Q: Car is misfiring

asked by on

My local Mazda dealership mechanics couldn't figure this problem out. I've been experiencing misfires on the #3 cylinder for a couple years now. While the car was still under warranty, they would just replace spark plugs and coils, then the car would be fine for a time. I think the last year it was under warranty, I had it in 4 times for the exact same issue. They eventually swapped the #3 coil and plug with one of the other 3 in the car and the misfires continued on #3. Then they replaced the air intake, but it still happened again. The check engine light came on and #3 cylinder misfired again. While working on the car with a friend, we pulled the power harness from the front of the #3 COP, and then he realized he didn't have the tools he needed, so we plugged it back in. I started the car to go home, and the previous sputtering/misfires had gone away. Later that day, my check engine light also turned off. So, it turns out that every time Mazda was replacing spark plugs and coils, the only thing that was really fixing the problem was them unplugging the power from the #3 COP, and then plugging it back in again. Since then, misfires would happen every about 2 to 3 times a year. I unplug the power from the #3 COP and it would fix it every time. I've tried just moving the wires near the plastic connector a bit when this happens, just in case something was loose, but the only thing that ever seemed to "fix" it was to unplug and plug it back in again. So, that brings me to this week. I've had misfires the last several days in a row, and my previous workaround is not working anymore. Is this something I can fix myself?

It sounds to me like you have a wire connector issue with the ignition coil pins. The male and female sides fit too loose and only make partial contact. After driving a while a small amount of corrosion forms in the connection and causes the misfire. As soon as you disconnect and reconnect it the connection was made again so it would work for a while. The coil may have failed due to excessive resistance from the corrosion in the connector, and this is most likely what has happened now. I suggest you have the vehicle scanned again. If the failure was #3, then replace the coil and connector. You should also try and put stabilant 22 in all the coil connectors before reconnecting them. The stabilant 22 will stop any corrosion and help keep a full connection. A certified mechanic from YourMechanic can inspect your misfiring issue at your home or office.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Q: Car is misfiring

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: increased engine over load message.

Hi there. The message is coming on for the catalytic converter overheating. A misfire or leaking injector will cause the catalytic converter to overheat as raw fuel enters the exhaust system. Check the engine for a misfire and see which...

Q: Would a click, click sound (battery 100% charged) mean a bad starter solenoid, or bad alternator?

Hello. We will be happy to assist you. The issue your vehicle is having may be caused by faulty wiring such as corroded battery to starter wiring or a loose battery terminal. The most likely causes are a bad starter...

Q: Ignition coil pack is not firing (1 out of 3)

It is not uncommon for an ignition coil to fail. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeated as the copper beneath them expands and contracts much quicker than...

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...