Knock sensor questions

[Coygiles91]

2007 Super Air 220 with 500 hours.. knock sensor comes on randomly and then will go away once I slow it down, I can speed back up and it does not usually light up again. I know bad gas could cause that but Ive got some new fuel in it now and had to of ran out all the residual fuel. My prop needs to be replaced because it has a bad vibration at moderate RPM and it made me wonder if the sensor can pick up that shudder and make it go off?

Either way I've got a new prop and knock sensor on the way. I don't have the manual so I'd like to know where exactly the knock sensor is on the block?

Any insight helps. thanks!

[Nautiquehunter]

A knock sensor picks up vibrations from pre ignition or spark knock. It will also react to any vibration on the engine . Check and make sure everything is tight, brackets, pulleys and the sensors themselves.

[Quinner]

On a Vee drive for sure on the Port (left) side however some Excaliburs have 2 sensors, one on each side. They are installed in the drain plug hole. Do not use any Teflon, raw threads only and snug is all you need, spec is something like 20ft/lbs iirc. The electrical connection is removed by squeezing 2 sides which opens it up to remove.

[skiinxs]

Prop vibration can certainly cause knock sensors to pick up the harmonic vibrations and falsly indicate there is detonation. If I were you I would put a good prop on before you invest any more time on the knock sensors.

[Coygiles91]

New prop fixed it!!

[skiinxs]

That is great news, I thought that was the issue. If I were you I would disconnect the negative battery cable for a couple minutes to force the ECM to relearn. You are probably running in detuned mode from the knock sensors picking up the prop vibration. The ECM thinks you are running very low octane gas and may take a tank or two to restore full timing advance. You can eliminate that process by forcing it to relearn.