need help finding false knock?

[lxgt302]

I need help finding knock,did dataloging with hope of getting aed tune. and shaun reported that I had a knock. so to start finding it I ran all fuel out and refuel with Sunoco 100 octane. same results knock sensor pull timing out.
its a 2014 gt m6 all stock etc.jlt cai, jms 91 octane tune, gt500 mufflers,dei intake insulator, 3.31 gears. so I have a false knock. check exhaust system an nothing loose or touching. it has 7000 miles. thanks guys in advance.

 

[Voltwings]

Anything loose or rattling in the engine, loose exhaust bolts, if the intake is tapping the fram rail... i have dealt with some very sensitive knock sensors before, you just need to make sure everything is bolted in place tight and not tapping / rattling against the motor at all.

Whats a DEI intake insulator?

 

[GT915]

If it were me, I'd do a KAM reset and then log it again. If it is still pulling timing, I'd reinstall the stock airbox and reflash it with the stock tune and try again. While I have no experience with the sunoco 100 octane, I do know that I have bought premium fuel, that was NOT premium and have the data logs to prove it. I found all of that out when I was getting my tune. Good luck and keep us posted.

 

[Shaun@AED]

It may be a good idea to do a sticky on where people have found their *false* knock to be coming from.
The most common places from my experience are in the pic below, circled in Red:
1. Cat to H-pipe clamp installed upside down so bolt head is down and threads re UP hitting the under carriage.
2. X/H pipe cross over too close to the trans cross member.
3. Over the axle pipes hitting suspension components or Rear end (common on lowered vehicles)
4. Loose axle back clamps

Keep in mind, the engine will torque over to the passenger side during heavy Acceleration, which means when on jack stands everything may clear just fine, but under WOT / heavy acceleration the exhaust may hit something. The same goes for the suspension. On heavy launches the car may squat and the exhaust may hit suspension components or the rear end.

 

[92fiveohfox]

Very informative thread. Thanks for the info Shaun.

 

[06Bluerex]

good info

 

[lxgt302]

thanks for all the great info, the car is at the stock ride height,will check under carriage again,and try kram the memory ,themal heat shield on bottom of intake,will keep you guys posted thanks again SVT friends .

 

[hoodley]

so if the ota pipe hits rearend or body, does that damage pipe or loosen fasteners???

and if so would a leak that far back cause a knock condition? just asking b/c what if the pipe was cut off before there. how would that affect it?

 

[Jsmorley81]

I've got false knock too, and can not figure out where it's coming from. I'm in a 2013 with 15k.

 

[cb900f]

so if the ota pipe hits rearend or body, does that damage pipe or loosen fasteners???

and if so would a leak that far back cause a knock condition? just asking b/c what if the pipe was cut off before there. how would that affect it?

It's not a leak that is detected as knock but it tapping on the body/rearend/wherever. That sound is resonated up the pipe to the knock sensors.

Example:

On a hard shift the mid pipe flange hits the frame, that "bang" is resonated up to the motor and is picked up as knock. Knock sensor goes off and retards timing by say 4 degrees. No more knock is detected so timing is slowly added back in. (Stair step look on the datalog)

Shift again, bang, retard timing, slowly add back in.

Etc....

 

[5.0jake]

False knock sucks and is no joke. When the knock is detected, timing is pulled and performance is lost!
Another thing that sucks, is that it's possible you're facing false knock AND crap gas induced engine knock at the same time. That can't be 100% ruled out until the false knock as been addressed.
I too have been chasing false knock. Ive also run my tank dry and ran pure Sunoco 100 octane to be sure. What's weird is when I tune back to stock there is little to no knock but with the tune (probably due to the extra torque) I see knock activity, especially at tip in.
In my case, my axleback was loose, and once tightened, the knock improved but NOT completely resolved. Another thing I noticed was revving in neutral has induced false knock (not under load) any thoughts there?

 

[KILRSVT]

Would valvetrain noise induce false knock? Also I would reinstall the stock air box since the open type intake will heat soak during a stop or idle.

 

[466roller]

I've seen defective tensioners/idler pulleys cause a false knock reading on cars at work. I don't work on Fords and it's only been twice, still a possibility.

 

[5.0jake]

Ive also heard that the knock sensors themselves could be the issue (possibly defective, too sensitive...).

 

[nikleondis]

I'm currently going thru the same issue with lund tune. Added 2 bottled of lucas octane and tried 6 different Gas pumps for bp 93 and she'll 93. I'm doing seafoam tomm and replace jlt separater with breathers. My long tubes are 1/4 inch away from some stuff on passenger side so I'm buying steeda adj. Motor mounts to raise my motor half a inch and hopefully give me more clearance. If that doesn't work then I'm looking at e 85. This knock is a ****ing nightmare. Do u have any updates?

 

[GrabberOrange]

Hi, I know its an old thread but any updates?

I'm having the same issue for almost a year now and cant seem to find a solution.

 

[daustin]

Shaun@AED posted a video on his YouTube page to help track down false knock. Search for "classic case of 'false knock' on a coyote." I never had to deal with this, but hopefully the video can shine some light on it for those that do.

 

[3unn]

False knock can also hurt fuel consumption if it happens at part throttle an cruise.

 

[railroad]

I did a dyno data log to fine tune my 13 Shelby, 13-6 kit, 93 tune, TR-6s, upper pulley and JLT. I had a max of 2* of KR. It kills the power. I was running 93 Chevron, but hope to change over to Sunoco, change the plugs to TR7IX and maybe change from Castrol to Amsoil 10w-40. All stock exhaust, so should not be having any banging going on. Will eventually get it on the lift and double check.
I have a piece of foam tape on the bottom of the JLT CAI tube over the valve cover. I may stick a piece on the bottom of the catch can. I had some random P0300 codes, about 5 times after the bolt on mods. Snoopy, came up with the resetting the KAM and CRANK RELEARN, which has stopped the pop up codes. I suspect the two issues are related. 3200 total miles on the car. Car runs good, nothing you can feel by the seat of the pants. Cannot imagine how good the car would be with full ign timing.
I do have the BMR susp, and do get a clunk with extreme changes in drive line load. I do not think this would show up on a dyno with one gear pull from 2K to 7K rpm. Obviously there are similar issues going on out there. I hope this thread does not go off topic like some. I would like to compare notes with anyone dealing with the same.

 

[lxgt302]

****** up date*********

well its been a year and here are latest finds, living in the inland empire we have bad fuel.
to get a data log with no knock activity I used 100 octane race fuel, preform three wot 2k to 7k runs then data log. aed recommend mild pump gas tune or e85 . current comb is roush stage 2 85mm pully. btw it runs really good.