Occasional knock after shift. Not WOT.

[ManBearPig]

I'm trying to diagnose the source of some knock I'm seeing under a certain set of conditions. I will occasionally see the car register 2-3* positive knock when rolling into the throttle after a shift. Not super heavy throttle, but not real easy acceleration either. The positive knock will stay for 3-4 seconds. Sometimes decreasing from 3*, down to 2*, down to 1* before the car starts adding timing. Sometimes it will stay at the same positive knock value until I let off. I can't capture this on a datalog because it's so unpredictable. I do much more frequently see blips of positive knock under similar conditions but im not as concerned with these as it's usually less than 1* and goes away almost instantaneously. I have seen this on my Lund tune and my stock tune, both with and without octane booster. I do not believe it to be related to fuel quality. I also don't believe it to be false as I have swapped the stock exhaust back on and cannot find anywhere that looks suspect under the car. I'm wondering if there are other things that can cause knock, besides octane. I've noticed in the datalogs I've taken that there is often a brief rich spike between shifts. This is both tuned and on the stock tune. Is a random knock event like this somewhat normal or can there be other things I should be looking out for?

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[BmacIL]

I would guess that's false knock if you see it on the stock tune. Maybe it's hitting something.

 

[v8hgt]

Manual car. Knock immediately after a shift. Got some backlash in your drive line and sensitive knock sensors have you. Or maybe a vibrating oil catch can...
The knock sensors are in my opinion overly sensitive on thes cars. Probably in order to cope with the massive variation in octane in the world market. Ask your tuner to turn the gain down a fraction and see if it goes away. Then stick a tank of lower octane fuel in and make sure real knock gets registered and timing pulled back appropriately.

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