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Thread: Truck wont start! Cold crank, was tuning VE after heads/cam

  1. #1
    Tuner in Training
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    Truck wont start! Cold crank, was tuning VE after heads/cam

    Background: Silverado SS, 799 heads with light port work, 226/229 573/582 112lsa, br7ef plugs gapped at .035.

    So i finished the install got the truck running and started tuning. I followed the idle tuning for cam here: http://www.silveradoss.com/forums/to...sing-hptuners/

    Since i didn't have it all done to go till 2am i left LTFT on so i could have a safer drive to work. Shut them off on the way home to log. MAP was unplugged so i didn't have any usable histograms. From there got a few logs, and used the AFR error % to start dialing in VE.


    Then i let it cool down and went back out 3 hours later and its about 26* out. It cranks and started then stalled when i put it in reverse. Now nothing!!!!


    Attached is the last running tune. I do not have any logs. Also attached are some mods i made to try and get it starting. Never had to tune for cold weather, the only other GM tuning i've done was on a roadster so it only saw warm weather.


    I tried adjusting Cranking VE up then down unsure of which to do, then did some quick reading and saw that cold weather causes engines to run rich since the air is more condensed. So i reduced VE. From there i increased Cranking Timing 3*. Then lastly i increased Start up Airflow by .265 to .794 below 68*

    One thought is the BR7EF plugs are not good for this cold. When i started the truck last night it had been sitting in the garage with a heater infront, then this morning we had some warmer weather and it was above freezing.

    Silverado SS Idle and VE tuning 3215_Last running.hptSilverado SS Idle and VE tuning 3215_Cold start mods.hpt

  2. #2
    Tuner
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    Make note of your DTCs and then clear them. Might start right up.
    2001 Z06 : 856/830 : Built LQ9 403ci : D1SC 17psi : Self-built , self-tuned.

  3. #3
    Tuner in Training
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    Gave it a try this morning now that its 10* warmer out. Fired up and died shortly after. I took a log, its attached. I think i ended up flooding it last night because after i tried a few changed today it wouldn't fire again.

    Do i need to increase my idle
    Idle Start up airflow.png

    I added .05 to 32* and below, but haven't tried it yet.

    Any other suggestions on what to do??? This is currently my daily driver since a pothole destroyed the wheel bearing on my VW.







    30 Temp Start log Died.hpl

  4. #4
    Tuner
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    Looks like your issue is too much fuel. Wideband is in the 10's. Your commanded AFR is in the 7's. That's not right.

    Put your idle airflow back to stock and multiply it by 15%. In fact , I would go completely back to the stock tune and try it. Then make as few/minor changes as possible from there.
    2001 Z06 : 856/830 : Built LQ9 403ci : D1SC 17psi : Self-built , self-tuned.

  5. #5
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    So i did get it started. Took a few tries thought. I had to pull the fuel pump relay and crank it over to burn off the extra fuel from flooding it a few times. Anyways attached is the tune that finally allowed it to start. Once it was warmed up it wasn't running as great as the latest running tune i had. So i swapped over to that one, and kept tuning VE while it was warmed up.

    Its been sitting outside cooling off for a few hours, so now i'm going through the tune that started it and make some of the same changes to the tune that runs nicer. Out of desperation and experimenting i changed more than i needed to get it started.

  6. #6
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    She starts up fairly well now, its about 30* out but after a few hours of the truck sitting the ECT was still around 50* or so.

    My issue now is i think my innovative LC2 crapped out. Its been in there for a day or so. Im going to check my ground and see if that helps. Possibly run it and the 12v power strait to the battery. I also need to find my serial to USB and swap the other analog output to wideband so i can install my gauge and make sure its safe while i run logs with just the MPVI.

    Here is the latest tune, i manual went through and smoothed out the VE. Going to flash it in the morning with the smoother VE and run a full cold start + 30 min drive to work.

    Silverado SS 3315 cold weather crank Best starting smoothed ve.hpt

    Any advice on what may look off and to look into??

  7. #7
    Tuner in Training
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    Here are my logs from this morning. LC2 WB still not reading. It started fairly well this morning, but sounded rough as it warmed up. I definitely need more work in tuning the idle. I think rpm needs to come up and in park/ gear timing needs work.

    Over all LTFT is under +/-3%. I am getting some KR on the few WOT pulls i made, so i'll go back and dial the timing back in those areas.
    Attached Files Attached Files

  8. #8
    Advanced Tuner
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    Your idle>airflow> base running airflow is way high I am surprised it even runs. You need to get that into range first. Go back to stock and add like Knautz said. Just for a comparison my RAF at operating temp is 4.81 g/sec and you have yours at 64.00. Just a FYI everyone here uses metric (g/sec for idle airflow) so you might want to change your units to g/sec. Once your car will idle run the Russ K idle config from a cold start to operating temp so you get your RAF table correct. If you are an auto you will need to do this in park than from a cold start in drive WITH PARKING BRAKE SET.

    http://www.hptuners.com/forum/showth...ht=idle+tuning
    Last edited by gagliano7; 03-05-2015 at 08:17 AM.