Results 1 to 11 of 11

Thread: Lean condition when reving

  1. #1
    Tuner in Training
    Join Date
    Mar 2010
    Location
    Sheldon, Ia
    Posts
    12

    Lean condition when reving

    A little info on my car, 2001 z28 Camaro. 232/238 comp cam. full bolt ons. auto... I have had help tuning the car through a friend of mine and I also rented the dyno locally to dial it in on the dyno. It ran great then started to have a stumble when going wot from a stop. I noticed shortly after that it does the same thing when I rev. basically what happens is when I rev it will go extremely lean and sputters. (pegs the wideband at 22.4) then around 2000 rpm it goes normal. but once I let off and the rpms fall and goes back to idle it stumbles and tries to die but usually it catches and will idle normal but then the afr will be in the mid 11 range idling and takes a while to go back to stoich. this is only when I rev it hard. if I ease into it then it wont have this issue. I did have one code come up and was a o2 bank 1 sensor 1 low voltage. I cleared the code and haven't had the code come back. im thinking its a bad o2 sensor but I wanted to see if anyone else had this type of issue. and if it sounds like its tune related or if its a symptom of o2 sensors...

  2. #2
    Tuner in Training
    Join Date
    Mar 2010
    Location
    Sheldon, Ia
    Posts
    12
    here is my tune
    Attached Files Attached Files

  3. #3
    Tuner in Training
    Join Date
    Mar 2010
    Location
    Sheldon, Ia
    Posts
    12
    Noone has any input?

  4. #4
    Advanced Tuner Texas_WS6's Avatar
    Join Date
    Mar 2008
    Location
    Odessa, Texas!
    Posts
    383
    Do you have a log to show us? We will need that as well.
    2002 WS6 TA, 408, L92 heads, Holley Modular High Ram, 120# injectors, Fast 92mm tb, 9.5:1 compression with Ross Pistons, built 4L80E with T-Brake, Circle D 4C Billet 245mm stall, Moser 9" with 3.70 gears. Front mounted GT-88 with Front Mount Intercooler, 3BarSD tuning by me.
    DIY Dual Walbro 340 fuel pumps.

  5. #5
    Advanced Tuner Texas_WS6's Avatar
    Join Date
    Mar 2008
    Location
    Odessa, Texas!
    Posts
    383
    I want to see what the STFT's are doing.
    2002 WS6 TA, 408, L92 heads, Holley Modular High Ram, 120# injectors, Fast 92mm tb, 9.5:1 compression with Ross Pistons, built 4L80E with T-Brake, Circle D 4C Billet 245mm stall, Moser 9" with 3.70 gears. Front mounted GT-88 with Front Mount Intercooler, 3BarSD tuning by me.
    DIY Dual Walbro 340 fuel pumps.

  6. #6
    Tuner in Training
    Join Date
    Mar 2010
    Location
    Sheldon, Ia
    Posts
    12
    Quote Originally Posted by Texas_WS6 View Post
    I want to see what the STFT's are doing.

    k here is a log. I also noticed when I rev it that it has like 5-6*kr

    and here is a video of it

    http://s176.photobucket.com/user/syc...e4690.mp4.html
    Attached Files Attached Files
    • File Type: hpl 1.hpl (24.5 KB, 19 views)

  7. #7
    Advanced Tuner Texas_WS6's Avatar
    Join Date
    Mar 2008
    Location
    Odessa, Texas!
    Posts
    383
    What config did you use? Post it so we can see what you are seeing. Do you have a WB on it as well?
    2002 WS6 TA, 408, L92 heads, Holley Modular High Ram, 120# injectors, Fast 92mm tb, 9.5:1 compression with Ross Pistons, built 4L80E with T-Brake, Circle D 4C Billet 245mm stall, Moser 9" with 3.70 gears. Front mounted GT-88 with Front Mount Intercooler, 3BarSD tuning by me.
    DIY Dual Walbro 340 fuel pumps.

  8. #8
    Tuner in Training
    Join Date
    Mar 2010
    Location
    Sheldon, Ia
    Posts
    12
    Quote Originally Posted by Texas_WS6 View Post
    What config did you use? Post it so we can see what you are seeing. Do you have a WB on it as well?
    hmmm not sure but I can post my config if that helps... and yes I have a wideband on it... also watch the video I posted so you can see what the rpms are doing and the wb is seeing too
    Attached Files Attached Files

  9. #9
    How long did it run fine for after the tune, miles? One time I was chasing what I thought were tuning demons and found that my plugs were fouled. I replaced the iridium's with some copper tops (what they had at the time) and it ran much better.

    Other than that, I noticed that your o2's seem to be saying the same thing as the wideband. When I graph the o2 voltages you can see a pattern in the throttle blips where the voltage drops on the rpm rise.

    Assuming that the tune was running great and nothing has changed I would look for something mechanical like a vacuum leak maybe? Spray some ether around and see if you get a quick rise in rpm at idle. Thats's my .02 for you, good luck!
    2020 Camaro ZL1 1LE - M6

  10. #10
    Tuner in Training
    Join Date
    Mar 2010
    Location
    Sheldon, Ia
    Posts
    12
    see that's the thing is I never hit it from a stop or revved it hard. if I ease into it then it will be fine. but when I rev it hard here are the things it does

    1. instantly goes max lean on my wide band and sputters till about 2000 rpm. then on up after that it revs fine...
    2. when I let off and the rpms come back to idle it tries to die and will surge up and down some. the afr will then be 11.5-12.0 range. and if I then try to rev it hard it will be fine and wont go lean.

    like I said tho it doesn't do this if I just ease into it...

    now as far as mechanical I have checked for vacuum leaks by spraying starting fluid around all the intake, vacuum lines, injectors, and intake after the maf. everything was good there, I changed o2s and spark plugs. I have a digital fuel pressure gage and have a racetronix pump and hotwire and it holds strong at 65 psi fuel pressure the entire time...

    basically it seems to me like there is something im missing in the tune that when the throttle is opened it doesn't add the fuel that is needed for the rush of air so it goes lean

  11. #11
    Ok, have you tried adjusting the throttle follower airflow table? Maybe try lowering the throttle % from 23.5 and up. As others have suggested here, if you have the pro interface hookup your wideband as part of your scan so the afr can be seen with your other values. Also might want to add the IAC in the scan so if you try lowering your throttle follower airflow table you can see the result of that.

    How are your IAC at idle? typically a good target is around 40 or so.
    2020 Camaro ZL1 1LE - M6