Cant get the AirFlowPerRev and CombinedFT right

Posted by cabot2g, Jun 11, 2012
Tuning & Engine Management - 4G63 EPROMS, ECU, MAF, knock, EGT, wideband, datalogging, fuel trims, etc. Read this Forum's Strict Guidelines.

  1. cabot2g

    cabot2g Proven Member

    DSM Profiles:
    1
    Joined:
    Feb 13, 2012
    Posts:
    68
    Likes Received:
    0
    Cabot, Arkansas
    I keep adjusting the injector deadtimes trying to get the CombinedFT down to 1% or less but I cant get it to budge. Its staying around 16.8% and my wideband is reading 17:1 - 19:1

    As an example, when my wideband is reading 17.3:1 the AFRatioEst is showing 12.5:1

    I have the AirFlowPerRev around 0.24 - 0.25 gm/rev

    7 bolt 2L
    evoIII 16g
    Stock injectors
    Stock fuel pump
    2g MAF

    Boost leak test, resolved all leaks but the BOV. Have to do somthing with the leaking TurboXS.

    Any suggestions?
    #1
  2. snowborder714

    snowborder714 Moderator

    DSM Profiles:
    1
    Joined:
    Oct 15, 2006
    Posts:
    11,736
    Likes Received:
    86
    Downingtown, Pennsylvania
    1. Post a log.
    2. Are you sure your wideband is logging the correct value?
    #2
  3. cabot2g

    cabot2g Proven Member

    DSM Profiles:
    1
    Joined:
    Feb 13, 2012
    Posts:
    68
    Likes Received:
    0
    Cabot, Arkansas
    I was saving the file and you posted before I could get it uploaded... LOL

    LC-1 wideband, air calibrated and Link set to LC-1 wideband.

    Wideband is located in the front O2 housing and running simulator in link.

    Attached Files:

    #3
  4. My1GLaser

    My1GLaser Proven Member

    DSM Profiles:
    1
    Joined:
    Dec 4, 2006
    Posts:
    1,394
    Likes Received:
    12
    Bartow, Florida
    Your STFT is pegged positive because your O2 is reading very lean.

    Isn't it more conventional to simulate narrowband frt O2 by putting the WB in the rear O2 bung and lock the rear O2 voltage? I would say, you either have a big exhaust leak before your WB or maybe the sensor is bad. Some people don't have good luck with the WB that close upstream. It might be more for longevity reasons, but this is the 2nd WB sim issue I've seen in a couple days.
    #4
  5. cabot2g

    cabot2g Proven Member

    DSM Profiles:
    1
    Joined:
    Feb 13, 2012
    Posts:
    68
    Likes Received:
    0
    Cabot, Arkansas
    Is there a way to test the O2? Its brand new, doesn't have more than 20 miles on it.
    #5
  6. snowborder714

    snowborder714 Moderator

    DSM Profiles:
    1
    Joined:
    Oct 15, 2006
    Posts:
    11,736
    Likes Received:
    86
    Downingtown, Pennsylvania
    #6
  7. cabot2g

    cabot2g Proven Member

    DSM Profiles:
    1
    Joined:
    Feb 13, 2012
    Posts:
    68
    Likes Received:
    0
    Cabot, Arkansas
    I dont think its my O2 Sensor, I will calibrate it again. I will check the gaskets at the manifold to turbo and turbo to O2 housing.
    #7
  8. My1GLaser

    My1GLaser Proven Member

    DSM Profiles:
    1
    Joined:
    Dec 4, 2006
    Posts:
    1,394
    Likes Received:
    12
    Bartow, Florida
    Where is your BOV leaking? Is your BOV recirculated? I'm not familiar with the turbo XS model. If it is vented to atmosphere and leaking at the valve seat, then you could very well be that lean at idle depending on how bad the leak is.

    Are you running inexplicably rich under boost?
    #8
  9. cabot2g

    cabot2g Proven Member

    DSM Profiles:
    1
    Joined:
    Feb 13, 2012
    Posts:
    68
    Likes Received:
    0
    Cabot, Arkansas
    Its a VTA and leaks as soon as I put any pressure on it with a boost leak test.

    Havent ran much boost yet. Its a new engine and breaking it in.


    ******************************************************************

    Update...

    Decided to recalibrate the wideband, once calabrated I was able to get the numbers to react to my changes. Also removed the leaking bov and plugged it just to get the idle dialed in.

    I found out what knocked my o2 sensor off, when the car is running I didnt have the ground on the battery secured. It came off and caused the car to stall for just a fraction of a second. But it caused the CEL to throw, checked to see what it was and it was the front o2 sensor.

    After that it was acting just like it did before calabrating. So tomorrow I will calabrate it again and make sure the ground is secured.

    Im getting a little idle surge but I think Im on the right path.

    http://www.dsmtuners.com/forums/attachment.php?attachmentid=140558&d=1339557468
    Last edited: Jun 12, 2012
    #9

Share This Page