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Knock Sensor options

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Please pardon my ignorance, I'm trying to learn. I want to know if I can upgrade from a 1 wire resonant knock sensor to a 2 wire flat response KS for my current application, and if doing so is actually a smart move.

My engine is a 468 BBC with a custom HR cam, roller rockers, headers, and controlled by a Holley Dominator ECU. It currently has two 1 wire sensors in the block near the pan rail, i.e. in the drain plugs like an L29. It's a fairly tame build, and probably isn't knock limited at 8.7:1. However, I'd really like to know that it's NOT knock limited!

So, I bought a Plex V2 about three years ago, and have used it only once with mixed results. Not sure I configured it correctly. It came with a pair of Bosch two wire sensors. I thought it would be a good idea to use those to try and dial-in the 1 wire KS's, i.e. replace one of them with a two wire Bosch sensor, then use the Plex to identify the knock, and then adjust the frequency and sensitivity in the Holley ECU for the one wire KS. But would I be better of just replacing the one wire KS's with the two wire KS, i.e. are two wire KS's a better solution?

Glen those are great thoughts and questions.

Honestly Holley can likely best answer which sensor best matches their onboard strategy, but since you have the Plex system, I'd install their 2 wire sensor in addition to what Holley suggests, to allow you to monitor for knock yourself. You can stack them using a longer bolt.

If you're able to adjust Holley settings to correlate with what you're hearing using the Plex system, great.

If not, at least you can tune using the Plex system manually.

Thanks for the reply. I did contact Holley about an hour ago. However, the guy that answered could only say that the ECU will support whichever I chose (1 or 2 wire) as long as I adjust the settings appropriately. Well, that and that someone told him that knock sensors are for lazy tuners that don’t know how to properly tune the spark table. I find that tech support is hit or miss depending on who picks up your call.

I plan to use the Bosch sensors that came with the Plex. I’m hopeful that they’ll work perfectly with the Holley, and if so I’ll use them on another build that is getting a Nexus R3.

Great, using the Bosch sensors seems the right move.

I understand many folks using Holley don't tune fuel or spark and simply let the trims sort of make the engine run, but it's far from ideal and I'm glad you're looking to do the job right!

I suspect that's what they were hinting at when they referred to lazy tuners, but that's more along the lines of NOT tuning ignition timing and letting it ride the knock sensor, vs. actually tuning the engine properly, then leaving knock control present in case conditions are unfavorable at some point in the future, perhaps from poor fuel or otherwise.

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