Page 1 of 2 12 LastLast
Results 1 to 10 of 18

Thread: Knock at WOT

  1. #1
    Junior Member
    Join Date
    Jan 2010
    Posts
    12

    Default Knock at WOT

    I'm just starting to log data and I noticed I'm getting some KR at WOT. Also injector duty cycle shows 86% that seems high for a car with only intake manifold, throttle body, and cat-back exhaust mods.

    My PCM is on a stock tune so what could be causing this KR? I attached the log file, let me know what you guys think. Thanks.

    Updated: Added two extra logs one with less knock.
    Attached Files Attached Files
    Last edited by Epox4life; February 5th, 2010 at 12:50 PM. Reason: Updated

  2. #2
    Lifetime Member Chevy366's Avatar
    Join Date
    Oct 2006
    Posts
    1,603

    Default

    Not unusual to get knock in a stock tune at WOT , stock tunes are so generic and just close enough for all .
    2005 1500 HD , Custom OS3 SD tune .
    2006 Trailblazer
    Dinosaurs and Plants gave their lives so that we may drive , long live fossil fuel .

  3. #3
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    4,935

    Default

    Some I6 TrailBlazers have up to 5-6 degrees of knock!!! I have logs to prove it (somewhere...)
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

  4. #4
    Lifetime Member mr.prick's Avatar
    Join Date
    Nov 2006
    Posts
    3,195

    Default

    There's something not right about that log, was it filtered before it was saved?
    LTFTs are high and positive during PE (7%) and
    AD1&2 are stuck @ 3.4v-3.8v so no way to add WBO2 data if you had one hooked up.
    Are stock tunes that bad?
    512k RoadRunner Firmware 12.14R
    FlashScan V2 Bootblock V2.07.04 Firmware V2.07.22 EFILive V7.5.7 (Build 191) V8.2.1 (Build 181)
    LC-1 WBO2

    _________________________________________________

  5. #5
    Junior Member
    Join Date
    Jan 2010
    Posts
    12

    Default

    Quote Originally Posted by mr.prick View Post
    There's something not right about that log, was it filtered before it was saved?
    LTFTs are high and positive during PE (7%) and
    AD1&2 are stuck @ 3.4v-3.8v so no way to add WBO2 data if you had one hooked up.
    Are stock tunes that bad?
    Completely stock tune and that log was not altered in anyway. Stock tunes are pretty bad commanded AF is 11.7!

    Quote Originally Posted by Chevy366 View Post
    Not unusual to get knock in a stock tune at WOT , stock tunes are so generic and just close enough for all .
    Thats good to know, looks like I'm going to have to do a lot more reading and work on a tune for my car. Thanks guys!

  6. #6
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    11.7 might be cat overtemp protection kicking in.

  7. #7
    Lifetime Member mr.prick's Avatar
    Join Date
    Nov 2006
    Posts
    3,195

    Default

    That is stock PE ratio for a '98.
    The positive LTFTs during PE points to more fuel being needed or
    maybe Ethanol in the tank.
    I filled up the other day and saw my LTFTs go positive,
    making me believe I got more than I bargained for at the pump.

    I have heard that 97-98 have inferior KR sensors too.
    512k RoadRunner Firmware 12.14R
    FlashScan V2 Bootblock V2.07.04 Firmware V2.07.22 EFILive V7.5.7 (Build 191) V8.2.1 (Build 181)
    LC-1 WBO2

    _________________________________________________

  8. #8
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    Oh, I see... I'll have to look more closely at a 98 file...

    The 98's suffer from KS problems, constistant 4° KR... there is an upgraded KS and sub-harness from GM.

    Altho his KR looks like it is sawtooth shaped indicating it might be real...

    I have read about overly-rich spark knock, but I don't think this is the case.

  9. #9
    Junior Member
    Join Date
    Jan 2010
    Posts
    12

    Default

    Quote Originally Posted by mr.prick View Post
    That is stock PE ratio for a '98.
    The positive LTFTs during PE points to more fuel being needed or
    maybe Ethanol in the tank.
    I filled up the other day and saw my LTFTs go positive,
    making me believe I got more than I bargained for at the pump.

    I have heard that 97-98 have inferior KR sensors too.
    I am in the north east where we all have 10% ethanol at every pump, it sucks.

    How much will having 10% ethanol in the gas change the tuning process? What things should I look out for because of this?

    Added two more log files at the first post.

    I was thinking doesn't torque reduction in the stock tune pull timing on shifts? Is that done by using KR or could it cause KR to happen?
    Last edited by Epox4life; February 5th, 2010 at 12:57 PM.

  10. #10
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    28,403

    Default

    TR just reduces timing to prevent knock... it doesn't cause KR to happen, and it doesn't use KR to reduce timing...

    The value you see for the KR pid is in response to knock/noise being detected by the knock sensors... the PCM determines how intense it is and sets KR which is subtracted from the final spark advance (i.e. SPARKADV reduces by KR amount).

Page 1 of 2 12 LastLast

Similar Threads

  1. Knock Retard GM.KNKRET vs Retard Due to Knock GM.KR
    By Gelf VXR in forum General (Petrol, Gas, Ethanol)
    Replies: 3
    Last Post: March 9th, 2008, 04:18 AM
  2. Knock after COS #3 install, but never had knock before
    By CRU SS N in forum Custom Operating Systems
    Replies: 12
    Last Post: June 15th, 2007, 10:07 PM
  3. 1:50,75 AFR-- no knock ??
    By germanvette in forum Gen IV V8 Specific
    Replies: 6
    Last Post: May 6th, 2007, 04:40 PM
  4. Knock knock.... who's there? KR
    By Whippled 496 in forum General (Petrol, Gas, Ethanol)
    Replies: 24
    Last Post: September 24th, 2006, 10:59 PM
  5. Can't get rid of knock
    By jsttry in forum General (Petrol, Gas, Ethanol)
    Replies: 9
    Last Post: May 11th, 2005, 12:56 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •