CB1100 Idle speed instability problem

[dave]

Here’s the latest concerning my low RPM/stalling turned high RPM (1,500 RPM), turned low RPM/stalling again situation. Maybe my post will give somebody an idea that may somehow lead to a solution? My bike had been running nearly perfectly for the past (approx.) 2,000 miles, and now the last three times I have ridden it after it reaches operating temperature it will go into the low RPM/stall mode when I attempt to allow it to idle in neutral at a stop light. I can keep it running by blipping the throttle, and if I blip the throttle enough times it will eventually “slowly” work its way from about 500-600 RPM up to the normal 1050 – 1100 RPM. I can definitely say the low RPM/stalling is not caused by excessive heat, or slow moving/stop-and-go driving. I reached home tonight when the bike was experiencing the low RPM/stalling condition and it stalled as I drove into my driveway. I turned off the key, and after getting a flashlight I unplugged the Engine Oil Temperature (EOT) sensor and restarted the bike. Mysteriously, it began idling fine, at approximately 1,050 RPM. I went on a short ride in the neighborhood and did multiple stop and goes, and the low RPM/stalling did not return. I returned home and turned the bike off with the key, and plugged the EOT sensor back in. I restarted the bike and it was idling fine. I went for a short stop-and-go ride around the neighborhood again and the low RPM/stalling condition came right back. I pulled into my driveway and kept the bike running by blipping the throttle until it eventually “slowly” worked its way back up to a normal, 1050 RPM idle. As I allowed the bike to sit and idle I disconnected the EOT sensor, and the engine immediately stalled. I restarted the bike (the key was never switched off), and with the EOT sensor disconnected the low RPM/stalling condition was back. I turned the bike off using the key and let it sit for about a minute, and restarted it. This time, with the EOT sensor disconnected, it returned to a normal idle. I turned the bike off with the key, plugged the EOT sensor back in and restarted it, and it was idling fine again. In frustration I put the bike in the garage and walked away. So my observation is this: If I am experiencing a low RPM/stalling condition and turn the bike off using the key and unplug the EOT sensor, the condition will go away when I restart it. If, when I am experiencing the low RPM/stalling condition and I disconnect the EOT sensor without turning the bike off using the key, the low RPM/stalling condition will not go away (it may actually get worse). For some reason the bike needs to be shut down prior to disconnecting the EOT sensor for this procedure to have any positive effect. Does this information possibly provide a hint to a solution to any of you guys out there who have a much better knowledge of how these computer-controlled fuel injection systems work?