1998 V6 4.2, 2WD, 99,000 miles.

When I drive through deep puddles and when I go through a carwash that has the underbody spray, the truck begins to miss and does so for a few minutes, especially under load - its not too bad when just idling. The last couple of times the check engine light came on, though I have not had the code read yet.

Also, after a damp night, the truck will miss in the morning for a couple of minutes. It does this about 30% of the time after a really damp night.

Truck has been doing this for over a year, but the frequency is increasing.

Ford dealer had the truck for two days and could not find anything wrong. When this happens, there is no evidence of water on or near the spark plugs and wires, leading me to believe the cuprit is underneath the truck, in the front.

Any ideas?

Thanks,
Steve

 

Check the wiring around the O2 sensors. Water is probably getting in and either causing the engine to go full enrich or full lean.

I would seal them with some type of high temp RTV.

 

put some dielectric grease in your plug boots, i bet that is your problem.

 

Sounds like the plug wires need to be changed.
Look at them, the plug boots are most likly split open.

 

Go to Auto Zone and have them pull the codes "free" and see what cylinder(s) are coming up as misfire? That will likely cut your posiabilties in 1/2. Take a pen and paper right down the codes then come back here and post them. I'm thinking if not Plug wires then one of the ICM's. A hairline crack will let it draw moisture and no one could likely see it. Most likely in your ignition some where but the O2 suggestion is a good idea too.

 

I went to Autozone this moring and they told me the code was for "multiple cylinder misfire". I don't have any more detailed information other that this.

What is "ICM"?

As for the O2 sensors, I looked last night after the truck started missing, after driving through a large puddle, and there was no water around the sensors, nor was there any around the plugs or wires.

Since the wires appear to be dry, does that rule them out? Could there be excessive moister from the water hitting hot parts of the engine creating steam that could affect a bad wire or plug? Of course, I did not see any arcing in the dark.

I'm not too mechanical, just know some basics. But if the code says the cylinders are misfiring, and the truck only misses at times when water/moisture is invovled, I wouldn't think there are too many things that could go wrong other than wires, plugs, the coil pack, and the 02 sensors. But most of these items are near the mid to top area of the engine, and the water from the deep puddles, and the car wash, seem to be splashing quite low on the engine.

About five weeks ago I sprayed the wires and coil pack with STP silicone spray, so that didn't appear to help.

Tomorrow I will try to thoroughly inspect the 02 and spark plug wires. Any other suggestion are greatly appreciated.

Thanks,
Steve

 

ICM = Ignition Contol Module

Did 98 have individual Coil Packs? I thought that they had 2 ICM's one for each bank then? I was hoping that the codes would give cyl. #'s so would tell which ICM it might be IF it is an ICM. IF it has ICM's. I would first replace the Spark Plug Wires and use Dielectric Grease, see what happens. If it were me anyway, it never hurts to have new SP Wires anytime.

 

My 97 had 2 ICMs, one in front of each bank.

 

That will prevent an outside air sample from getting to the HEGO as well. Don't do that.

 

Does the sampling air enter though the same hole that the wire passes thorugh? Not famliar with the year.

Only reason I suggest this was because I had the exact same problem. My wife said the car died when going through a puddle on the right. Naturally I thought she was carzy. Untill I was driving her car and it did it to me. That was what it turned out to be.

 

On the sensor itself, yes.

 

Well Yup I guess that would be the sensible place for it. I don't think it gets sampling air through the very same holes the wires passes through the rubber grommets. Guess it could though.


Any way, this probably does not apply either. Had a V6 Windstar that would run like on 4 cylinders. Changed the IC pack and it ran fine......then a few days later it did it again. Codes called for two cylinders missing and they were not sister cylinders. Put some dielectric grease on the plug of the IC pack and it has not come back. Not sure how water or moisture was getting to the plug. The pack is high on the engine and in the back. Oh well just a thought.

 

Things don;t have to be dripping. Had an old chrysler in my youth with a slant 6. The wires were so bad that a humid day would do it. Let alone a rain. That was before I knew what money was. After every rain I would go out open the hood and spray the wires down with WD40 just to get it to start.

Good luck.

 

^^^ LOL ^^^

I think most all of us have had those vehicles... I hated them at the time but because of having them I learned how to work on vehicles. Since I had to work on them 8 times out of 10 to make them get me where I was trying to go. Of coars in my youth there nothing that was very important to get there on time anyway.

 

Amen, Brother Matt, Amen!