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Thread: Knock retard on 110 octane at start up?

  1. #1
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    Knock retard on 110 octane at start up?

    So I decided to put 3 gallons of 110 octane gas into an 1/8 of a tank to see if it improved my start up knock. It doesn't seem to matter what tune I use, I still get the knock. The posted histogram shows 9* retard and at that time it's in CL with good LTFT and Lambda is with 2%. Is this just false knock? I don't have any problems with headers touching my frame or loose metal. I've even tried pulling a bunch of timing to see if it helped and it did not. Once the car is fully warm, it doesn't do any more idle knock except like.1 if I rev a bit in neutral. Bottom end is stock with HE cast pistons.
    Any ideas?

    cam : 231/248 .617"/.595" 120+5

    Thanks for looking

    110 octane knock retard test.hpl
    Knock at idle.hpt
    Last edited by marksrig; 04-21-2020 at 07:45 AM. Reason: wromng attachment

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    Damn that's weird. How does it do going down the road? Something has to be bangin around... 110 and less spark its gotta be false? Is the engine noisy?
    14 GMC sierra 5.3

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    Quote Originally Posted by MrFixIt86 View Post
    Damn that's weird. How does it do going down the road? Something has to be bangin around... 110 and less spark its gotta be false? Is the engine noisy?
    Actually it sounds fine and runs sweeeet on the 110. It's just the startup log is crap. I put my old tuners MAF tune in that he did and it was about the same. I'm thinking of piston slap but these are cast pistons so I'm not sure. I'm not a great tuner or even good for that matter, but I think knock is caused by bad gas, too lean, too much spark advance or false readings from piston slap or noise such as headers on the frame. I'm a bit at a loss right now. There is no knock after warm up anywhere in the tune so that's strange and makes me think piston slap on over sensative knock sensors. Car has 14,200 miles on it.

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    That would definitely bother the shit outta me! Hydraulic lifters I assume? It seems like some kind of "knock" or something rattling. Going off of very limited information from you it seems like something is rattling cold and the tolerance gets tighter when things are warmed up. Piston slap comes to mind I guess. If you pull timing and have high octane theres gotta be something mechanical setting the KR sensors off. IDK man doesn't sound like a tuning problem though, i'd look into mechanical issues.
    14 GMC sierra 5.3

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    So yea, LSA supercharged stock bottom end, stock heads and rockers too. LTH no cats so maybe a little noisy, CAI , stage 3 cam bunch of cooling mods, injectors and stuff.

  6. #6
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    Knock sensors are just noise sensors. So based on your mods and no tune posted it is a guessing game

    Timing moves to much during idle. This causes the SC to rattle the Isolator Coupler. So could be knock in the blower
    LTH contact with other metal will cause this.
    "Stage 3" cams usually cause this but hard to know because we do not have the specs.
    Bad tuning causes this
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  7. #7
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    Quote Originally Posted by jsllc View Post
    Knock sensors are just noise sensors. So based on your mods and no tune posted it is a guessing game

    Timing moves to much during idle. This causes the SC to rattle the Isolator Coupler. So could be knock in the blower
    LTH contact with other metal will cause this.
    "Stage 3" cams usually cause this but hard to know because we do not have the specs.
    Bad tuning causes this
    The tune is added to the original post, but as I said before, I get this same thing happening with this tune and my MAF tune from another tuner. No headers touching and my isolator is a solid Metco. Thanks for looking it over.Knock at idle.hpt
    Last edited by marksrig; 04-20-2020 at 11:48 PM.

  8. #8
    Advanced Tuner jsllc's Avatar
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    So knock sensors are stock. That is going to cause some of this. Most likely the idle tuning that was done in combination with a solid isolator is causing the knock. You have some large timing swings at idle that are tring to compensate for the wrong air adjustments that were made. Fix those and add 10% to your knock sensors and see.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  9. #9
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    Quote Originally Posted by jsllc View Post
    So knock sensors are stock. That is going to cause some of this. Most likely the idle tuning that was done in combination with a solid isolator is causing the knock. You have some large timing swings at idle that are tring to compensate for the wrong air adjustments that were made. Fix those and add 10% to your knock sensors and see.
    Thanks, I will look at those. I guess I should've mentioned what cam. BTR stage 3 PD cam. 231/248 .617"/.595" 120+5 so I'm thinking it should be able to have better idle characteristics seeing as overlap is basically 0.

  10. #10
    Advanced Tuner jsllc's Avatar
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    So here are some things to think about. If engine displacement is the same and there is no overlap on cam, why is there a need to add over 20% to air to make it idle?

    If you want help here you have to help those to help you. Need a list of all mods in detail please. Right down to plug changes.

    You do not even mention if the e67 is really in a 2014 ZL1. If it is then this tune is not correct. Your OL fueling is off and your CL fueling is off as well. Points to MAF not being tuned after mods. And if someone told you to just run SD don't. There is no such thing on an e67. It is VVE which is virtual VE. That is a mathematical representation of a VE table meant to use in case of MAF failure. So go back to the stock tune. Make SURE that the car is mechanically sound. Copy over your injector data after validating it is correct. Copy over your current MAF. As for WOT timing, if you are certain the car was right before you can copy the scaling high and low octane tables over as well. Fix the MAF taking into account injector tip temp (I have many posts on this) Once the MAF is right adjust idle. Idle air not timing. Once you are certain MAF is right work on idle timing if needed. Then there are the hundred other areas that need addressing, but only after these are correct. FYI if you can do all of this on 91 with no ethanol. If you do not have an ethanol sensor get one and fix the tune so that it know how to adjust timing based on ethanol content. Always run the same fuel from the same place while tuning.

    log.png
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  11. #11
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    It is in the 2014 ZL1
    This is just my running list of stuff I bought or installed. Most has nothing to do with performance. This isn't my original tune and was one that someone gave me to play with. I thought it worked better than the tune my tuner did that was a 100% MAF. It also had 9* of KR at idle and it was tuned by a "pro" with 20+ years GM experience on a dyno so I guess we get what we pay for. I work so time to tune is limited. I'll report how your advice works out. As I said in the previous post, I'm not a great or even good tuner, but I've messed with it enough to be sure how to keep it from blowing up, just not good at the fine polishing details.

    BTR stage 3 cam
    BTR .660 springs spring kit and titanium retainers.
    3 bolt cam gear with ARP bolts
    GM Performance timing chain
    LS2 chain damper
    BTR 5/16 chromoly pushrods
    BTR v2 Rocker trunnion upgrade kit
    Griptek upper pulley 2.50" w/hub
    Dayco 10% overdrive harmonic damper
    ARP balancer bolt
    HD Greenback belt K080670HD
    Speed Engineering 1-7/8 headers
    DEI header wrap kit
    Cat delete
    Stage8 Header bolts & locks
    ACDelco exhaust gaskets
    ID850 injectors
    Rotofab cold air intake
    Roto-fab hx reservoir
    Rotofab big gulp
    169 deg. Mishimoto Thermostat
    Afco heat exchanger w/ fans
    Reinforced intercooler
    Elite Engineering catch can
    Seperate clutch reservoir
    Metco solid isolator
    oil pickup tube girdle
    NGK #3690 spark plugs
    Phastek w/w remote bottle
    AEM wideband gauges
    Aerotech obd2 gauge
    Autogauge gauge pillar
    NPP exhaust 3 way mode switch
    Dyno tuned
    Skip shift eliminator
    Flowtie
    Jack pads
    Stow N Show license plate bracket
    BMR toe rods
    BMR trailing arms
    JMS Boost a Pump

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    111019 AS FOUND.hpt
    Here was my original MAF tune. I think this is a wreck. The injectors aren't even setup. This was what I ran before adding the 10% lower and BAP.
    I can't understand why there is a value in the 0.0 cell in the MAF Hz.

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    stock idle air kr.hpl

    stock idle air and spark kr.hpl

    So attached are 2 startups. The first I put the idle airflow areas back to stock, the second is the same but I put idle spark to stock and it's not really a cold start.

    The cold start on the idle air only was good but there's still KR. My thinking was to try putting idle spark to stock next since its more retarded. Well it started but as you can see it idled low for a short bit before coming up. KR is still present. Yes I know fueling and all else is the same. It's raining here and I just wanted to see what this would do.

    I guess it helped to stabilize spark from jumping around but only helped the KR somewhat.

    What's your thoughts?

  14. #14
    Advanced Tuner jsllc's Avatar
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    These all require tune changes:
    BTR stage 3 cam
    Griptek upper pulley 2.50" w/hub
    Speed Engineering 1-7/8 headers
    Cat delete
    ID850 injectors
    Rotofab cold air intake

    Metco solid isolator - This can cause false knock

    JMS Boost a Pump - Can cause issues. ZL1 has voltage boosting already for fuel pump through FPCM
    Skip shift eliminator - This can be done in the tune

    Phastek w/w remote bottle - what is this?

    What are your goals for the car? hp/tq
    What boost are you seeing?
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  15. #15
    Advanced Tuner jsllc's Avatar
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    Quote Originally Posted by marksrig View Post
    stock idle air kr.hpl

    stock idle air and spark kr.hpl

    So attached are 2 startups. The first I put the idle airflow areas back to stock, the second is the same but I put idle spark to stock and it's not really a cold start.

    The cold start on the idle air only was good but there's still KR. My thinking was to try putting idle spark to stock next since its more retarded. Well it started but as you can see it idled low for a short bit before coming up. KR is still present. Yes I know fueling and all else is the same. It's raining here and I just wanted to see what this would do.

    I guess it helped to stabilize spark from jumping around but only helped the KR somewhat.

    What's your thoughts?
    Did you add the 10% to the KR tables?

    Please post the tune that was in the car at the time of the last log.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  16. #16
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    I didn't adjust the KR yet. I just had time to do the first 2 test. I figure desensitizing will work, but I rather find out why first if possible. If I can take the 10% from 1000 Rpm to idle then that might be what I have to do. I like the stock air flow for sure. I'm still trying to get my stock tune from my tuner. He responded but it sounded like he wanted to give me someone else's 2014 stock tune and not my VIN specific one. I'm only licensed for my car. He didn't reply the second time.
    Attached is the tune with idle air and idle spark at stock. Once again, it idled and started lazy with stock spark.

    see attached

    testing stock idle air and stock idle spark.hpt
    Last edited by marksrig; 04-23-2020 at 12:35 AM.

  17. #17
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    that one is easy. Metco solid isolator
    Last edited by jsllc; 04-23-2020 at 08:25 PM.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  18. #18
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    So SC rattle.
    I?m glad you responded to the thread. I didn?t think the stock idle air would work so well. I?m going to take the stock tune once I get it and start from scratch like you said, instead of trying to modify previous tunes. I think less is more in my case.
    Thanks

  19. #19
    Advanced Tuner jsllc's Avatar
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    The original isolator had a spring to make it smoother at idle. No lash. Now you made it solid. The SC gears are the victim.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  20. #20
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    Quote Originally Posted by jsllc View Post
    The original isolator had a spring to make it smoother at idle. No lash. Now you made it solid. The SC gears are the victim.
    Yes, the spring was rusty and starting to chew into the shaft. There always seems to be a give and take when modifying cars. Looks like rain for the next several days so no tuning. I got new tires yesterday so today I wanted to see how those hooked. Much better without fear of a blowout.