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Thread: General Help Tuning?

  1. #1
    Electronic Ignition!
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    Question General Help Tuning?

    First, let me say I've done many hours of research, including searching for answers on this site, to try to figure out everything I can myself. I apologize if I ask a question that's already been answered, but I did my best to figure it out on my own (a big part of my problem is that I often find two conflicting answers).
    That being said, I still feel like my grasp of tuning is incomplete, and I haven't been making much progress on getting my BLMs to 128.

    My process is this: I upload the latest bin to my Ostrich 2.0 emulator, allow the car to enter closed loop, and then go for about a 25min drive to datalog. With my dad in the passenger seat reading TunerPro's BLM history table, I do my best to max out sample counts (I have my ADL histo set to max at 50) in as many cells as I can. Typically, that will look something like shown below.
    History table.PNG

    Then, using Trimalyzer (I used to use a homebrewed Excel spreadsheet but found Trimalyzer to work better) with the filters shown below, I modify my VE tables, and I inspect Trimalyzer's knock map, dropping a degree or two of timing in cells where knock is seen. Using Excel, I also note my average BLM and BLM standard deviation. I then upload this newest BIN to my ECM, and repeat the process.
    Trimalyzer filters.PNG

    The issue is, my BLMs don't seem to be getting any better - in fact, my last datalog showed I am pretty far off, when just a few BIN revisions ago I was pretty close (average of 127.2, standard deviation of 2). BIN history table is shown below, with the most recent at the bottom. What am I doing wrong?
    BIN history.PNG


    • Is smoothing VE tables necessary? Even my most successful tune's lower VE map looked pretty jagged (seen below). Part of me wants to get it nice and smooth, but the other part of me thinks the complex engine dynamics could well result in the actual VE of the engine varying in such a seemingly unsteady manner.
    • How good is good enough, in terms of BLMs?
    • Do I need to disable EGR? None of the guides I read mentioned this, but I just saw a post today saying it must be disabled.
    • Does ambient air temperature have a major effect on BLMs?
    • Is dialing in my spark table crucial to pass smog?
    • On that note, is there anything specific I need to fiddle with to reduce emissions?
    • Which tables do I need to mess with beside main spark advance and VE?
    • Does $8D pull data from VE cells surrounding the one it's in like some other ECMs?
    • Given that CA gas has 10% ethanol in gas, should I change target AFR to 14.13:1?

    VE Map.PNG

    My car:
    1990 Corvette base model with ZF6 transmission
    383 TPI, AFR heads, Lunati Voodoo 262/270
    1227727 ECM, $8D mask

    Thanks in advance.
    Last edited by 90Vette; 06-04-2017 at 08:50 PM.

  2. #2
    Fuel Injected! steveo's Avatar
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    The issue is, my BLMs don't seem to be getting any better - in fact, my last datalog showed I am pretty far off, when just a few BIN revisions ago I was pretty close (average of 127.2, standard deviation of 2). BIN history table is shown below, with the most recent at the bottom. What am I doing wrong?
    why would you tune something already tuned?

  3. #3
    Electronic Ignition!
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    So you think that was good enough? I thought I had heard every cell should be 128 +/- 2 or 3, and I wasn't there yet.

    Interestingly, I just revisited that tune but got less promising data, showing an average of 126.7 and standard deviation 4.7.
    Last edited by 90Vette; 06-04-2017 at 10:19 PM.

  4. #4
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    That VE table is a big mess, should be smoothed for the cell interpolation to work correctly.

  5. #5
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    Smoothed it and made a few tweaks last night, think I'm happy with this.
    Final VE.PNG
    BLMs.jpg




    Quote Originally Posted by 90Vette View Post
    • Do I need to disable EGR [for tuning VE]? None of the guides I read mentioned this, but I just saw a post today saying it must be disabled.
    • Does ambient air temperature have a major effect on BLMs?
    • Is dialing in my spark table crucial to pass smog?
    • On that note, is there anything specific I need to fiddle with to reduce emissions?
    • Which tables do I need to mess with beside main spark advance and VE?
    • Given that CA gas has 10% ethanol in gas, should I change target AFR to 14.13:1?
    Anyone got answers?

  6. #6
    Fuel Injected!
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    1. EGR doesn't HAVE to be disabled to tune, but it helps to elliminate as many variables as possible, EGR being another variable that may skew readings.
    2. IAT/MAT is used to compensate for air density, and unless the IAT compensations tables are 100% correct you will see variations in BLM depending on air temperature and humidity.
    3. Spark advance has a great impact on HC / NOx balance.
    4. Basically, too much NOx - give it more fuel, too much HC - lean it out.
    5. For general driveability, those two would suffice, with higher overlap cam you should lowe O2 switching points at lower airflows to avoid unnecessary enrichment caused by overlap. PE tables are also important after part throttle is dialed in.
    6. You can do that, but it will skew you already tuned VE table. If the engine runs correctly it doesn't really matter.

  7. #7
    Electronic Ignition!
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    Thanks for the help.

    Which table do you refer to as O2 switching points? "Fast O2 Rich/Lean Threshold Vs. MAP"?

    EDIT:
    I was looking at my PE tables, and I realized that on the stock BIN for a '90 Corvette the PE AFR ranges from (assuming a realistic coolant temp) 9.96:1 at 3600 RPM to 13.25:1 at 1200 RPM. I've heard that 12.5:1 is usually ideal for making power, but the stock tune stays below 12:1 from 2800 RPM up. Why would GM have this so rich, and should I change it to 12.5:1?

    PE Table.PNG
    Last edited by 90Vette; 06-05-2017 at 02:34 PM.

  8. #8
    Fuel Injected! steveo's Avatar
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    I've heard that 12.5:1 is usually ideal for making power
    that totally depends.

    max power on many engines is closer to 13:1, and some engines like more fuel in some regions, that's why dyno tuning results in best power gain rather than widebanders simply trying to hit a particular AFR.

    also despite the base fuel map being close, intended target is often different from actual achieved target... even if you get all your trims perfect, power enrichment might still not be what you expect.

    a major mfr like gm usually aims for somewhere between 11:1 and 12:1 on stock calibrations to prolong engine life during abuse at the expense of a minimal power loss, and also as a safety threshold to keep the engine alive in event of mechanical problem, sensor inaccuracy, inconsistent fuel quality, engine production differences, etc.

  9. #9
    Electronic Ignition!
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    That makes sense, thanks. Without access to a dyno or a WB O2, what AFR in PE would you suggest I aim for?

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  11. #11
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    First off, I'm ecstatic to say my car just passed smog with flying colors! I'm not sure how much having a new cat played into that, but I was surprised that with a bigger cam and homebrewed tune I passed so easily. Thank you to everyone that helped me!

    Now that it's smogged, I have a driveability issue to work out - once hot, the engine randomly dies - but after that I'll be right back to playing with PE. I think I'll add in 2-3 of PE timing and drop the PE AFR to 11.75:1 to start, then slowly work my way up in AFR and down in timing until I find the sweet spot. Does that sound good?

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  13. #13
    Electronic Ignition!
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    Actually, ICM is at the top of my list! Glad you confirmed that.
    I also am considering the ignition switch, but the cut-outs seem to correlate more with a long run-time than with bumpy roads.

    Do you have any preferred replacements? I'm considering replacing the coil too if I can find one that doesn't hit on my hood.

  14. #14
    Fuel Injected!
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    I had a similar problem. The dielectric grease dried out and the ICM would over heat. I cleaned things up, re-installed the ICM with new grease and the problem went away.

  15. #15
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    Replaced the ICM, and no dice. Also replaced the ign. switch and tried running with the tach wire disconnected. This is pretty annoying.

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