Hello all,
Yesterday morning my '92 Nissan Sentra (GA16DE engine) ran great. Two hours later when I started it up, I experienced rough idle, bogging on acceleration and a significant loss of power on acceleration.
I changed the spark plugs today, hoping that would fix the problem. (The old spark plugs appeared to be worn, but otherwise normal. No evidence of improper combustion.) When I started it, the same symptoms occurred. I drove it around town to run errands anyway. About 10 city miles later, I parked, let it cool for an hour, then pulled the plugs to see if there were any anomalies.
I found the 1, 2, and 4 spark plugs had a very light greyish-tan coating, which I believe is indicative of normal combustion. The #3 plug appeared to be completely clean, as if it had come right out of the box.
Is this indicative of a fuel injection problem? If so, how can I test the fuel injector? Any thoughts on likely other causes?