Blrfl
Natural Rider Enhancement
Probably not. If conditions are right for it, the fuel will explode early and there won't be a thing the ECM can do about it. Otherwise, the engine should run like it normally does.If falling back to open-loop mode, power and mileage drop should be noticeable, right?
There are multiple loops in the system; the one you're probably used to hearing about is the one with the oxygen sensors. Any other sensor that isn't critical to making the engine run also has a set of pre-programmed defaults that get used if there's a failure.
The knock sensors are different creatures. Because of they way they work, the ECM doesn't have an on-demand way to detect that they've failed and has to rely on inference. Above a certain speed, the engine makes enough noise that the sensors report that they're hearing something, which is one way to detect a failure. Depending on the design, pinging in one of the left cylinders might be audible by the right sensor, in which case the ECM could infer that one isn't working. Again, that's an educated guess. With no working sensors (and the ECM maybe not knowing it yet), the best it can do is time the ignition at whatever was determined to be ideal during R&D. If you ping, you ping, and like in the bad old days of fixed ignition timing, there's nothing you can do.
The magic number for that is 4,000+ RPM sustained for more then 10 seconds. At any rate, the two usual culprits are misrouted-and-cooked wiring, which was common before Honda figured out they had a problem. There have also been some failed sensors, and the easy way to check for that is to swap them and see if the code changes.Lately MIL hasn't blinked 25 on start up anymore. It goes off normally on restart and doesn't come back on until sustained highway speed.
Some 2003s report the wrong sensor, or maybe they report the correct one and the manual was wrong. We never did run that one down solidly.
--Mark