Rough running after rain - even if not driven in rain.

[fix_wifes_camry]

Gentlemen,

My 1990 Camry wagon, 2-litre: Whe n it rains, it runs real rough until the engine warms up thoroughly.

But here's the real mystery: If it happened when driving in the rain, kicking water up onto the electrical, you'd say right away bad wires or something associated with being wet. But even if the motor is bone dry when I park it in the driveway, if it rains, it will be hard to start and run rough even though no water could possibly have speen splashed up into the motor compartment.

And here's the twist: So last night it rained after having driven the car hot and dry the day before. This morning before even starting it I pop the hood - the engine is wet!! Now, it's an old dirty engine with oil and grease here there and everywhere. And anywhere that's "dirty" is soaking wet, with the water beading up on the oil/grease. This includes the rubber boots over some electrical. What the heck? Grease that's both hydrophbic and hydrophyllic?

One such boot in particular I'm suspicious of is on the front right end of the head, just below the valve cover, near the distributor cap. A big fat rubber boot witha single skinny little wire coming out of it and going I don't know where. The boot is covered in grease and soaking wet. Is this something critical like the cam shaft position sensor and it's misbehaving when the boot is wet??

Last summer I replaced the distributor cap and all the spark plug wires to address this problem, and it appeared improved for a while. Then this summer it's gotten worse.

Any bright ideas would be welcome.

Thanks

[Mike Gerber]

You may have a bad coil inside the distributor cap, given that the cap wires and wires are relatively new. First I would replace the distributor rotor, if you didn't do that when the cap and wires were replaced. This probably isn't the cause, but it will eliminate it as a possibility. The coil is a known trouble area on 2 liter 3SFE engines. The coil developes a hairline crack and shorts itself to ground on any metal inside the distributor when the air is wet/damp. You can test the coil with the specs from any manual and a DVM. There is a generation 2 Toyota factory service manual stickied at the top of The General Camry Forum that is available for free downloading. It will have the specs. The test may or may not show the problem. The fix is to replace the coil. They are around $40-$50 for an aftermarket coil.

Mike

[fix_wifes_camry]

Now that's some highly valuable info - tendency to hairline cracks causing shorts in damp weather. Thanks a bunch.

Still wondering about the greasy areas attracting moisture (hydrophyllic) and then beading it up (hydrophobic). Maybe some mysteries of the universe are better left unsolved!

[Doctor J]

Is the rubber boot 1 inch in dia,2 inch long and has a single wire going to the harness?
Also make sure that the air cleaner element pleads are not collapsed.
If the boot same as I described, pull it out to expose the oil pressure switch.If it is leaking, it needs to be changed.
The older switch design with screw in the middle is more leak resistant then one with round flat rivet in the center