Results 1 to 9 of 9

Thread: LQ4 flooding during crank, no fire, commanded afr crazy rich

  1. #1
    Tuner in Training
    Join Date
    Dec 2011
    Posts
    16

    LQ4 flooding during crank, no fire, commanded afr crazy rich

    Car was running/starting before winter. LQ4 swap with bigger injectors, 2.5bar MAP sensor. When cranking the commanded AFR is crazy low (3-5:1 ratio range) and the injector pulse is 30+ msec, and keeps flooding cylinders to the point that spark plugs won't even ground and spark.

    Originally when I went to start it up a couple days ago, the MAP sensor was reading maxed out (210kpa), and I discovered the black ground wire in the MAP plug on the harness wasn't connected to ajune 8 no start on tune 56.hplTune56.hpt ground.

    Also, this swap has had gauge output issues from the beginning.. tach/speedo outputs from PCM never worked when connected properly to Speedhut gauges. And MIL light test "on" has never worked.

    Tune and scan of cranking are posted below. I'm thinking there's some screwy internal ground in the PCM that for some reason gave up the ghost over winter, however the car was running well with this tune the last time I drove it in October.

    Thanks for any help/insight guys..

    june 8 no start on tune 56.hpl
    Tune56.hpt
    Last edited by frojoe; 06-08-2013 at 07:24 PM.

  2. #2
    Advanced Tuner blownbluez06's Avatar
    Join Date
    Jan 2008
    Location
    Forney, TX
    Posts
    982
    I don't have time to get into all the problems, but fix your OLFA table. all 1.0 isn't going to catch once you start the motor. Try 1.25 @ 14 degrees from top to bottom click and drag to 140 and interpolate horizontally or change it back to stock and then make it 1.0 from 158 up. Then go to Fuel>General>FA Mult Stage 1 vs time and lower the values in there at your starting temps incrementally until you get the desired result.
    Hsquared racing engines RHS 427, Procharger F2, Moran Billet Atomizer injectors, Alky Control,Mast LS7 heads, Nitrous outlet kit,Tilton quad disc clutch, DSS shaft, RKT56 ZR1 trans, RPM Quaife diff. Built and tuned by yours truly.

  3. #3
    Tuner in Training
    Join Date
    Dec 2011
    Posts
    16
    I did as you suggested, and it's still commanding 4-5:1 afr and just dumping fuel (injector pulse widths 25-30ms).

    jul6 scan4 - tune59, changes to starting fuel as suggested on forum.hpl

    Tune59_tune58 but changing cranking fuel values to stock tune.hpt

  4. #4
    Tuner in Training
    Join Date
    Dec 2011
    Posts
    16
    One more thing.. I can control my MIL light on/off thru the scanner, but with key in ign the MIL light is constantly on, but there aren't any DTC's being reported in the scanner......??

  5. #5
    Tuner in Training cpolaris502's Avatar
    Join Date
    Mar 2012
    Posts
    26
    With the key in, ignition on the MIL light turns on? That is normal with almost any stock car.

  6. #6
    Tuner in Training
    Join Date
    Dec 2011
    Posts
    16
    Does it normally time out? Or only go away once running? I have nothing to compare to with this swap because the previous PCM that I just replaced did not output to the MIL light, or output VSS or tach signals. It's obviously not running now, but the fact that I know can toggle a MIL leads me to believe that there were additional gremlins in the previous PCM, and now at least the hardware side is ok, but it threw me off have the MIL light stay on solidly..

  7. #7
    Tuner in Training
    Join Date
    Dec 2011
    Posts
    16
    Is there any type of logic diagram or flow chart that I could backtrace why the computer is commanding such a low cranking AFR, aka see what parameters/multipliers are going into that calculation??

  8. #8
    Advanced Tuner
    Join Date
    Jun 2012
    Posts
    225
    The ses light will stay on until you start car.

  9. #9
    Advanced Tuner blownbluez06's Avatar
    Join Date
    Jan 2008
    Location
    Forney, TX
    Posts
    982
    where did you get your injector offset vs volts AC info from? Looks quite strange. Your cranking VE looks like nothing I recall seeing.
    You need to go get a stock file for this PCM, copy them back to stock and change only what you need to change. Many strange values in there that I don't trust. Change the enable torque too. 0% could cause you some problems.
    Use the compare function to list every deviation from stock and eliminate any deviation you have that is not justified. For now, put the stock injector offset vs volts AC back in too.
    Hsquared racing engines RHS 427, Procharger F2, Moran Billet Atomizer injectors, Alky Control,Mast LS7 heads, Nitrous outlet kit,Tilton quad disc clutch, DSS shaft, RKT56 ZR1 trans, RPM Quaife diff. Built and tuned by yours truly.