Knock knock, False knock? LS3 mutant in C5 car LS1 pcm

[BHC5]

Hello members of the board!
Newby novice here. I've recently completed a mutant LS1-2-3-7 motor build and stuffed it into my old turd C5. After learning how important injector data is, I finally have it on the road beginning my journey with tuning. I'm about 80% happy with the VE tables, but I'm seeing Knock Retard when I crack the throttle past 40% around 3000rpm+ downshifting before blasting. Also have some KR when at WOT. I've tamed down the timing tables (so I think) and tried to get HIGH / LOW / BASE Spark all in the ball park so nothing is jumping around.

The car is a C5 using LS1A pcm 24x crank, LS3 block, LS2 TB, recycled LS1 map, recycled LS1 valley type knock sensor on the side of the engine block. I only have one sensor connected right now (the second one was touching a header primary)

Here's my tune and a log. Any insight would be greatly appreciated thank you.

[joecar]

You log shows that it might not be real knock... but maybe something hit (exhaust on chassis...?)



BTW: smooth your VE table (it can't interpolate easily like you have it).

[BHC5]

Thanks for your reply Joecar. I will get to smoothing.

[BHC5]

maybe something hit (exhaust on chassis...?)

DING!!! Second opinions Rock... I'm running those silly DynoMax VT mufflers with the flappers inside them... I bet they're causing the KR I'm seeing. Thanks again Joecar.

[joecar]

Do you have a Chassis Ear (or some other listening phone)...?

[BHC5]

I do not. Where might I find something like that? If not too crazy $ I could purchase one.

[joecar]

ebay

The non-wireless ones are about $100. The wireless ones are about $200.

Depends on how intense you are with your car, the Chassis Ear comes in useful when trying to locate the source of any kind of noise (of course, I sometimes still fail).

[BHC5]

Did a little test. I wired the flappers in the mufflers to be open all the time. Went out for a test log, and Success!!! I had full timing until my riggings got hot and one side closed/got loose on me. LOL So now I know why Dynomax has discontinued those VT mufflers... The flappers may cause Knock Retard.

I found a ChassisEar for $108 on a tool website, (not sure if I'm supposed to suppress other sites?) Tool topia. Looks like something I could use. Thanks again Joecar for the help.

[joecar]

Good job

( you can mention other sites, if there's a problem I have the ability to sanitize )


I use the non-wireless ChassisEar for suspension squeaks/rattles, noisy wheel bearings, and other things.