Still Can’t Solve Knock Issue

[TheHydro]

Maybe try pulling your belt and checking all of your pulleys, try turning the supercharger by hand while at it. Seems like you have tried everything. Turn waterpump as well. Just a thought

I have had the belt off several times and checked the pulleys to see if any had play in them that might cause some noise or vibration but didn’t notice any and the blower turns smoothly by hand. I haven’t check the water pump so that is an idea. I really do appreciate everyone’s input because I’m lost at this point. I’m tired of opening the hood and staring at everything trying to find something I haven’t done yet.

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[5ohh_kenny]

I know it’s a ton of work but have you tried removing the blower. Going back to stock then monitoring for knock? If your out of ideas that may be your Hail Mary. If that works, sell the blower and go turbo

 

[5ohh_kenny]

That or shut off your knock sensors. Your running E85 so you aren’t going to be getting legitimate knock.

 

[sabtaj1]

Has this been ever since you installed it? I would say maybe something in the valley under the blower but if only lower rpm?? dunno.... any unused plugs flopping behind the whipple? im sure you are going nuts.

 

[TheHydro]

I know it’s a ton of work but have you tried removing the blower. Going back to stock then monitoring for knock? If your out of ideas that may be your Hail Mary. If that works, sell the blower and go turbo

That’s funny you mentioned it because I actually considered it. I always like the idea of more power but even with my setup right now do a 70 roll the rear end gets squirrelly with a fresh set of drag radials. Turbos turned up have to really have a pucker factor. If I ever got a chance to drive a turbo coyote and liked it I would make the switch.

 

[TheHydro]

Has this been ever since you installed it? I would say maybe something in the valley under the blower but if only lower rpm?? dunno.... any unused plugs flopping behind the whipple? im sure you are going nuts.

I ran the setup without issue for several thousand miles. I did the rear end stuff, DSS driveshaft, and a few more rear suspension pieces and started noticing the issue. I got rid of the DSS and went with a Dynotech driveshaft which is much smoother and that made no difference. I’m going to try some of the suggestions on here as well put the stock driveshaft back on and see if maybe that soaks up vibrations from the rear end or something. I also considered the plugs from the stock intake manifold but since day one they were taped up and zip ties to the world harness and didn’t have an issue for several thousand miles.

 

[sigintel]

I ran the setup without issue for several thousand miles. I did the rear end stuff, DSS driveshaft, and a few more rear suspension pieces and started noticing the issue. I got rid of the DSS and went with a Dynotech driveshaft which is much smoother and that made no difference. I’m going to try some of the suggestions on here as well put the stock driveshaft back on and see if maybe that soaks up vibrations from the rear end or something. I also considered the plugs from the stock intake manifold but since day one they were taped up and zip ties to the world harness and didn’t have an issue for several thousand miles.

"plugs from the stock intake manifold" pictures?
From an engine survival standpoint, I have seen a small leak before where unmetered air can get in just enough to cause lean det at low rpms, but once you get higher, the small amount of air is no longer enough to cause lean det.
This was NOT on a coyote motor/ECU; I am guessing y might see the coyote ECU compensating in the logs for a small air leak.

Switching back to stock driveshaft just to test sounds like excellent idea as well.

 

[AZ_whippleS550]

you have solid diff bushings right? I would try to go with a rubber bushing and see if that makes a difference Since it started after you did the rear end stuff.

 

[Burkey]

To me, what you’re saying is fairly consistent with an engine that’s actually twisting and making contact. You say it doesn’t do it in the first 2 gears, I assume because you have no traction.
As someone else highlighted, it’s happening at somewhere near peak torque (twist) and in a gear or gears where you’re actually able to create some grip.
Any chance the headers are hitting on the steering column (or something equally silly) when the engine torque-twists?
Out of interest, what sort of timing is the car trying to make when this happens?

 

[TheHydro]

To me, what you’re saying is fairly consistent with an engine that’s actually twisting and making contact. You say it doesn’t do it in the first 2 gears, I assume because you have no traction.
As someone else highlighted, it’s happening at somewhere near peak torque (twist) and in a gear or gears where you’re actually able to create some grip.
Any chance the headers are hitting on the steering column (or something equally silly) when the engine torque-twists?
Out of interest, what sort of timing is the car trying to make when this happens?

That makes complete sense. I’m sure something is hitting I just can’t find where. I checked the header clearance and they don’t seem close to anything. My MGW shifter is very close to my driveshaft though.

 

[Kong76]

Are you shifting by any chance when the knock comes in? Can the data log determine that?

Nevermind you said it comes in during third pull.

 

[GuardGT]

I have fought false knock multiple times, but I have a Paxton car. Mine always came in when the engine torqued, and to my surprise the engine moved A LOT more than I expected. First mystery was the stubby filter hitting the radiator shroud (had over 1/4” clearance), second was a charge pipe hitting the back of the marker lights in the front bumper. 3rd time I installed resonators and they hit the floor pan. Fourth time I blew something in my muffler and it was vibrating. Fifth was an AC line hitting a charge pipe. 6th was a small exhaust leak. 7th was the hood prop. Moral of the story... literally ANYTHING can cause false knock from hell.

So, I bought adhesive back weather strip and foam strips (on amazon), a roll of gorilla tape, a big ass hammer, and exhaust wrap, and went front to back of the car padding and clearancing any hard surfaces that might contact under torque. Now I have negative knock everywhere and the car hauls ass. I wish I had a direct solution, but I hope this helps give you ideas of what could be knocking and what to look for.

 

[Luce202]

You’ve probably already done this but I figured it wouldn’t hurt to throw it out there. Have you removed the line bracket on the passenger side that is close to the exhaust manifolds? The tip of the bracket stud/bolt is notorious for contacting top manifold tube under heavy engine load/twist.

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