Background - My 2007 Honda Fit started periodically shuddering/vibrating (I think this is what misfiring feels like). At first there seemed to be no real pattern to it...happened when accelerating and when idle, seemed worse when driving for longer periods of time.

There was no check engine light, but I took it to my Honda dealer anyway. They called me back later that day and said that the problem didn't occur when they drove the car. I insisted that they needed to drive the car longer and do some additional tests since I am paying for a diagnosis. They eventually called back and said that they felt the shudder/misfire, whatever and that they checked the spark plugs and found a couple bad ones so they replaced all of them. My car has about 75k miles, so it is not unreasonable, but I was a bit skeptical.

When I got my car back it seemed better, but after a few days it was obvious the problem was not fixed. After driving it for a while now it is apparent that the problem occurs almost exclusively when I am accelerating on an incline past 2,000 rpm. It also happens sometimes when I am driving at higher speeds and accelerating past 2,000 rpm and less frequently when idle.

Since the spark plugs were replaced, that isn't the cause. Any ideas? I really don't know much about cars. Thanks.

 

There have been numerous cars with the same symptoms that had bad coil packs.... Each spark plug has an individual coil that is attached directly over it and they are pretty costly at the dealerships... They can be purchased online from College Hills or Majestic Honda for much less... It is hard to diagnose which to replace but generally a person will buy one and replace the one they think is causing the problem and take a test drive to be sure then try again exchanging the new coil with a different used one until they get it right.. Some have replaced all of them at once just to get it over with and not have to worry. It's about $250 for all of them plus shipping from Majestic. The are easy to install for anyone that is handy with automotive tools.

 

Thanks for the information. Can you test the ignition coils first before purchasing new ones?

 

No, that is why it is a good idea to buy one and use it one at a time on each spark plug.... There is thin, wires that make up the coil and a slight break will only show up by causing the engine to stutter under certain conditions relative to temperature and vibration.... If the coil winding was completely separated at the break it would be easy to find with an ohm meter..... I only have 33000 miles on my 2007 model so I know the day is coming when I will have to deal with the same problem... I am thinking about ordering the coils in advance just in case I am in need of them when I am away from my house.... I have wondered if there is something that the owners that have had this happen have in common like the type of fuel they use, transmission type and urban or rural driving.