99 XLT, misfiring, CEL flashing, possibly fixed due to rust on coil pack?

[mikepier]

I had a wierd issue pop up last night on my way home from work.

I noticed my truck running rough on the expressway. Next thing I know, my Check engine light was flashing. When I pulled into my driveway, I could tell it was not running on all cylinders. So I shut the truck off, let the truck sit, then came out about an hour later. Started it up, and ran fine for approx 10 minutes, then started to act up again.

Then I came across this post of the coil pack having rust on the bottom of it possibly causing issues.
http://www.explorerforum.com/forums/showthread.php?t=373394&highlight=coil+pack+rust

I figured what the heck, let me try it. So this morning I took of the coil pack and there was rust. I cleaned it up, put it back. While I was at it, I ohmed out my coil pack to make sure it was good, and it was.

I started the truck, took it to work, and no more issues. Also went to Auto Zone to pull the stored codes and it said PO171 ( Bank 1 rich/lean condition) and PO302 ( cylinder 2 misfire).

Could the coil pack rust have caused this? Or was it just a coincidence that I moved it?

 

[mikepier]

OK, that obviously did not fix it as I'm still having problems. This is reallly wierd. When I start it when its cold, its fine. But after about 10 minutes, it starts to misfire.

I disconnected the ignition wire for cylinder #2 at the coil pack. And there was no difference in the engine running. But I did see spark jump from the coil to the wire. So does that mean the coil is good, and something else downstream?

I suspect maybe a bad spark plug or bad injector. But I'm stumped why it runs good cold, then acts up when it warms up. So is there a good way to test the injector? It looks like a PITA to get to it.

 

[mikepier]

OK, that obviously did not fix it as I'm still having problems. This is reallly wierd. When I start it when its cold, its fine. But after about 10 minutes, it starts to misfire.

I disconnected the ignition wire for cylinder [URL=http://www.explorerforum.com/forums/usertag.php?do=list&action=hash&hash=2]#2 [/URL] at the coil pack. And there was no difference in the engine running. But I did see spark jump from the coil to the wire. So does that mean the coil is good, and something else downstream?

I suspect maybe a bad spark plug or bad injector. But I'm stumped why it runs good cold, then acts up when it warms up. So is there a good way to test the injector? It looks like a PITA to get to it.

Well I took a chance and bought a new coil, and of course, that did not fix the problem.

So I took apart the upper manifold to get to the fuel rail. I check the #2 cylinder injector with an ohmmeter, and sure enough, the coil was open. I've never seen an injector go bad before.
So now I'm waiting till the morning to get a set of 6 injectors. Might as well do all of them at once.

 

[Flash]

I've never seen an injector go bad before.

I have, twice.

 

[Runnin'OnEmpty]

I recently had an injector go bad. It was the first for me
too. Might have something to do with today's ethanol
gas...?

 

[mikepier]

My failure was electrical. I tested the injector, and it read open across the coil.
So I went on a wild goose chase in my town yesterday morning looking for injectors. Auto Zone and Advanced had none. I managed to find a set at Parts Authority, but all they had available was "GB Remanufactured" injectors. They looked identical to my old injectors.

So now I had to find the o-ring adaptors that fit into the intake manifold with the injectors because mine were brittle and broken. After a few phone calls to dealers, one of them about 15 miles away had a set of 6. So I went out of my way to get them.

It was a real pain getting to the fuel rail. I had to remove the upper manifold, and a few other hoses, electrical connections. I had to buy a special Torx socket. The 2 back screws are a pain to get to. I also lost one of them when it fell behind the engine. My truck is 16 years old, all of the rubber hoses felt hard and brittle, I felt any tough movement would break something, so I was careful. I only replaced the passengers side. injectors. I did not do the drivers side. I felt leave well enough alone before I break something and make things worse. If one of the injectors fail in the future, I have the parts now and I know how to change them.

Now that I have a new coil, I am ordering a new set of plugs and wires from Rock Auto. Last time I changed them was in 2007.

 

[drdoom]

If you are referring to the back intake screws, on some models the PCM harness needs to be disconnected at the firewall to improve access to those back screws.

 

[mikepier]

Exactly that's what I needed to do, disconnect the PCM harness.