False knock or real knock with engine rev?

[ManBearPig]

I just put a set of cat deletes on my car. Factory shorty headers, just deleted cars and flex pipe. I've noticed now that under the right conditions, if I give the car a hard rev, I'll see some +knock on the knockr pid. I've never noticed this before, but I've problem never revver the car like this either. Can I write this off as unavoidable false knock from the knock sensors getting triggered as the engine torques? Or could it be true knock at throttle tip in? Or even Just excess vibes in the exhaust now that it is more rigidly mounted (no flex pipe). curious if this sort of thing is to be expected?

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[Bartly]

I just put a set of cat deletes on my car. Factory shorty headers, just deleted cars and flex pipe. I've noticed now that under the right conditions, if I give the car a hard rev, I'll see some +knock on the knockr pid. I've never noticed this before, but I've problem never revver the car like this either. Can I write this off as unavoidable false knock from the knock sensors getting triggered as the engine torques? Or could it be true knock at throttle tip in? Or even Just excess vibes in the exhaust now that it is more rigidly mounted (no flex pipe). curious if this sort of thing is to be expected?

I diagnosed my knock to be real with gas additive like Torco, when it's mixed in the tank the registered KR goes away, without it it's in the positive. With you just doing exhaust work, yours could very well be something rubbing or loose, I only say that because there sure are lots of reference on the net to exhaust work causing knock.

 

[ManBearPig]

I think false knock from exhaust hitting the body is more evident. I never see any positive values under part or full throttle. Not even with an aggressive shift. Which is what leads me to believe the knock may be real....but realistically I'm not sure it's an issue. It's asking a lot of the computer to prevent knock with sharp throttle stabs from 3-6k rpm without load. That's prime knocking opportunity and I'm just curious if anyone else experiences this?

 

[Ecoboosted]

Post #15 has a video with the guy explaining a couple of places that can touch the headers and create a false knock http://www.mustang6g.com/forums/showthread.php?t=89087

 

[ManBearPig]

I don't have longtubes...just the factory sjorties with cat deletes. There is plenty of clearance up there. I also don't see any knock under any driving conditions...just a hard, quick stab of the throttle with no load (hard rev) I guess I included too much info because my only real question is...Is a quick positive knock under this condition acceptable?

 

[Rhodes]

Hi Brian, I too have this. My tuner has confirmed it to be real and has decreased it by decreasing timing and increasing fuel in those conditions but i still have it. (roughly 2-4k, 50% throttle/tip in). Mine seems air temp related also somewhat. Have you had any luck finding a fix?
FYI i have longtubes, CAI and tune.

 

[ManBearPig]

I went as far as putting the factory headers and catback on, went to the factory tune, and tried some VIP octanium. I really don't know if it's real or not but I can't fix it so I gave up. I usually have to give the car a few hard revs before it'll register any knock. Every now and then it'll show knock for a split second with a small blip though.

 

[Jayme]

it'll show knock for a split second with a small blip though.

mine does the same thing SOMETIMES under a hard rev but not under load.

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