Results 1 to 8 of 8

Thread: Cold Engine runs Too Rich, which tables to adjust?

  1. #1
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    43
    Posts
    70

    Cold Engine runs Too Rich, which tables to adjust?

    I'm trying to find out what tables or scalars affect AFR when the engine is cold.

    I have PCM 16197427 with bin BJYL and mask OE ( I think I got all those words right). It runs rich when cold, very rich, like 8.0, fogging unburned gas out the tailpipes. Seems to stay rich even when in closed loop until it warms up, like a minute later at least. The AFR will slowly increase once it starts to warm up. Even in closed loop, when it's cooler outside my BLMs are 121 ish, and when it gets hotter they are like 133 ish, so I don't know if it's purely a open loop thing or not.

    I can't find a table for temperature vs AFR
    There is a section for Choke Part to Drive AFR Parameters, but I don't think that affects it.
    I have been searching and read about "Choke- Time Out AFR vs. Coolant Temp" in another thread, but my mask doesn't seem to have that.
    I found some stuff for cranking and cold start, but I don't know how long after start that would affect anything.
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

  2. #2
    LT1 specialist steveo's Avatar
    Join Date
    Aug 2013
    Posts
    4,007
    $0E is heavily documented and has a crap ton of parameters, in fact so many parameters you should be lost about which one to use rather than not being able to find one

    there are probably 100 defined tables that control open loop and cold start AFR and its decays

    if you don't have such parameters, i have a hunch you're using a crappy XDF. make sure you're using the 'advanced' xdf. see this thread:

    http://www.gearhead-efi.com/Fuel-Inj...Information-OE

    and use parameter 'category' view so you can figure out what tables are for what

    for starters how bout make the necessary adjustment in 'open loop afr vs temperature vs vacuum' or if it's just for initial start, 'choke afr vs temperature' and 'choke afr decay time vs temperature'

  3. #3
    Fuel Injected! CDeeZ's Avatar
    Join Date
    May 2012
    Location
    Jokelahoma
    Posts
    422
    BJYL bin is $0D mask, not $0E.

    I had the exact same issue recently, I'll post my bin tomorrow for you to look at. The open loop afr table that steveo mentioned was crazy rich in the stock $0E bin I started out with. I leaned out that table and also leaned out the VE cells around where it idles to fix that issue.

  4. #4
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    43
    Posts
    70
    Quote Originally Posted by CDeeZ View Post
    BJYL bin is $0D mask, not $0E.
    I must be using a BJDR based bin then. I also tried BNKN at one time I think.
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

  5. #5
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    43
    Posts
    70
    Quote Originally Posted by steveo View Post
    $0E is heavily documented and has a crap ton of parameters, in fact so many parameters you should be lost about which one to use rather than not being able to find one

    there are probably 100 defined tables that control open loop and cold start AFR and its decays

    if you don't have such parameters, i have a hunch you're using a crappy XDF. make sure you're using the 'advanced' xdf. see this thread:

    http://www.gearhead-efi.com/Fuel-Inj...Information-OE

    and use parameter 'category' view so you can figure out what tables are for what

    for starters how bout make the necessary adjustment in 'open loop afr vs temperature vs vacuum' or if it's just for initial start, 'choke afr vs temperature' and 'choke afr decay time vs temperature'
    You were exactly right, I had a crappy xdf. I got the advanced xdf now. Much better. I found the open loop afr vs temperature vs vacuum table and it seems to be exactly what I needed. Thank you so much! I look forward to seeing what else is there now that wasn't before.
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

  6. #6
    Fuel Injected! CDeeZ's Avatar
    Join Date
    May 2012
    Location
    Jokelahoma
    Posts
    422
    BJDR is the one I started out with on my recent 350 4L80 build. The Open Loop AFR table is stupid rich in that table. Try looking at one from a big block bin of the same mask and copy it over. If you need to lean out the idle more, figure out what cell it idles in on the VE tables, then lean out that cell and the surrounding 9 or 12 cells.

    Also look at Open Loop Idle Lean Limit.
    Last edited by CDeeZ; 02-21-2019 at 12:14 AM.

  7. #7
    LT1 specialist steveo's Avatar
    Join Date
    Aug 2013
    Posts
    4,007
    just so you know too...

    hen it's cooler outside my BLMs are 121 ish, and when it gets hotter they are like 133 ish, so I don't know if it's purely a open loop thing or not.
    that's kind of normal, if we're talking about a large temperature variation. some ECMs do good IAT compensation and some dont. you might make sure your IAT is located in factory-like location

  8. #8
    Fuel Injected! brian617's Avatar
    Join Date
    Apr 2013
    Location
    Arkansas
    Age
    45
    Posts
    711
    Quote Originally Posted by steveo View Post
    just so you know too...



    that's kind of normal, if we're talking about a large temperature variation. some ECMs do good IAT compensation and some dont. you might make sure your IAT is located in factory-like location
    No IAT in $0E or $0D unless modified.
    89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
    95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
    05 Outback XT 2.5L turbo gas auto

Similar Threads

  1. 91 5.7 TBI runs very rich - 1227747 $42
    By ravex in forum GM EFI Systems
    Replies: 4
    Last Post: 08-09-2017, 08:14 PM
  2. 5.7 vortec runs rich
    By dhworkin in forum GM EFI Systems
    Replies: 20
    Last Post: 05-14-2017, 09:17 PM
  3. Too rich after cold start?
    By BigBanks78 in forum GM EFI Systems
    Replies: 6
    Last Post: 03-09-2017, 07:27 PM
  4. Replies: 1
    Last Post: 06-10-2016, 06:24 AM
  5. Ultra rich at cold start???
    By jameslleary in forum GM EFI Systems
    Replies: 25
    Last Post: 11-20-2012, 03:35 PM

Bookmarks

Posting Permissions

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