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98 Windstar MIL code p300 misfire

Hi there,

I'm looking to solve my problem for not alot of money (aren't we all), I have done alot of research but I do need some insight.

My van started running poorly, but only when it rained. We replaced the spark plug wires as they were original. Next rain storm the same thing happened. The van sputtered on idle, backfired on acceleration but above idle was fine.

Eventually it threw a code, P0340 which is camshaft position sensor circuit. We replaced the sensor, code was cleared.

Next rain storm, same thing happened, except the MIL started flashing while it sputtered on idle and backfired on acceleration. Once it stopped raining and things dried out, the van ran like a top. The new code was P0300, Random misfire.

The common causes seem to be, spark plug wires, CMP, spark plugs, EGR, coil pack etc. The problem is this problem ONLY occurs in the rain, never any other time until today. It rained alot yesterday and the van was still running poorly today and has started backfiring on acceleration even at 100 km/h. My mechanic is leaning towards coil pack now, which makes sense to me.

Anyone ever had this problem only in the rain?

Information:

98 Windstar GL 3.8L 162,000 km's Replaced: Spark plug wires Camshaft position sensor
Reply to
goobers04
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Not much help to you but I had this problem on one of my first cars. It turned out to be a faulty (cracked) distributor cap and bad cover on the coil lead. When water spray collected enough mist on the distributor or coil it started shorting . Let everything dry out and no further problem.

Unless you can find an electrical connection exposed to the water that might be shorting to ground and seal it up I dunno.

Reply to
marks542004

If the van dries out and starts to run better get a plant sprayer bottle full of water and spray the coil pack and see if that provokes a missfire. Your "mechanic" should have known to do this the moment you mentioned the problem correlates with rain.

Don

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Reply to
Don

To add to the good responses so far, you may just have junk replacement wires. I wouldn't trust anything other than OEM or high quality replacements on a demanding ignition system like yours. Your mechanic is probably right about the coil, but I wouldn't rule out the wires just because they are new.

OBDII Fords are reluctant to set specific cylinder misfire codes and often only set a P0300 if the misfire duration on any specific cylinder is too intermittant. You could actually have one cylinder misfiring due to a wire, or two cylinders due to a companion coil inside the coilpack assembly. Water and an ignition scope could help in this diagnosis, or simply water and visual/audial inspection for spark arcing to ground anywhere around the coil or wires.

Given that even a Motorcraft brand coil pack is

Reply to
Comboverfish

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