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Thread: Big cam LS7 idle issues, looking for a bit of assistance.

  1. #1
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    Default Big cam LS7 idle issues, looking for a bit of assistance.

    Hey I just recently completed a rebuild of my motor due to low oil pressure, at the same time ended up putting in a texas speed stage 4.2 cam (Cam Specs: 248/260, .657"/.655", 111 LSA, 108 ICL) and put on a set of their PRC 265cc heads. I have an MSD airforce intake, NW 102mm throttle body, Haltech CF112 intake, ARH longtube headers 1 7/8" with no cats.

    After all of the mods I uploaded a starting tune after slightly modifying the stock tune, putting it into speed density and bumping up fueling just to start things off. The car would fire up and immediately die afterwards unless I use the pedal to keep it idling. After messing around with the speed density minimum idle airflow settings and other various airflow tables the car would still not idle on its own. Tried adjusting the ETC area from 7200 down to 5500 and worked around from there to trick the ecu into thinking it had a smaller throttle blade and allow more air in. After reconnecting the maf and running in closed loop the car will idle erratically for a moment and then idle on its own. So currently in the maf enabled tune it will idle without assistance but still stumbles every now and again, seems to run pretty lean as well mainly around 15-16 just idles but does dip down to 14.5 occasionally.

    Trying to increase the mV signal for the O2s to allow them to pull the car to a richer value, tried 525 first and it seemed to help so now going to try 550 and see how that affects it.

    Haven't really driven the car other than two minutes to get gas, just been idling it in the driveway. When I did take it out the car wanted to surge big time and when shifting the rpms drop leading to almost stalling.

    If someone has a moment to glance over this tune and see what could possibly be done to help with a big cam, only ever tuned the BTR stage 3 cam before and didn't have any of these issues with that cam but this one seems like an entirely different ball game. Can't even close the vacuum operated exhaust valves.

    Here is also a video of it idling if you would like to hear, this was before putting it back to MAF when it needed to be assisted with the pedal to maintain idle
    https://youtu.be/col5DxUlims
    Attached Files Attached Files

  2. #2
    Joe (Moderator) joecar's Avatar
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    Try bumping up the low end of the low MAF table.

    Spark seems to be jumping, this is because the various spark tables that it is using near idle are too different.

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