Results 1 to 6 of 6

Thread: Barometric pressure swing

  1. #1
    Fuel Injected!
    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    52

    Barometric pressure swing

    I am getting barometric pressure readings 80 to 95 causing tuning to be inconsistent, is there an adjustment to help with this?
    Reading is stable when logging but from one day to the next is where I see the swing.
    Last edited by Dom; 10-20-2018 at 07:23 PM.
    1993 Chevy Blazer TBI Vortec long block 5.7
    16168625 BDJZ 46mm TB 18 PSI fuel
    Camshaft, Hydraulic Roller Tappet, Advertised Duration 288/308, Lift .431/.451
    Chevrolet Performance Vortec TBI Intake Manifold
    shorty's, y-pipe and 3" full boar muffler

  2. #2
    Fuel Injected! donf's Avatar
    Join Date
    Apr 2017
    Location
    Oregon
    Posts
    275
    I think the real baro pressure varies with the weather patterns, at least it does here. So wouldn't a change from day to day be normal?

  3. #3
    Fuel Injected!
    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    52
    I know that the weather will have an affect on the real baro Pressure, but is the swing that large normal?
    1993 Chevy Blazer TBI Vortec long block 5.7
    16168625 BDJZ 46mm TB 18 PSI fuel
    Camshaft, Hydraulic Roller Tappet, Advertised Duration 288/308, Lift .431/.451
    Chevrolet Performance Vortec TBI Intake Manifold
    shorty's, y-pipe and 3" full boar muffler

  4. #4
    Fuel Injected! donf's Avatar
    Join Date
    Apr 2017
    Location
    Oregon
    Posts
    275
    Can you track the real changes with weather info online and compare them to what you are seeing? I have seen failing map sensors give faulty baro readings but not very common. There is a good map test in the factory manuals. You could run through that and see if anything strange shows up.

  5. #5
    Fuel Injected!
    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    52
    I will give that a try
    1993 Chevy Blazer TBI Vortec long block 5.7
    16168625 BDJZ 46mm TB 18 PSI fuel
    Camshaft, Hydraulic Roller Tappet, Advertised Duration 288/308, Lift .431/.451
    Chevrolet Performance Vortec TBI Intake Manifold
    shorty's, y-pipe and 3" full boar muffler

  6. #6
    Fuel Injected!
    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    52
    Up date

    Never Tested the map sensor

    If I pause for 1 sec before I crank the engine over giving the map sensor to self calibrate I get a repeatable reading.


    If I don't pause or get a miss start, readings are not so much repeatable and needs to be restarted and a longer pause before cranking.

    Bad battery (old) I never need to crank the engine over for more then 2 secs.


    5.0 to 15.0 would be about the swing, not sure if this would make a big swing in a tune.
    Last edited by Dom; 07-30-2019 at 02:39 AM.
    1993 Chevy Blazer TBI Vortec long block 5.7
    16168625 BDJZ 46mm TB 18 PSI fuel
    Camshaft, Hydraulic Roller Tappet, Advertised Duration 288/308, Lift .431/.451
    Chevrolet Performance Vortec TBI Intake Manifold
    shorty's, y-pipe and 3" full boar muffler

Similar Threads

  1. Injector Pressure
    By bgott in forum GM EFI Systems
    Replies: 4
    Last Post: 03-16-2018, 09:03 PM
  2. Replies: 6
    Last Post: 06-05-2017, 06:18 AM
  3. fuel pressure
    By ony in forum Gear Heads
    Replies: 2
    Last Post: 04-27-2013, 09:48 PM
  4. O2 Swing Points
    By EagleMark in forum OBDII Tuning
    Replies: 5
    Last Post: 01-15-2013, 11:19 PM
  5. TBI Adjustable Pressure Mod
    By mudbuggy in forum GM EFI Systems
    Replies: 38
    Last Post: 09-29-2011, 02:24 AM

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
  •