When I was changing my spark plugs I managed to wreck one of the wires. I had forgotten the correct order of the cylinders and transposed two of them so the car ran like crap. I spent all day taking the coil off and putting it on... :lol:

Well, what I am saying is check out the wires. They may have been damaged during the work.

 

My car wouldn't stay running right after I removed the dash to replace my heater core. I found out I had left one of the bolts loose on the 3 large bundles of wires under the dash. OOPS! Check and make sure those and any under the hood are ok as well.

 

Egr valve hanging open can cause this, also most of the egr ports in the lower intake could be clogged and sending all of the exhaust into a couple of cylinders instead of all 6. This is common to windstars and 4.2 pick-up trucks.
Also check to see if the ground strap from the engine to the body is hooked up, this will cause all kinds of weird problems if it is unhooked or loose

 

I dropped by AutoZone today, they hooked it up and the code that came out is "Misfire cylinder 4", P03404 or something like that. Cylinder 4 is the one nearest the P/S pump, I've checked that wire before but didnt pull the plug, will do that tomorrow, as well as pull the air box and maybe the cowl so I can get to the DIS module and make sure the wire is plugged in good.

I guess its a possibility the wire got cut or pinched when they moved the engine around to get the trans out and back in (on the rear of the block its the lowest wire leading to the DIS module, not much higher than the top of the trans). Oh well, "lifetime" warranty at AutoZone on the wires, hope they accept.

 

Last week I pulled out the #4 spark plug, it looked like the center electrode has grown "out" of the ceramic and towards the top electrode :blink: so the gap was less than .040. I put in a new Bosch Platinum to match the rest and checked the gaps on the other 2 front plugs, those were fine.

My dad drove it for around 100 miles with no problems, then the misfiring started again, he thinks it could be the injector. We'll have to see, gonna have to pull the whole top intake to get to it. :angry:

 

Check the wires, if you haven't done that yet, and the coil pack.

There was another member who had a similar problem. Here and here. It turned out his PCM was bad.

That's a really nice avatar you have there. I... like it...

 

I havent gotten around to the coil pack, on the Windstar you have to remove the wiper assembly and the rest of the cowl, along with the airbox in order to have some decent room back there. :angry: :lol2:

Thanks for the suggestion about the PCM, I looked over those other threads, actually found them a while back but didnt keep up. I forgot to post, or think about it, but the exhaust does have a very gassy smell when the engine is misfiring, so I can rule out the #4 injector. That leaves the ignition system and PCM.

The PCM idea is a good one, as the misfiring only happens randomly, so a software glitch might be it. I might as well check the dealer and see how much it would cost for a full diag. before I get another PCM.

My avatar, I put it up over 2 years ago, we had this section on the forum for political/heated arguments, and somebody called alcohol evil. Well I wont stand for that! :angry: :lol2: :lol2: :banana: Bottoms up! :chili:

 

Oh, and if they throw in a compression test (like for that other member) for under $100 it'd be well worth it. This 3.8 has 117K and runs great except for the misfiring, but I'd like to make sure head gaskets arent creeping up on us. <_<

 

you can get a compression tester for 20 bucks just about anywhere...

It sounds to me like you have a bad wire. I had a set of cheap wires, my car never idled right. One night at a car wash the engine got wet and began to misfire. It went away 5 minutes later...then a week later I was at an intersection and the car got real rough and the check engine light started flashing. I heard it arking when I popped the hood. I closely inspected it and found 2 small cracks that were only noticable if I bent the boot in half...

Autolite Professional wires are nice...

 

98 Windstars dont have the headgasket problem.
They like to blow lower intake gaskets, have EGR ports clog in the lower intake and have bad coilpacks.
My guess is one or more of the 3 is your problem.
Does your coolant overflow bottle have black sludge in it? That is a sign of oil contamination in the cooling system from a blown Intake or timing cover gasket.
#4 cylinder misfire is a common one for a blown lower intake gasket, the gaskets like to rot out on the end cylinders.

 

I just want to point out that the PCM is one of the more reliable parts of the car and it is much more likely that there is some other problem. If there is something wrong with it, it wouldn't be a software problem in this case. Instead it would probably be a failure of the output circuit that drives the ignition coil/fuel injector/whatever.

OMG cold ones...

 

Tmonster, not sure what brand the wires are, but they cost around $30 at AutoZone, I still have the receipt for them.

Punisher, they fixed the hg's on the 98's? That's awesome. :banana: Probably explains why this hot-rod hasnt given us any problems yet :lol2:

Dont remember seeing any black sludge, but I'll check it again, and no oil residue in the radiator either. Since its been new, its leaked a little oil (or gas most likely) around the lower intake and it gets cruddy. Whats the best/easiest way to test this without pulling the intake. This doesnt look like a fun intake to remove. :lol2: I'll try to get this resolved this weekend or early next week before I leave for Europe for a month.

Holedigger, got a heineken with me right now. B) And I was doubting this being a PCM problem, but seeing as how the engine was either pulled or most of the wiring disconnected when they rebuilt the trans, its easy to bend a pin putting the harness back on.

BTW I'm going tomorrow to pick up a header panel and corner lights for the van, already got a right fender. Long story short, dumbass hick in a GMC decided to switch lanes while me and my dad were in the left turn lane, right corner smacked his door. :angry: Its been a few weeks but it's getting a facelift this weekend!! :lol2:

 

Hey ya'll, just got back a week ago from Romania and now I'm working on the van again. <_< Still misfiring as usual in #4 cylinder.

Changed #4 spark plug wire - same misfiring. :angry:
Changed entire coil pack - engine runs the same, slight shaking at idle, will do a longer road test to see if the misfire comes back <_<
Might be replacing the PCM, found one with the same model code for $75 about an hour away, dad's going to be around there monday anyway so if the coil pack changes nothing, I'll replace the PCM.

Interestingly, I still have the old 99 SE Vulcan PCM and today on a hunch I swapped it in. :lol2: :banana: Started the van and the enginge ran, surprisingly, better! :woot: Even with the difference codes and programming, the Essex was running slightly smoother than with the old Vulcan PCM. O/D light was flashing and the idle rpms were higher, took it on the street for a little bit and acceleration was smoother but the tranny wasnt agreeing with the Taurus PCM codes so I didnt push it.

So I'm gonna go with the PCM on this one, I'll know more once I drive it a little bit tonight and maybe with the new PCM on Monday. Cross your fingers!!! I dont want to replace any intake gaskets!!!! :angry: :lol2:

 

So I drove it 20 miles and it started misfiring again, picking up the new PCM tomorrow and see if it fixes it, if not I'll have to wait a while before I have time to tear down the intake. Bout to get back to hittin the books!

 

Mishnah

I was the one of the other members that has had the same cronic random misfire. Original took it to the dealer and the swear it was the PCM. $800 later, still misfiring. They also said with the complete diagnostics and compression test, that I had a possible blown head gasket. As compression was down on that cylinder and adjacent cylinder.

I am about to pull that cylinder head this week. Not a pretty job, but prior to doing so, I will be redoing the compression test to make sure. Your symptons are the same, and through my process, I have gone back to basics. Spark, fuel, compression. I changed all the plugs, wires, and coil pack. So I have to now look at compression.

Get the compression test done to confirm you are getting compression.

 

Thanks for the help! It does have 120k miles so maybe that time has come. Didnt have time to get that PCM today but I'll ask my neighbor (former salvage yard owner :woot: ) if he has a compression tester. If #4 is low, it might have to wait till december when I'm on vacation to get fixed, me and my dad are great gearheads so we'll try to save that $400 or so. :lol2:

 

Bought a compression tester today, all 3 front cylinders are getting 180 psi cold, and hot: #4 200, #5 195, #6 200. So I guess that pretty much rules out a head gasket, no major drops there. <_< If the HG's are good, I'm very happy! B)

So now its narrowed down to PCM or lower intake gaskets.