Skip the auto shop - Our mechanics make house calls

Q: Engine keeps misfiring on humid days

asked by on

My car has engine issues only when the weather is humid. Then, it would start misfiring. I had the distributor cap replaced along with the rotor and plug wires as well. The car runs smoothly when the weather is warm and dry. However, despite these repairs, the engine keeps misfiring on very humid days. What should I do?

The humidity in the air will also affect the air pressure around your vehicle. When air pressure is affected, engine vacuum is also affected. The engine’s positive crankcase ventilation system relies on engine vacuum to function properly. If the engine vacuum is not sufficient, the PCV system may not work properly and allow the engine oil to reach the air filter. If the engine oil reaches the air filter, this can saturate the air filter and cause oil to be drawn into the throttle body with intake air. If this happens, the engine will burn oil and therefore have a misfire. I would recommend having your air filter and PCV system checked out to determine if any issues are present and start from there. A qualified mechanic, such as one from YourMechanic, can perform an engine misfiring diagnosis to determine how to proceed with a repair.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
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

Get a quote

What others are asking

Q: I've replaced everything from tie rods, upper and lower ball joints, the whole cv axle including cv joints and boots, and I'm stil

Hello, thank you for writing in. The noise you are hearing may be a result of a wheel bearing or a shock issue. There are several tests that can be done while the vehicle is parked, and some while it...

Q: Should i buy this Acura RSX Type S with a idle control valve that need to be fix?

Hello. This is a very low price for an otherwise great car. I would recommend having an expert mechanic inspect the car prior to the purchase to check for other potential issues. Although, the two issues you have described are...

Q: I have a 1999 mercury villager. It has been overheating. Can I take it to autozone to have them check the codes to find out why?

There is a code for engine over temperature that may be stored in your vehicle's powertrain control module. Most auto parts stores will pull the codes for you and let you know what they are. YourMechanic also offers [check engine...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...