1997 Windstar GL 3.8L Intermittent Misfire on 2

[bdrumr56]

Hello all! New poster today...

I have a new (to me) '97 Windstar with 128K +. C.E.L. is on and intermittently flashing. The code reads P0302 (Cylinder 2 Mis-fire). No other codes are set. Have cleared them many times and gone through multiple drive cycles.

Description of issue: After clearing the codes, and indeed upon each startup, the car starts and idles smoothly without hesitation or issue. It pulls away from parked position without issue. Appears to accelerate just fine. In stop-and-go traffic or directly onto the highway it seems to run smoothly without problem. After a period of time (I don't believe it to be consistent), it will start to misfire and the C.E.L. will be set. If it is still misfiring, the light will flash.

Here's the weird part...when stopping at a traffic light or just continuing to drive on the highway, the misfire will resolve and the car will run smoothly again. The C.E.L., trailing the condition by a bit, will go to solid from flashing and will remain that way until a little farther down the road. The misfire never seems to be more than one cylinder and the trouble code seems to bear that out. Just idling, the car will return to smooth operation and it seems to have smooth acceleration. In other words, the misfire seems to go away under acceleration.

What I've done: I've replaced plugs and wires. No change. Replaced Coil pack. No change.

Next steps: Next steps seem to be looking to fuel or air. My concern with that approach is the occasional nature of the problem. Compression problems would be consistent across the board, right? That cylinder would always be a problem. Same thing for fuel (fuel pump and/or filter). All cylinders would have the problem and it would have issues starting. OK, next thing--injector. Would an injector have spotty performance like this? Help me out here... Also, could it be related to the EGR ports on the intake on this vintage Windstar? (Once again, is an intermittent problem consistent?) Finally, since the primary circuit for spark is controlled by a PCM pin setting a ground for each cylinder, could the PCM, or wiring, be the culprit?

Sorry for the long post!! Any help would be much appreciated.

(BTW, I have not yet done the Berryman's Chemtool. I will start that today...)

[scubacat]

Is that the only code you're getting?

Pull the upper manifold (plastic part) and make sure the EGR ports are clear. Those get clogged and cause that exact symptom.

Do you see any oil in the coolant overflow bottle? Also check the little white bushings on the IMRC rods as they often disintegrate and break off (although that'll usually set a different code as well, check them regardless since it's easy while you have the cover off.)

[bdrumr56]

Yes, the only code is the misfire. No "lean" codes, EGR, MAF, Crank or cam position codes. I will indeed do the clean-up of the intake manifold and EGR ports when I'm up to screwing with removing the cowling again... Thanks, Bdrumr

[scubacat]

Cool, please post an update when you figure it out. My money is on EGR ports, though, especially with new plugs, wires, and coil. VERY common - happens to all longterm Windstar owners.

[tomj76]

I agree with scubcat. I had a similar problem, which several third party mechanics could not diagnose. I took it to Ford & $400 later they had cleaned the EGR ports, replaced the upper manifold gaskets and fixed the problem. Gaskets were $10 and the cleaner and labor were $390, so the next time(s) it showed the same symptoms I did it myself. It's not too hard once you work your way through it once.

Much advice has been given here on this forum for how to do it.

[bdrumr56]

Thanks TomJ and ScubaCat. I think I'll be doing this job this week. I'll post to let you know the results. Once again, appreciate the help.

[tomj76]

When you do this, be careful while removing any vacuum lines, particularly the smaller plastic ones. It's possible to break them if you manhandle them, and they are difficult to replace.