Hunting rpm

[dave]

Hi Dave. Not sure about the IACV motor cycling before it was replaced. The dealership replaced it a couple weeks ago after determining that it was faulty, and without any other changes, the high idle symptom disappeared.

Previously, the dealership had simply reset the ECU (no remap), and the high idle went away for a couple months. I noticed that several stop-and-starts in a row (like running multiple errands) would make the high idle symptom return. The dealership stated this was due to the IACV motor sending faulty signals to the ECU, thus putting the bike in a high idle "limp" mode.

YMMV, but I recommend asking to test the IACV motor without any sort of ECU work, and seeing if the high idle disappears. I have yet to do a stop-and-start trip, but will do so soon to see if I can trip the high idle and prove to the dealer that there is something else still wrong with the bike. I have six months of Honda Protection Plan warranty left, so I'd rather have the issue taken care of now.

Thanks for the feedback John. My bike is out of warranty and I want to avoid paying big $ to the dealer if I can, so I am trying my best to fix this problem myself (although I am beginning to think this is highly unlikely). The fact that unplugging my EOT sensor makes the bike run perfectly really makes me think that the problem has something to do with the computer recognizing the correct operating temperature of the engine and adjusting the idle speed appropriately. My original, and the first replacement EOT sensor, both measured out of specification according to the Honda shop manual, and I am now waiting for another EOT sensor from the dealer (they took the defective sensor back after they confirmed for themselves that it was faulty). Both my original and the first replacement sensors measured lower-than-designed resistance (1.9 K-ohm and 2.0 K-ohm, spec is 2.4K-ohm to 2.9 K-ohm). I wish I understood how the IACV, the EOT sensor, and the computer all work together because I think they're all related to this high / low idle speed issue.