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Thread: s10 with lq4 + ls3 heads, sd tune lean spots especially at WOT

  1. #1
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    s10 with lq4 + ls3 heads, sd tune lean spots especially at WOT

    06 lq4 stock bottom end
    TSP ls3 ported heads milled to 64cc
    TSP .629/.615 225/235 114lsa cam
    LS3 Intake
    Speed Density Tune no MAF

    After the speed shop tuned it and handed it over to me I immediately thought it was running bad so I decided to look into things myself by buying hp tuners. I recorded an 8 minute session with a 40-80 mph pull in second gear and a couple of other lighter pulls. I noticed under WOT and even other times there is quite a bit of RED on the 02 chart which has me worried.

    I was hoping someone could view the log and let me know their thoughts on how lean it might be running or anything else they notice. Basically anything to point me in the right direction.

    Cruise-log and tune uploaded.
    Attached Files Attached Files

  2. #2
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    your maf is still there, disable it in engine diagnostics,DTC first 3 should be error on first. They have no mil

  3. #3
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    Thank you for the tip. I Changed those 3 to "MIL on first error"

    Looks like that caused the engine light to come on. Unfortunately looks like lean condition from the 02s remain.
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  4. #4
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    Just uncheck the SES box for the MAF codes.

    It honestly looks like nothing was touched for fueling. If you took a stock files VE table and compared it to your current VE table all you would notice is that yours is slightly lower than a stock one. The table and the curve look pretty much exactly the same.

    How is your fuel pressure, is it steady at 58psi even under load?

    Do you have a wideband o2 sensor so you can monitor real time air fuel ratio's??

    Looks like they just made sure it could idle and did some power pulls. Zero time taken to get fueling correct. Your idle is okay but part throttle is mess where it goes lean per the fuel trims. Then a few time are WOT your o2 sensors take a nose dive under 100mv showing that it's way lean. For sure it's because the VE is not tuned correctly and you may have a fuel pressure drop there as well.

    Power enrichment should be set up different too. Raise the MAP kpa enable to 80kpa, lower the rpm delay from 5,000 down to 1,500. I would change the cold/hot enable from 0-3,000rpm to 50% instead of 64 as well.


    The logs are missing lots of stuff too. Add knock retard, injector pulse width avg, cylinder airmass, commanded AFR or commanded EQ ratio.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  5. #5
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    Okay I hooked up a fuel pressure gauge. At WOT there is a drop from 60psi to about 54-55 psi. (Some say this is normal, some say it isn't)

    I haven't touched PE yet, but I did add some fuel in response to the LTFT which doesn't seem to help too much. After every test drive the LTFT keeps asking for more and more fuel.

    I also got a tad bit of knock at 75-80 kpa 2400-2800 rpm. At that spot there is a sudden drop in fueling in the VE table, however its still more fuel than it was before so that confuses me.

    Latest log uploaded, along with the added logging on the left side.
    Attached Files Attached Files
    Last edited by Neeseius; 4 Weeks Ago at 03:09 PM.

  6. #6
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    Here's a much better log with some WOT runs. The good news is it looks like under WOT the lean condition is much much better. The bad news is there is this newfound knock retard, from .2 to 1.5 degrees at WOT. It seems the timing has been retarded quite a bit because of it (I may be on low octane table now). I don't understand why adding fuel and fixing a lean condition would cause KR.

    I added a new chart with bank 1 and 2 pulse width and cylinder air mass.
    Attached Files Attached Files

  7. #7
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    There is something going on with bank 2, especially during WOT pulls. See the LTFT on Bank 2 is 9-10% higher than Bank 1? During the first WOT pull, the left bank averaged around 900mV O2 sensor output. the right bank went very low. This is usually indicative of a misfire or lack of fuel on the low bank. I'd start by shooting each header tube on that bank with a temp gun. I'll bet one will be colder than the rest.

  8. #8
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    You were right! Cylinder 6 was 100 degrees cooler than the rest. Turned out to be a burnt spark plug wire.
    For some reason the ECU is not capturing any of the misfires, even if I unplug a coil pack.

    After replacing the wire things are feeling and looking better now. I am hoping the knock I was seeing was cylinder 6. I didn't see more knock in the short 5 min drive I recorded but the timing is still in the low octane table it seems.

    Things overall look much better.
    Attached Files Attached Files
    Last edited by Neeseius; 3 Weeks Ago at 06:59 PM.

  9. #9
    Looks like the misfire monitor is disabled.
    03 Z06 stock.......for now
    05 Siearra 5.3 daily
    I have realized that tuning is a rabbit hole. No problem diving down this hole, in fact I jumped willingly. Just want to avoid hitting every ugly rock or root on the way down it.