We have spent the weekend playing diagnostician and are completely stumped.
The the car has always had a minor problem of occasionally stumbling when you first pull away from a stop and would occasionally cutoff when pulling quickly to a stop or slowing for say a u-turn. Due to its lack of frequency, this we have given up on and I have learned to live with it.
However, lately it has developed a phenomena that I cannot live with. The car runs fine under moderate load and below 2000 rpms. Under moderate to heavy acceration or anything above 2000 rpms, it stumbles terribly. Engine analyzer reveals that #2 cylinder is dropping our intermittently as it approaches 2000 rpms and drops out COMPLETELY at 2000 rpms. Above 2000 it is dropping out intermittently.
We found a cracked distributor cap with a hairline fracture which seem to start at the #4 terminal and radiate to the #2 terminal. Replacing the cap did not change anything.
We replaced the #2 plug wire, the #2 plug, and still no change.
I understand that there is a pickup sensor inside the distributor. Could the pickup sensor or something else in the distributor be faulty or worn out, or would it affect all cylinders?
While it does not feel loose, is it possible that there is
some wobble in the distributor that is causing the rotor to hit the cap at #2 and #4 (nearly opposite sides)resulting in
both intermittent ignition and cracking of the cap?
Could the ignition amplifier(CD box?) be bad, or would it affect all cylinders?
The local shop is stumped!
Any ideas are welcome, we will resume our efforts on monday.