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LS3 Grandsport with Headers - tune & timing questions

Old 07-13-2018, 10:04 AM
  #21  
schpenxel
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Originally Posted by truth.b View Post
I bought a wideband and installed it today and so far here are my take aways:
- idle AFR is bouncing from low 14.xx to high 15.xx before it roughly somewhat stabilizing @ 14.5ish
- a few half to full throttle stabs showed an AFR of 12.2
- with cruise set on a relatively flat road the AFR moved around alot
It's supposed to bounce around like that when cruising or at idle, that's on purpose. Should average right around 14.7 but will go a few percent above and below that.

Narrowband O2's can only really say whether it's rich or lean, but not how much, so the computer goes back and forth adding and subtracting fuel to make the O2's "swing" from rich to lean, rich to lean, rich to lean, etc.
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Old 08-12-2018, 04:31 PM
  #22  
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Update:

Its been about a month and I've been able to learn a lot and start the process of getting the tune where I want it. The first thing I did was revert the min timing table back to stock and completely cleared up my surging and weird sub 1200RPM engine issues. Afterwards I decided to go back to all the stock timing tables and completely start over by first dialing in the VE table. This took a couple weeks and about 2 tanks of fuel because I wanted to be thorough and all the time ended up being worth it. Part throttle, initial tip-in, heel-toe transitions and cruising have all greatly improved at times it feels like an actual throttle cable vs the stock laggy drive-by-wire setup.

New Questions:
- Other than knock and running lean what are some other ways improper tunning can hurt an engine? I ask because I've been mostly paying attention to AFR and knock to determine if what I'm doing is hurting something in the engine.
- Also how lean can a engine run without damage? specifically what would the instant number be and what would to long for x seconds number be? So far I've tying to keep everything around 14.68 while running in Speed Density VE during logging.
- When tuning my VE table my target was for the computer to run rich about 2-5% ... i.e. show (-2 thru -5) values for most of the cells between idle and 3/4 throttle (~70kPa). Is this a reasonable spec or should I have tire to get it to run richer or leaner?
- After tuning the VE table and tunning everything back on my car's LTFT run between -2% thru +2% on high humidity high 80F day when its 83F or below the LTFT tend to run between -5% thru -2%. Does this seem appropriate?
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Old 08-12-2018, 04:50 PM
  #23  
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Overall what are you guys thoughts on the following logs?


The following are my STFT based on a 1hr drive using the latest version of my VE table.
STFT in Speed Density mode:




The following are my LTFT based on a 1hr drive using the latest version of my VE table copied into my full tune.
LTFT in normal driving mode:




The following are my LTFT based on using same VE table as above but on a hotter day.
LTFT in normal driving mode:

Last edited by truth.b; 08-12-2018 at 04:56 PM.
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Old 08-13-2018, 09:48 AM
  #24  
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Looks fine to me. I might make some small adjustments to the spots that are 5% or more off but that would be about it for those areas.
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Old 08-13-2018, 02:46 PM
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Originally Posted by schpenxel View Post
Looks fine to me. I might make some small adjustments to the spots that are 5% or more off but that would be about it for those areas.
I've been logging around the clock for the last couple of weeks without changing anything and on average between the rain and heat I'm +/-2% on LTFT's. Also I changed KR recovery tables from stock values to 2.0 (pics listed) and now my next question is what are your thoughts on the knock that I have circled in the picture below. FYI: KR reference line is -1.5* Ideally I want KR to be 0 understand steady state driving but clearly the sensors are picking up something. Can these small sub 1* fluctuations be ignored?

Stock KR Recovery Rate


Modified KR Recovery Rate:





Last edited by truth.b; 08-13-2018 at 02:48 PM.
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Old 08-13-2018, 02:58 PM
  #26  
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I wouldn't go anywhere near that high. I'd multiply stock by maybe 2 or 3 but not x 40 or whatever that works out to

Are you logging just plain "knock retard" or total knock retard or the generic parameter for knock retard or what? Need to make sure it's just plain knock retard and say no when it asks if you want to use the generic version of that PID or you'll be picking up other stuff
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Old 08-13-2018, 06:00 PM
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Originally Posted by schpenxel View Post
I wouldn't go anywhere near that high. I'd multiply stock by maybe 2 or 3 but not x 40 or whatever that works out to

Are you logging just plain "knock retard" or total knock retard or the generic parameter for knock retard or what? Need to make sure it's just plain knock retard and say no when it asks if you want to use the generic version of that PID or you'll be picking up other stuff
I'm logging "knock retard" (PID:2630) under Engine > Spark & Ignition > Retard not the generic parameter. I reworked my KR Recovery Rate table and I'll pay more attention to see if other events are causing the knock to show up.
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Old 08-13-2018, 07:34 PM
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k cool, just making sure. The generic one picks up burst KR and some other stuff so not really what you'd want
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Old 08-15-2018, 10:09 AM
  #29  
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Originally Posted by truth.b View Post
I leave for and vacation this weekend but when I get back I'll order HP Tuners.

My plan:
  1. change nothing and log many different driving situations
  2. if things are all good change the min timing table back to stock
  3. work on learning how .. then dialing in the MAF/VE tables
  4. make smoothing/reduction in timing decision based on the above

What do you guys think about my preliminary plan? Any advice or further guidance is greatly appreciated.
Sometimes I get confused, but if you don't have HP Tuning equipment at this point in time. How did you get access to all the tables you show above?
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Old 08-15-2018, 12:08 PM
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Originally Posted by jim2092 View Post
Sometimes I get confused, but if you don't have HP Tuning equipment at this point in time. How did you get access to all the tables you show above?
When I made my initial post I had my tuner give me all the tunes he did on my car via thumbdrive, that way I could track the changes. Since that post I've acquired the new HP Tuners OBDii module and I've basically been researching, logging, and tuning around the clock since about mid July. Best money I've spent on the car since I purchased it 5 years ago.
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Old 08-30-2018, 12:17 PM
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You are on the right track - and that initial tune was terrible!
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Old 10-19-2018, 11:37 PM
  #32  
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First of all,

I want to thank everyone that encouraged me and gave me advice on how to rework the tune on my car. It took some time and patience but I am VERY pleased with the overall results. I went to the dyno last week and car was steady as a rock. I didn't know which smoother to use so I've posted Smoothing=0 and Smoothing=3; but basically my car makes a little more than 415RWHP & 410ft-lbs of torque consistently. Over the course of an hour I checked my tune and ended up with about 15 runs car stayed with 5 horsepower run to run. For future reader purposes I'll include more detail sometime next week but I just wanted to put this up for right now.

Smoothing = 0



Smoothing = 3


Last edited by truth.b; 10-22-2018 at 01:25 PM.
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