How much KR is too much?
Thread Starter
Drifting
Joined: Dec 2016
Posts: 1,377
Likes: 219
How much KR is too much?
Just finished datalogging a diablosport intune with a WOT run, from 0-100ish, there are absolutely no knocks except for shift knock (not real knock, from what I have read), and from about 100-120, i am getting ~ 6 degrees of KR. Is this normal?
Just learning how these things work and i am in over my head... I just read all 30 pages of:
https://forum.diablosport.com//viewt...=917&start=315
and while informative, it gives no good "rule of thumb" that tuners with experience have...
Also, I am getting ~-7% LTFT bank 2 and ~+4 to -4% LTFT on bank 1. i am fairly certain I have a small exhaust leak (exhaust tick noise) post manifold on bank 1 - that means i am probably getting ~-7% LTFT on both banks? Should I be leaning out the mixture?
What else should I look for? Also, I turned down my rev limiter for reliability/longevity by 200rpm or so but im still redlining at 6400... is the stock LS3 engine a 6600 redline?
Just learning how these things work and i am in over my head... I just read all 30 pages of:
https://forum.diablosport.com//viewt...=917&start=315
and while informative, it gives no good "rule of thumb" that tuners with experience have...
Also, I am getting ~-7% LTFT bank 2 and ~+4 to -4% LTFT on bank 1. i am fairly certain I have a small exhaust leak (exhaust tick noise) post manifold on bank 1 - that means i am probably getting ~-7% LTFT on both banks? Should I be leaning out the mixture?
What else should I look for? Also, I turned down my rev limiter for reliability/longevity by 200rpm or so but im still redlining at 6400... is the stock LS3 engine a 6600 redline?
Last edited by Ahrmike; Sep 11, 2017 at 08:33 AM.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
In my experience with moderate cams, LTrims should not consistently be outside +/- 5%. -7% across a wide operating range indicates a problem. Likewise, an exhaust leak would not result result in swings form -4% to the 4%.
What mods are on the car?
What mods are on the car?
Thread Starter
Drifting
Joined: Dec 2016
Posts: 1,377
Likes: 219
Mods: No breathing mods, no exhaust mods (NPP open), no cam. I do have a catch can.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,403
From: Bethesda MD
It should only take one good drive for the tune to settle in. Once the car is warm, the LTRIMs start learning. Weather can have a small effect, so it doesn't hurt to take a second look since it has been a few days.
I've seen header leaks near or before the O2 sensors cause it to read lean. A leak well afterwards is less likely to have a big impact.
I've seen header leaks near or before the O2 sensors cause it to read lean. A leak well afterwards is less likely to have a big impact.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
You'll have fits trying to tune a car with an exhaust leak, that's likely the cause of your LTFT's. Get the exhaust leak fixed before trying to tune it.
Any knock is bad knock in my book, I don't like to rely on the knock sensors. if I'm getting any KR (particularly around torque peak, 4800 or so) I reduce timing.
If you reduce timing and it still knocks at the same rpm there it might be exhaust hitting something. Look at the floor pinch weld on the right side, it's often close to the headers, I had to massage my pinch weld with some big channel locks for clearance. I could hear it hitting when I lit into it and the engine moved over to the right a little.
Any knock is bad knock in my book, I don't like to rely on the knock sensors. if I'm getting any KR (particularly around torque peak, 4800 or so) I reduce timing.
If you reduce timing and it still knocks at the same rpm there it might be exhaust hitting something. Look at the floor pinch weld on the right side, it's often close to the headers, I had to massage my pinch weld with some big channel locks for clearance. I could hear it hitting when I lit into it and the engine moved over to the right a little.
Last edited by Joe_G; Sep 14, 2017 at 10:14 AM.
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Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
If your headers have a welded on strap that ties to the torque tube look there. I've seen cracks where the strap is welded on.
Modern header gaskets are great but of course the black carbon trail may show where your leak is.
If that doesn't work to find it if you can have someone break torque the car a little in a completely dark garage you might see fire from where it's ticking. Be careful you don't get run over.
Modern header gaskets are great but of course the black carbon trail may show where your leak is.
If that doesn't work to find it if you can have someone break torque the car a little in a completely dark garage you might see fire from where it's ticking. Be careful you don't get run over.