Q: Unable to start after it rains or misfires until the engine heats up in high moisture conditions

asked by on November 03, 2016

After a heavy rain the van will not start it will turn over but not fire. If there is a heavy dew in the morning or a fog situation it misfires until the engine heats up after that it runs fine. I thought the hood gasket may be worn out allowing water in the engine compartment so I replaced it and the problem persisted. I cleaned the Mass Flow Valve with the spray they make for that and that didn't do it either. Is there another sensor that I should be looking at?

My car has 115000 miles.
My car has an automatic transmission.

Hey there. This misfire no-start in wet or damp weather is going to be caused by the ignition system of the engine. In order to isolate the cause you can remove the inside engine cover and then start the van.

Watch the ignition wires, coil, and coil wire for arching while using a spray bottle with water to spray a fine mist of water on the ignition system in small areas at a time to find the cause of the engine misfire and you will get a misfire or stall when the spray then causes a miss. You most likely will have an ignition coil and plug wires that are arching to ground. After the cause is found, then I would recommend replacing the distributor cap and rotor, plugs and plug wires and the the ignition coil. This should repair the problem for you and the engine will run better altogether with a fresh tune-up.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

What does "battery saver active" mean?

Hello. Your message indicates that the electrical system voltage has fallen to 11.7 volts. This is rather low for a modern car with the engine running - normal voltage should be about 13.0 volts. Perhaps your new alternator has a...

How do I open and close the sunshade?

The sunshade feature allows you to block incoming light from the sun roof. The sunshade can only be operated manually. To open the sunshade, slide it open. To close the sunshade, slide it closed. The sunshade can only be closed...

service ESC and traction control message and power steering out.

This will require the use of a scanner that can read codes and data form the control module. There may be an electrical issue and not a component issue. A fuse that operates the system could be open and not...

My car has been making a rattle noise.

The heat shield is designed to keep the engine at a specific temperature. I recommend leaving the heat shield on but fixing it to where it does not vibrate. Look for any cracks or broken bolts to see if the...

the oil pan drain plug head is rounded off to remove the plug are the threads clockwise or counter clouckwise?

To remove the drain plug, turn the plug counter-clockwise. You may need to use a "bolt-out" type socket to grip what remains of the head. In the event that the internal (in pan) threads are damaged and you need a...

I have a 2012 Dodge Charger R/T AWD and I have check engine light issues

Hello, thank you for writing in. The long list of potential issues that cause hard-starts and misfires is profound. Without knowing exactly what diagnostic codes the dealership was pulling from the check engine light, it is impossible to narrow down...

Random misfire on cylinder one - 2000 Chevrolet Corvette

Hello. Random misfires can be caused by a few different things. If the coil packs are all good then it may be possible that the issue is not related to the ignition system. A few other things that can cause...

Will a 1996 transmission from a tahoe fit a 1999 chevy tahoe?

Both of these vehicles use the 4L60E/m30 transmissions. The only thing that may concern me is the 4 years difference may have changes in the wire connections between the two transmissions. I would recommend checking the two wire connections between...

My truck has a fuel smell in the exhaust and a horrible idle

I would suggest checking the idle air control valve to be sure it has a proper connection and is not dirty. As you may know, this reads the air intake into the fuel injection system as it is mixed with...

Related articles

The Best Used Cars to Buy If Safety is #1
Maybe Maybe you’re a parent buying the first car for your teenager, or perhaps you’re a new parent and the safety of your little one is of the utmost importance. Or perhaps you're a safety-minded individual looking to make a...
How Are Car Sensors Protected From Heat and Debris?
Reliable car performance depends on sensors to collect and relay data. Some car sensors can be cleaned to make them work reliably again.
Symptoms of a Bad or Failing Speedometer Sensor
Common signs include the speedometer not working, cruise control not engaging, Check Engine Light coming on, and loss of power.