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

Thread: LQ4 With LSA Supercharger goes lean

  1. #1
    Senior Member
    Join Date
    May 2011
    Posts
    184

    Default LQ4 With LSA Supercharger goes lean

    I have a LQ4 with an LSA Supercharger, on a COS tune. The car starts and runs, but on heavy throttle, even at idle, the AFRs go extremely lean. The motor has 80lb Dekka injectors, and a Sloppy Mechanics stage 2 Cam, with a 3 Bar MAP sensor. There is no MAF. The motor will rev nicely, but not when the throttle is depressed quickly, and the SC builds boost. Am I missing something with the config?
    Attached Files Attached Files

  2. #2
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    795

    Default

    Your using cathedral heads with the adapters for the LSA or are you using rectangle port heads?

  3. #3
    Senior Member
    Join Date
    May 2011
    Posts
    184

    Default

    Yes, I have adapter plates and am aware of the issues. I was not aware adapter plates, and the flow restriction would cause the motor to almost stall. I aware of a lean tip in, but not almost total engine cut out.

  4. #4
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    795

    Default

    Yea it will act completely dumb. And it will take forever to get all the small hickups worked out of it.
    Those are bad enough that i wont tune one ever again haha.

    I gotta get on the other laptop to see your tune.

  5. #5
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    795

    Default

    Which 3 bar map?
    What is the fuel pressure at and is it vacuum referenced?
    Have you done any fuel tuning? Your VE tables dont look right.
    Last edited by nonnieselman; November 12th, 2025 at 07:12 PM.

  6. #6
    Senior Member
    Join Date
    May 2011
    Posts
    184

    Default

    Quote Originally Posted by nonnieselman View Post
    Yea it will act completely dumb. And it will take forever to get all the small hickups worked out of it.
    Those are bad enough that i wont tune one ever again haha.

    I gotta get on the other laptop to see your tune.
    Yeah. I have heard different stories regarding ironing out the hickups.

  7. #7
    Senior Member
    Join Date
    May 2011
    Posts
    184

    Default

    Quote Originally Posted by nonnieselman View Post
    Which 3 bar map?
    What is the fuel pressure at and is it vacuum referenced?
    Have you done any fuel tuning? Your VE tables dont look right.
    - GM 12592525 Map Sensor
    - Vacuum referenced FPR, set at 58psi.
    - No tuning done yes, just a LQ4 VE table with 5% added.

  8. #8
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    795

    Default

    (Map Data wrong, VE needs to be tuned, checking on injector data).

    Dont even try to make boost or rev it up till you have the vacuum VE sorted out.
    Ill fix the issues i found and get you a startup tune.
    Do you have a wideband?

    Are the injectors Legit Deka 80s?
    or they off Ebay or somewhere really cheap?

    Tall or Short Injectors?
    Last edited by nonnieselman; November 13th, 2025 at 04:29 AM.

  9. #9
    Senior Member
    Join Date
    May 2011
    Posts
    184

    Default

    Quote Originally Posted by nonnieselman View Post
    (Map Data wrong, VE needs to be tuned, checking on injector data).

    Dont even try to make boost or rev it up till you have the vacuum VE sorted out.
    Ill fix the issues i found and get you a startup tune.
    Do you have a wideband?

    Are the injectors Legit Deka 80s?
    or they off Ebay or somewhere really cheap?

    Tall or Short Injectors?
    Yes, I have a wide Band, and it hooked up to my flashscan via serial. I got my short dekka's from Ebay's KM Racing store, and they came with a flow sheet.

    Ill look for your mods.

  10. #10
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    795

    Default

    I wouldnt trust those.
    Ill find the LS3 Deka 80 data and get something fixed up for you.

Page 1 of 2 12 LastLast

Similar Threads

  1. LQ4 lean on start up.
    By pormgb in forum Gen III V8 Specific
    Replies: 15
    Last Post: June 25th, 2024, 09:47 AM
  2. LSA supercharger table
    By Eng.LSX in forum E37, E38 & E67 PFI ECM's
    Replies: 5
    Last Post: April 30th, 2014, 11:57 AM
  3. PROBLEMS with tip in lean LSA
    By Brad Brand in forum Gen III V8 Specific
    Replies: 1
    Last Post: September 24th, 2013, 01:05 PM
  4. LSA Lean during PE transition
    By Meister in forum E37, E38 & E67 PFI ECM's
    Replies: 10
    Last Post: March 19th, 2013, 03:28 PM
  5. L5 harrop supercharger goes lean???
    By miguelc in forum IL6,IL5,IL4 Atlas Engines - P12 PCM
    Replies: 1
    Last Post: August 11th, 2011, 02:26 PM

Posting Permissions

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