Bob B

Here's a question:
I am wondering about all the engines that have the knock,
Wouldn't the knock sensor hear it and retard the timing, thereby costing you power and fuel?

Part 2: Is the knock only with the newer engines after 98?
Would a 97 5.7 be likely to have it also?
Bob B

2000CAYukon

The job of the knock sensor is to protect the engine if dentonation is happening. If you get false knock it can rob you of power but should also set a check engine light if it does it too often.

A knock sensor can be found on most efi cars and trucks. My 90 K1500 has one.

//2000CAYukon

Bob B

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Yes I know that. It's why I asked the question.
Let me add to the questiion.
I'm asking if your truck has the in famous piston slap knock, would the sensor feel it and retard the timing as if it were preignition noise?
Bob B

2000CAYukon

Piston slap usually only lasts for a short time at startup. Your best bet is to use a scan tool and watch how much timing is being removed due to knock being picked up by the sensor.

Yes, if there is noise coming from your engine (a bearing knock for example), then the timing will be retarded.

//2000CAYukon