[DJR]

I have a 1999 Honda accord Ex. 247,000 miles. I finally got around to changing the motor mounts the other day, and when I got it all done, the motor shakes pretty noticeably. I can feel it inside the car, and it wasn't there before I changed the mounts. (the old mounts were cracked). I was checking the computer with my OTC scan tool, and noticed the timing advance was jumping from 7 degrees, to 20 degrees, and for a split second, it jumped to something like 50 degrees, but then would immediately go back to 10-18 degrees. It feels like the motor is misfiring, but the scan tool didn't detect any, and there are no codes. I cleaned the intake, the IAC valve, and it has fairly new plugs/wires, cap, rotor, etc. As soon as the engine is revved up to about 1400, the vibration is gone, and the timing advance stays at 8 degrees, until I let off, and it goes back to idle where it jumps around. I'm at a loss. Any advice?

 

[nehonda]

Check for loose/damaged wiring or connectors on sensors near the motor mounts would be my only suggestion. ECM may be getting strange signals causing it to vary the timing, knock sensor possibly? Maybe it will throw a helpful code if you drive it some more.