09-29-2014, 12:06 PM
Interesting. If the engine was cycling rich/ lean, how long would these cycles last, hours, minutes? The manifold is cracked, which I think could have set it off. (I was considering replacing the O2 sensor at the same time as the manifold hence the original question).
I did notice the engine has several distinct "modes" of idling. Sometimes it is at about 800 rpm and the rpm plunges maybe down to 700 or 600 (hard to tell on the tach it's pretty fast) and immediately goes back to 800, this happens regularly a bit more than once a second, it sounds like the engine is revving. The other idle "mode" is way high like 2k rpm but steady. Is this from cycling rich/lean?
I did notice the engine has several distinct "modes" of idling. Sometimes it is at about 800 rpm and the rpm plunges maybe down to 700 or 600 (hard to tell on the tach it's pretty fast) and immediately goes back to 800, this happens regularly a bit more than once a second, it sounds like the engine is revving. The other idle "mode" is way high like 2k rpm but steady. Is this from cycling rich/lean?
1993 4 door JX 16v fed manual all stock