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Thread: Getting a ton of knock after a cam install on a LT1 Camaro

  1. #1

    Getting a ton of knock after a cam install on a LT1 Camaro

    Like is says. Installed a cam/headers on a 17 LT1 Camaro. Cars seems to drive fine and was dialed in on the street. Idle still needs a small tweak but its getting there. Cam is a VVT3 TSP cam and as soon as it passed 4k at wot the knock enters and rises. I turned down the sensors a bit and even changed to a cooler NGK Iridium plug. Still knocks and isn't making the power I was hoping for. You can even feel it chug a big up top. Any one else run into an issue like this? I'm hoping the chugging I feel up top is all the timing being pulled. We are seeing 12 degrees of kr by 5600rpm. Before 4k nothing. Car doesn't seem to be misfiring. Plugs and wires are good. Car is entering pe and seeing a 12.76afr and the afr error looks great. Timing is around 15-20 but when I pulled timing it didn't change anything. Any ideas?

  2. #2
    Senior Tuner Ben Charles's Avatar
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    It’s false... I can get low 20s on good 93 just fine

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  3. #3
    Whats the best way about going about this other then ordering the Plex system for $1200. Octane?

    Would the kr make the car chug like that?

    What's a safe level to turn the knock sensors down too.

  4. #4
    have you played with injection timing, Im still learning the Gen 5 stuff but it seems like people report knock if the injection timing is off.

  5. #5
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    The knock can be false knock. Try zero out static retard table it often reports knock retard to pull timing on indivual cylinders. Normally the table is filled between 5600rpm to 6400rpm in the LT1 camaros.
    Normally I zero it out on cammed Gen V because it may make you chase your tail.

  6. #6
    Adjust torque tables. Most likely false

  7. #7
    Quote Originally Posted by ZincGT View Post
    have you played with injection timing, Im still learning the Gen 5 stuff but it seems like people report knock if the injection timing is off.

    Yes, I added injection timing during wot.

  8. #8
    Senior Tuner Ben Charles's Avatar
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    Quote Originally Posted by JASON11WS6 View Post
    Yes, I added injection timing during wot.
    Be careful with that on a cam with any type of overlap

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  9. #9
    Quote Originally Posted by Ben Charles View Post
    Be careful with that on a cam with any type of overlap
    It's only 5 degress overlap 235/239, .645"/.635", 116 LSA. I raised it some but it didn't seem to effect anything. Car is still making around 10-12 degrees of knock. static retard has been zeroed, all the burst knock has been zeroed and I have turned the knock sensors down. Car has good 93 in it and made an excellent dyno pass before we installed the cam. Cam went in fine with no real issues.

  10. #10
    Here is my last scan/tune file if anyone wants to take a crack at it.
    Attached Files Attached Files

  11. #11
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    Quote Originally Posted by JASON11WS6 View Post
    Here is my last scan/tune file if anyone wants to take a crack at it.
    Could be TCS or TQM , try to disable ECM 295 and max ECM 2850 & 2851 .

  12. #12
    While I don't have a solution to offer (sorry....still wrapping my head around Gen V stuff), thought I'd throw an observation out there from looking at the provided scan.

    Looking at the 02 voltages, they virtually overlay each other up to the point that the knock event occurs. At that point they diverge for the remainder of the pull. This to me would indicate that whatever is occurring may be confined to 1 bank of cylinders.....possibly not a tune related issue, but it would seem that the 2 banks begin operating differently at that point.

    Like I said, my Gen V experience is limited, so take it with a grain of salt.....it may be nothing. Just hoping to help resolve the issue.

  13. #13
    I've been checking for anything banging or rattling around and the headers are suspect. One tube runs about 1/16-1/8" away from the steering shaft and another is 1/16" at most away from the motor mount. You guys think maybe that could cause false knock if they are rubbing against the headers like that?

  14. #14
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by JASON11WS6 View Post
    I've been checking for anything banging or rattling around and the headers are suspect. One tube runs about 1/16-1/8" away from the steering shaft and another is 1/16" at most away from the motor mount. You guys think maybe that could cause false knock if they are rubbing against the headers like that?
    As has been mentioned, this is not knock or ping noise related.

    I recommend exploring torque table/management issues (not talking about limiters).

  15. #15
    As in the virtual torque tables? I heard they pulled timing on those tables but have not run into it yet. Would it come across as knock?
    Last edited by JASON11WS6; 07-11-2019 at 03:31 PM.

  16. #16
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by JASON11WS6 View Post
    As in the virtual torque tables? I heard they pulled timing on those tables but have not run into it yet. Would it come across as knock?
    you can check for sure by setting your knock sensors to 32 and see if it stops, of course be careful and don't leave it this way. if it shows knock like that then it isn't from noise (knock sounds) but something in the ECM.

    you might also note that the Fuel System Tab has tables for High Flow lift pump commanded pressure and at 4000 RPM it goes from forced Normal Pressure to forced high Pressure. maybe you are having a commanded vs actual lift pressure situation if you get sudden large retard right at 4k consistently. That doesn't really behave like a normal in cylinder detonation IMO.

  17. #17
    So my rookie mechanic installed the VVT block off plug wrong and we replaced the entire cam gear (it unwound). Car is no longer knocking. Just letting you guys know in case you hear it again. It was a mechanical issue. Sorry for the run around.
    Last edited by JASON11WS6; 07-14-2019 at 11:16 AM.

  18. #18
    Senior Tuner Ben Charles's Avatar
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    Good to hear

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    Quote Originally Posted by JASON11WS6 View Post
    So my rookie mechanic installed the VVT block off plug wrong and we replaced the entire cam gear (it unwound). Car is no longer knocking. Just letting you guys know in case you hear it again. It was a mechanical issue. Sorry for the run around.
    Daaaaaaammmmnnn!

  20. #20
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    Thanks for the feedback, this is how all threads need to end.