Knock between shifts

[LOL WUT]

Currently seeing 3-4* of positive knock on wot shifts (6speed, ESS G3, Verified E85). Single gear pulls are not seeing knock.

I’ve gone over the car with a fine tooth comb looking for any potential culprits and can’t seem to locate anything obvious with the exception of my headers being about a 1/4” away from my AC line (no obvious signs of contact being made).

Having said that, am I absurd to consider desensitizing my knock sensors with the understanding that I am only running verified E85 at 85% ethanol content?

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[junits15]

Currently seeing 3-4* of positive knock on wot shifts (6speed, ESS G3, Verified E85). Single gear pulls are not seeing knock.

I’ve gone over the car with a fine tooth comb looking for any potential culprits and can’t seem to locate anything obvious with the exception of my headers being about a 1/4” away from my AC line (no obvious signs of contact being made).

Having said that, am I absurd to consider desensitizing my knock sensors with the understanding that I am only running verified E85 at 85% ethanol content?

Don't do this

If you really want to do it, verify it yourself:
Take out a bunch of timing so that there's no chance that the motor will knock, then take more logs, if you still see the knock then you can be sure that its false knock, if you don't see it any more then its real knock.

I'm betting its false knock, when you lift off the engine will torque the other direction and its probably hitting something. Charge pipes can do this if they hit the frame or the radiator. The issue with desensitizing the knock sensors is that they wont work as well when the knock is real. I suppose you could make up for that by making the KR value more negative.

 

[LOL WUT]

Thanks for weighing in @junits15

 

[junits15]

Thanks for weighing in @junits15

good luck! hope you get it figured out easily!

 

[Zrussian13]

Hope you have better luck than I did with this issue. I hunted for it for over a year before desensitizing the knocks. Same symptoms though. About 3-4° on shifts but single gear pulls looked perfect. Boostane and pump has been good to me at <11bs of boost with knocks turned down. I've been contemplating how I'll go about it once I switch to E. Maybe limit timing by a degree or 2 or maybe set a limit boost? Just not sure yet but I'm pretty happy how strong it's running right now so I might just leave it be for a bit and enjoy it... minus my selfed caused issue that happened today but I'll save that for another day so I don't jack up your thread. Good luck!

 

[LOL WUT]

Hope you have better luck than I did with this issue. I hunted for it for over a year before desensitizing the knocks. Same symptoms though. About 3-4° on shifts but single gear pulls looked perfect. Boostane and pump has been good to me at <11bs of boost with knocks turned down. I've been contemplating how I'll go about it once I switch to E. Maybe limit timing by a degree or 2 or maybe set a limit boost? Just not sure yet but I'm pretty happy how strong it's running right now so I might just leave it be for a bit and enjoy it... minus my selfed caused issue that happened today but I'll save that for another day so I don't jack up your thread. Good luck!

Thanks for the well wishes! The good news is I am not really frustrated at all. I understood these types of issues would be a real possibility when boosting.

I do wish I had done more logs on 93 with gear changes prior to switching to E85 so I had an apples to apples comparison. Nearly all my 93 octane logs are single gear logs with up to -7* of KR.

Now that I switched to E85, WOT seems to show 0.00 KR until my gear change from 3rd to 4th where it will occasionally pick up 1-4* of positive KR.. When at 0 KR I am getting 20.5 degrees of total timing so I assume my targeted max timing at WOT is 20.5 which is why KR remains flat at 0 (essentially I am not getting any -KR at WOT because the car is achieving max timing).

I’ll poke around a bit more this weekend to see if I overlooked something (5 times lol) that may be causing this occasional positive KR at the top of 3rd into 4th.

 

[NGOT8R]

Are your IMRCs locked out? If so, did you secure your electrical connectors with zip ties, so they don’t rattle? They’re in close proximity to the knock sensors and could very well be the cause of false knock. I plugged up two of the connectors and zipped the other two to the clutch line and a wiring harness.

 

[LOL WUT]

Are your IMRCs locked out? If so, did you secure your electrical connectors with zip ties, so they don’t rattle? They’re in close proximity to the knock sensors and could very well be the cause of false knock. I plugged up two of the connectors and zipped the other two to the clutch line and a wiring harness.

Yessir I actually did this because I found you providing this guidance in a previous thread (thank you!). I’ve got the sensors capped and zip tied to the wire loom against the firewall. Appreciate the suggestion though!!

 

[NGOT8R]

Another culprit could be the counterweight on the right side of the transmission. You said the knock occurs during shifts and that weight rattles like crazy.

If you can, slide up under the car and wiggle the weight and you’ll be able to hear how bad it is. Rattle on the tranny which is transferred to the engine where the knock sensors sit.

 

[LOL WUT]

Thanks @NGOT8R ! I’ll hop under there tomorrow evening and check it out.

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