major

I have replaced the distributor cap, ignition module, battery,alternator and plugs on my '87 944S, but it still misses, backfires and finally refuses to start while running in a hard rain for 10 minutes. It will crank after pulling to the side of the road, but will not fire. This rain senerio has happened 4 times and I need to get to the bottom of this. I intend to use RTV to seal the distributor cap and also install new wires. Is there anything else that when wet will cause misfires, backfires and finally a no running condition in the rain? Ignition coil? flywheel sensor? I give up!

The DareDevil

After the car dries up completely does it run like normal?

major

Yes. In about a day it will start and run again with no problems. Any thoughts?
Major

tazman

Check your spark plug wires. If the car is running right now start the car in a dark area with the hood open and see if there are any sparks jumping between the wires and the motor. It will be a lot worse once you get some moisture in there.

Legoland951

It should not do that if you have good caps, rotors, and wires. I have started the car after shooting it with high pressure water all over the engine bay of the car much worse than any heavy rain can do and have no problems with the car stalling out. If you spray water with a hose directly on the cap and rotor for a while it may have problems starting and sputter a little for a few minutes but most of the time rain water will not get up where the cap is in large quantities. You may want to check for leaks by the DME from the battery tray or your wind shield.

Frank Sinatra

Are you running a cone Air filter?

major

I do not have a cone air filter and there are no holes in the battery compartment. I'll check the wires really good and may have to spring for a new set. I have 215,000 mi on the car and the wire set on now is only the first set I have had to buy. I really had no problems with the original wires at 120,000 miles but changed them as a maintenance item. Boy those things are expensive. Thanks for the help

Major

qoncept944

Is the fusebox getting wet?

triscadek

I have the same problem, just not quite as bad yet and my mech. told me it was the wires.

Loses power, backfires under the hood and eventually dies.

adrial

I would vote for plug wirse as well if its been 100k miles since replacement as you described...

brrt50cal

My wires arc but I dont have that problem

major

I think I found the problem guys. I found a hole the size of a half dollar under the battery allowing water to get to the DME. The area of the DME was damp from this leakage. How is this best fixed? With fiberglass? Does the area have to be cleaned down to the bare metal in order for the glass to adhere properly? Thanks for all the help.

Major

triscadek

For any thing to properly adhere grind it down to the bare metal.