they look like. I don't have any vacuum leaks that I can tell, and the IMRC actuator rods have been disconnected from the runners at some point in the past.

Any other suggestions?

[wiswind]

The best plugs to use are the double platinum under the Motorcraft or Autolite names.
This is a plug that has the platinum enhancement on the center electrode AND the ground tab.
The Multi-pronged plugs that Bosch sell are not ideal for the windstar.
If you bought the single pronged plugs, they should work (if they are the correct one for the windstar as far as heat range, etc) but they may not wear evenly if the ground tab does not also have the platinum enhancement.
The spark plugs on the Windstar wear more on the center electrode on 1 bank of cylinders and more on the ground tab on the other bank of cylinders.
THIS is why spark plugs with the platinum enhancement on both locations is best, so that they wear more evenly.

It sounds like you hit the major players as far as a misfire code on your newer (1999 and newer) windstar.


The fuel injectors can also cause misfire, but not as common on newer windstars as it was on my older '96 windstar.
I found that Berryman's B12 Chemtool in the metal can was the only cleaner that seemed to clean the injectors up for me.

If the IMRC is not connected, the best thing is to fasten the rails in the CLOSED position as this will give you the best performance and fuel economy.
You will have reduced power at the higher RPMs, which is a small percentage of your vehicle operation.
If they are open at low RPM, starting, idle and normal operation will not be as good.
If one bank is open, and the other bank is closed, then your cylinders are operating at a unbalanced condition.

[ronmancvu]

Plugs themselves shouldn't affect the output of the coil itself, which is what the timing light is reading, but they are single-electrode platinum Bosch units. I'm not really sure why you focused so much on the plugs themselves considering the other detail in my post...

I pulled the upper intake and fuel rails today. Injectors were clean. I'm throwing on a new set of valve cover gaskets to fix those pretty significant leaks.

I cleaned the EGR passages (I assume that's what they are anyway) that come out in the intake runners as much as I could. They were pretty much completely blocked. I know the main passages leading into the valve are probably even worse, but the money for a new EGR valve and lower gasket set isn't in the cards right now. Plus it's never thrown an EGR code, so it's probably not THAT bad, right?

I'll be putting on a new cam sensor tomorrow, and if that doesn't fix it I don't know what else to look for.

[12Ounce]

I don't read that you have replaced the cables. ?

Would be high on my list ... maybe #1. And I would add protective flexible plastic conduit ... full length.

If that fails to correct the spark imbalance that you see, I would check continuity in the harness from coil pack all the way to the PCM module plug-in. I have found conductors worn in-two in the power train harness.

[ronmancvu]

After extensive diagnosis, we found the problem: a small, hairline crack in the #5 spark plug insulator. Van runs fine now.

[phil-l]

Thanks for following up.

I haven't had a spark plug fail in a long time - but your experience proves it can still happen!