Page 1 of 2 12 LastLast
Results 1 to 20 of 28

Thread: Getting KR under hard acceleration

  1. #1
    Tuner in Training
    Join Date
    May 2019
    Posts
    48

    Getting KR under hard acceleration

    Let me start with saying I'm pretty new to tuning, and started learning on a 5.3 swap I'm doing in a 2000 S10 Blazer. It's running/idling fine, but I just recently got it driveable and am trying to work out the kinks, so there could be glaring issues in my scan log/or tune that I'm just not experienced enough to notice.

    5.3 with a with small compression bump(4.8 flat top pistons) summit 8719 cam -209 int./217 exh. with an LS6 intake. Seems to pull OK but take off seems weak. I'm getting a lot of knock retard when going WOT. I cannot hear anything bad from the motor during runs. It sounds great. Does this seem like a fuel issue? Just 87 octane in it right now, but I'm worried I have something else going on?

    Any and all help very much appreciated.
    Attached Files Attached Files

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Get a wideband o2 sensor as soon as possible. You must be able to monitor the real time air fuel ratio's, there is no guessing with this stuff.

    You're missing a lot of good data in your logs too. I don't see commanded AFR or lambda, no injector pulse width avg for both banks, cylinder airmass is missing, no wideband o2 sensor data.

    Pump 87 isn't helping with a camshaft and compression bump. Run 89+ octane at a minimum if you ask me.

    Make sure fuel pressure is steady too, should always be around 58psi. Then use the wideband data to tune both the MAF and VE to correct the fueling.

    Based on the o2 sensor readings at full throttle, it's looking pretty lean. They can't be trusted 100% but on a healthy setup with good sensor they will report in the ball park. The roughly .800mv is pretty low, typically I see 890-930mv.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Advanced Tuner 2therock's Avatar
    Join Date
    Jun 2009
    Location
    N. GA
    Posts
    530
    I just played back your log monitoring spark retard live in the chart seeing 5 & 7? being pulled here and there with smaller numbers around also.. So at least your sensors are working. Do the same and go to those cells in your tune and see if some crazy numbers are happening and pull some out in those areas.

    But yes, get a WB o2 setup and run better fuel. I would do better fuel and log again first.
    2013 Dodge Charger R/T Plus, Stock 5.7L, Edelbrock E-Force Stage 1, 3.25" Pulley, 450-HP 459-TQ.
    Corsa Sport CatBack, 3.06:1 Wavetrac, Dual Fans, 1-7/16 Radiator, Mopar Oil Cooler
    2005 Radix'd Silverado L33 5.3 ECSB Z71 @ 387-HP 395-TQ

  4. #4
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    I do need a wideband for sure. But here is a dumb question regarding the stock 02s, are they different or vehicle specific? I installed the stock 4.3 sensors.

  5. #5
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Look up the part numbers to be sure.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  6. #6
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    Quote Originally Posted by 2therock View Post
    I just played back your log monitoring spark retard live in the chart seeing 5 & 7? being pulled here and there with smaller numbers around also.. So at least your sensors are working. Do the same and go to those cells in your tune and see if some crazy numbers are happening and pull some out in those areas.

    But yes, get a WB o2 setup and run better fuel. I would do better fuel and log again first.
    The timing map is still stock 1999 5.3 truck. I did take a look, but didn't see anything aggressive there. Maybe PE is coming in late? The only thing I changed there was the EQ ratio to 1.18. That should put me around 12.44 AF.

    I will put some better fuel in and do some more logging. Will look for a wideband as well.

  7. #7
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    put in some 91 octane and logged again with more pids. not really any better.
    Attached Files Attached Files

  8. #8
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Based on o2 sensors again without knowing the real fueling, is possibly way lean. I'd aim for 12.0 until you can get that wideband and make sure fuel pressure is not dropping at full throttle. Bump the PE enable to 80-90kpa and lower the enable rpm down to 1,500 and 60% throttle instead of 70-90%.

    With this setup disabling burst knock by maxing the burst knock enable cylinder air delta table is something I do too.

    I also noticed you installed or put in the tune that it's running 33lb/hr injectors. I don't have a flex fuel tune with me at the moment but did you copy over the rest of the data for those injectors if you did install them??
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  9. #9
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    Quote Originally Posted by 5FDP View Post
    Based on o2 sensors again without knowing the real fueling, is possibly way lean. I'd aim for 12.0 until you can get that wideband and make sure fuel pressure is not dropping at full throttle. Bump the PE enable to 80-90kpa and lower the enable rpm down to 1,500 and 60% throttle instead of 70-90%.

    With this setup disabling burst knock by maxing the burst knock enable cylinder air delta table is something I do too.

    I also noticed you installed or put in the tune that it's running 33lb/hr injectors. I don't have a flex fuel tune with me at the moment but did you copy over the rest of the data for those injectors if you did install them??
    I only changed the flow rate for the flex fuel injectors, should I have changed everything on injector control? I thought I remember reading somewhere at the time that's all that needed changing.

  10. #10
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    At a minimum you must change the injector flow rate, short pulse adder, min injector pulse and offset vs volts.

    Right now the rest of the data is likely incorrect for the flex fuel injectors.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  11. #11
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    OK, fuel pressure seems to stay good during WOT. I copied the flex fuel injector settings from a stock flex fuel tune. I changed the PE as recommended(coming on sooner/12.0AF) Disabled the burst knock by setting to 8g.

    This did make my o2s read richer(closer to 900mv). However the KR is still there. I did notice doing a little brake torque at the beginning there was no KR.(lower engine temp) I then went for a few pulls(lots of KR at WOT, higher engine temps). Then brake torqued again when I got back and the KR was still there.

    At no time have I heard or felt any unwanted knock noise from the engine. Log attached. I could add more fuel during PE and see what happens Other than hot spots in the combustion chamber, what cause temp dependent knock?
    Attached Files Attached Files

  12. #12
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,533
    Bad vibration or rubbing parts.

    Even a pending or current knock sensor code. That last log shows the knock maxing out at 8 degrees a few times. It's fairly common that if you have a pending knock sensor code that it can peg out the knock retard channel to the maximum allowed KR in the calibration.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  13. #13
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    I actually did get a knock sensor p0332 code. While replacing, I noticed a lot of oil in the intake. It's coming from the PCV, which has no valve that I can tell, just an opening in the valve cover. Cleaned out what I could and re-assembled. Went for a test drive and the KR was still there, but occasionally also not there at WOT under load? Could oil be causing my problem?
    Attached Files Attached Files
    2000 S10 Blazer 2WD 5.3L Summit 8719 cam -209 int./217 exh. with an LS6 intake and 4L60E trans

  14. #14
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    I installed a PCV and it seems to have stopped the oil from entering the intake. At first I filled up with 93 octane and added some booster, but that didn't change anything, still reading knock. I have also now noticed by giving it part throttle under high load conditions but not downshifting, it will start running crappy and getting the KR in the log(assuming lean condition). I took a look at my spark plugs and they show a lean condition.

    I know my fuel pressure is staying good during these events, it never dropped below 60 psi, so it must be some other issue that I'm not seeing. At this point I'm just guessing, but even without the WB installed yet, I'm pretty confident it's a lean problem.

    Can someone confirm for me, do those MAF g/s numbers look low? Barely breaking 300g/s during some of these WOT runs. Like maybe it is under reporting the real flow number? Could it also be caused by an intake leak of some kind? I've go no other indication of a vacuum leak though. Any other suggestions about what could cause this?
    2000 S10 Blazer 2WD 5.3L Summit 8719 cam -209 int./217 exh. with an LS6 intake and 4L60E trans

  15. #15
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    I also had another thought about the MAF. I converted my harness to move the IAT into the MAF, as it was originally 2 separate harness plugs. I do get a an IAT reading that make sense, but are there any adjustments required in the tune for this conversion?
    2000 S10 Blazer 2WD 5.3L Summit 8719 cam -209 int./217 exh. with an LS6 intake and 4L60E trans

  16. #16
    Senior Tuner
    Join Date
    Mar 2011
    Location
    Ripley, MS
    Posts
    1,865
    The MAF is reading a little low, however, you've only got an average of 5 or 6 degrees total timing at WOT. If it keeps throwing the knock sensor code, then you'll have to fix them. Alternatively, you can go to those DTC's and change them to No Error Reported. They will still function, but won't max out the timing retard.
    You might also consider getting a good cold air induction system and/or a larger TB. The MAP is dropping from 98kPa down to 93kPa at WOT. This indicates a bit of a restriction in the intake system.
    Once you get that sorted and the AF Ratio and timing dialed in, the MAF will report a higher number.

  17. #17
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    Quote Originally Posted by kevin87turbot View Post
    The MAF is reading a little low, however, you've only got an average of 5 or 6 degrees total timing at WOT. If it keeps throwing the knock sensor code, then you'll have to fix them. Alternatively, you can go to those DTC's and change them to No Error Reported. They will still function, but won't max out the timing retard.
    You might also consider getting a good cold air induction system and/or a larger TB. The MAP is dropping from 98kPa down to 93kPa at WOT. This indicates a bit of a restriction in the intake system.
    Once you get that sorted and the AF Ratio and timing dialed in, the MAF will report a higher number.
    Thanks for the response. I did already change the knock sensor that was throwing the code, and so far, it has not come back. That's when I found oil in the intake. Does it still pull timing at all with the code disabled?

    I do have a large intake/cone filter setup, but am kind of limited for space under my hood(s10 and all).

    It really just seems like I'm missing something obvious, that might have nothing to do with the tune(vacuum leak?), or is definitely being cause by a bad VE/Maf/injector setting that is causing a lean condition at heavy part throttle and WOT. I thought the datalogging would reveal what that is by now, but so far, no joy.
    2000 S10 Blazer 2WD 5.3L Summit 8719 cam -209 int./217 exh. with an LS6 intake and 4L60E trans

  18. #18
    Senior Tuner
    Join Date
    Mar 2011
    Location
    Ripley, MS
    Posts
    1,865
    Here ya go. Make sure you have at least 89 octane in it and give this tune a try.

    99CHEV5.3BLAZER-12-23-19akwmod.hpt

  19. #19
    Tuner in Training
    Join Date
    May 2019
    Posts
    48
    Quote Originally Posted by kevin87turbot View Post
    Here ya go. Make sure you have at least 89 octane in it and give this tune a try.

    99CHEV5.3BLAZER-12-23-19akwmod.hpt
    Thank you very much! Your changes definitely helped it. Log attached.

    Still getting some KR, but not like before. I looked at the changes, but what do you think was the main thing that improved it?

    Part throttle high load is still having some issues. Like 40% throttle in 4th gear. Would that mainly be addressed by WB and VE tuning?
    Attached Files Attached Files
    2000 S10 Blazer 2WD 5.3L Summit 8719 cam -209 int./217 exh. with an LS6 intake and 4L60E trans

  20. #20
    Senior Tuner
    Join Date
    Mar 2011
    Location
    Ripley, MS
    Posts
    1,865
    Quote Originally Posted by RedLT4 View Post
    Thank you very much! Your changes definitely helped it. Log attached.

    Still getting some KR, but not like before. I looked at the changes, but what do you think was the main thing that improved it?

    Part throttle high load is still having some issues. Like 40% throttle in 4th gear. Would that mainly be addressed by WB and VE tuning?
    I actually added timing across the entire RPM range. However, I made changes to bring the PE in a lot quicker.
    Try this revised version. I pulled a couple of degrees from the 3200-4000 rpm range in order to reduce KR. WB tuning needs to happen next.

    Out of curiosity, what spark plugs are you running?

    99CHEV5.3BLAZER-12-23-19akwmod2.hpt
    Last edited by kevin87turbot; 01-08-2020 at 10:03 PM.