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  1. #1
    LTX Member


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    Brian Rota
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    1995 firebird
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    Default Running poorly over near 3000 rpm

    Sorry for repost I put it in the wrong section
    Hello I have a 1995 Firebird with LT1.
    A few weeks ago I was driving my car got stuck in some rain (which I didnt do often). The car started to run a little funny.
    Next day it cut out when I was driving it after a few minutes I was able to restart it.
    Doing some research it sounded like the opti maybe got wet. So I replaced the opti the seals and water pump.
    I drove it and when it was warmed up it started to cut out when I stepped on it.
    it also seems to have trouble going over 3000 rpm when the issue is happening even when rev it.
    Fuel pressure looked good.
    Scanned with Scan9495 and eehack no codes other than maybe some from running with sensors unplugged but clear and have not come back.
    Not sure what to look for in the app besides that.


    New ICM and MAF were installed
    Carquest/Advanced Auto opti was installed


    See the video it starts at about 11 seconds my foot is almost to the floor.


    Both datafiles can be opened with excel
    Attached Files Attached Files

  2. #2
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    Mike Storm "Stormy"
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    Default

    Opti vent hose in good shape? My hose was old it would close up on full throttle making the Opti miss fire do to the cap touching the rotor probably not your issue though.

    It's not how fast you mow. It's how you mow fast.



    1995 Trans Am - CAI - TB coolant bypass - Headers & Performance Muffler - Poly mounts - stock LT1/A4 - 13.3 1/4 - 1.9 60 foot , driven daily.
    2008 C6 Corvette LS3 Snake charmer Ram Air intake. 6 Speed Switchable mild to wild exhaust.
    2002 Silverado LT Extd Cab Z71 5.3 A4 Composite Bed Stock

  3. #3
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    Weston Ketner
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    1995 trans am
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    Default

    Mine was a shit msd coil....

    Sent from my Z963VL using Tapatalk

  4. #4
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    Brian Rota
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    Default

    Thank you I was able to blow air into the lines so I do not think that was it but good though!!

    I ran a new scan with scan9495 I figured out my index issue was because I didn't save the file it was just the default collection file.
    here is a new file incase anyone knows what to look at.
    Last edited by brota; 09-13-2017 at 06:16 PM.

  5. #5
    LTx Guru


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    Fred
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    1994 Formula - SOLD
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    SOLD - GONE TO A (VERY) GOOD HOME ! - 94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / CC solid roller / TH400+GearVendors OD / 4.11 Strange 12-bolt / 300-shot N2O / Spohn Suspension / roll bar / MoTeC M48 Pro engine management system /a few other odds 'n ends.

  6. #6
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    Brian Rota
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    1995 firebird
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  7. #7
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    Default

    The coil be the last thing I try.
    I am not doing the opti again, I will sell the car first
    Last edited by brota; 09-13-2017 at 07:25 PM.

  8. #8
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    Gary
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    Default

    Everything looks pretty normal as far as I can see. Fred is the real expert, I learned anything I know from him. But if I were you, I would try to check the fuel pressure when this happens. No codes for that.

    By the way, it doesn't matter when you save the log file, either as its being logged, or after the scan is over. The files will be the same except for the name. The original file was definitely a transmission data log.

    1998 Trans Am - LS1/A4 - all stock and almost all original - one owner - driven daily.
    Author of Scan9495, free pc apps 93-95 LT1,94/95 L32: http://ltxtech.com/forums/showthread...light=scan9495

  9. The Following User Says Thank You to GaryDoug For This Post:


  10. #9
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    Brian Rota
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    Default

    Great thank you.
    I did test fuel pressure but not sure it was when it was happening.
    It was where it should be and there was no leak down.
    I will try and test it again after I do the coil.

    If it is the opti again it is going in storage for a bit.

  11. #10
    LTx Guru


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    Fred
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    Default

    Not sure how you managed to end up with 5 identical copies of the log in one file..... there is about 3 minutes of useful closed loop operation. Still need to look at it in detail, but the numbers are all over the place. At idle, the LTFT's are 160, indicating the PCM is pouring in at least 25% extra fuel to maintain the A/F ratio. High LTFT's in Cell 10 (147/149) adding extra fuel. Might tend to suspect low fuel pressure. But then there's Cell 11 at 122/122, and Cell 14 at 121/123.

    But then when you open the throttle any decent amount (doesn't matter whether the car is moving/under load, or if it's just sitting still) and you're revving the engine, both O2 sensors go pig rich (900 - 1000+ mV) and stay there even after you close the throttle. If it was in PE mode, that might make sense, but most of the time it is in PE mode for only a fraction of a second.

    Never saw anything like this one before.... but give me some more time to try and figure out why it's so screwed up.

    Have you pulled any spark plugs to check condition?

    Check the fuel pressure anyway, and respond with numbers. At idle, vacuum comp line attached; at idle, vacuum comp line disconnected/plugged; out on the road under load, as high an RPM as you can reach. Check for wet fuel in the vacuum line. Pull the EVAP line off the throttle body and see if there is any wet fuel in that.
    Last edited by Injuneer; 09-14-2017 at 04:05 PM.
    SOLD - GONE TO A (VERY) GOOD HOME ! - 94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / CC solid roller / TH400+GearVendors OD / 4.11 Strange 12-bolt / 300-shot N2O / Spohn Suspension / roll bar / MoTeC M48 Pro engine management system /a few other odds 'n ends.

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