My engine all of a sudden seems to have developed knocking on low RPM yesterday. This is a 1999 Nissan Maxima at 110,000 miles and I did all the required maintenance. While I was bring it to a local mechanic, the "service engine soon" light came on. The mechanics read the code and it is something like "knock sensor malfunction", and "#2 misfire", or something like that.
The mechanics is all booked this week so I will bring my car in on Monday for further diagnostics. In the mean time, someone suggested replacing my spark plugs to see if it helps, I know it was replaced at
60k, and maybe at 90k, not sure. So I replaced it this morning myself, double platinum plugs and gapped at 1.1mm, according to the repair manual. The 3 plugs in the front of the engine (easier to access to) seems aged less than the 3 plugs in the back. So perhaps the 3 in the back was not replaced previously?Unfortunately the problem remains. At low RPM, such as when I am driving on street, I can feel the steering wheel shake slightly. If I put it on neutral, it doesn't shake as much, but I can still feel the engine not running evenly/smoothly. At high RPM however, such as highway driving, the problem almost disappears.
I am not a car person and replacing the spark plug is about as brave as I am willing to go. I was hoping that it is the cause but it's not. What other factors could be causing the engine knock? Anything I can do to check myself? My car does not have a distributor cap, and the cable for the spark plug does not look like it can be replaced either.
I've did all the required maintenance, 60k, 90k, etc. but not an engine tune-up. Could this be because I didn't do any engine tune-up?
Thanks!
Raymond