The car started shaking when the gas pedal is not pushed hard and then it stopped in the middle of the road. Seemed like all cylinders suddenly stopped misfiring. We took it to ta Nissan dealership. They replaced the ignition coils and spark plugs and probably programmed the ECM too. I paid $1000 for it. The car ran fine for 2 days and again started shaking. There is no noise, just vibration which clearly is cylinder not firing problem. After it was shaking for a while, I stopped the car and restarted it again. It started shaking again as soon as I put it in Reverse. After a while the Service Engine Soon light came up. Not sure what exactly is the problem.

Hey guys.I have a Altima 2005 2.5L V4 (104k miles). Recently my engine started vibrating out of nowhere. It was just a slight vibration in the beginning but then it got louder and louder throughout time. I replaced my Crankshaft Sensor before that because I had "hard start" problems and then a month after that the Check Engine light came on with P0420 code. Some say it might be a Vacuum Leak or Fuel system failure.

At one time the Light turned off and turned back on after a week or two. I already replaced my Spark Plugs and cables, which made the car run a little smoother. Except the vibration is still there.

My Oil is not leaking, it's full all the time. My Engine Coolant has been on the same level ever since I bought the car. The only thing that messes with me is that the Fuel consumption has gone higher and it seems like my RPM goes a little higher than usual when hitting the gas pedal.

( I thought maybe I smelled something bad coming out of the exhaust but I am not sure)