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Thread: New to LS1 Tuning

  1. #1
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    New to LS1 Tuning

    Hey guys, I have just setup HP Tuners to my project LS1 swapped e36 bmw chassis. Saved a file of the current tune today. It has a 'startup idle tune' (Vats removed, Post cat o2's removed, STFT/LTFT disabled). The idle is setup perfectly 875rpm at operating temp, stays around stoich. Has a terrible time recovering from any throttle input upon letting off the gas. According to my wideband gauge, seems to be rich most of the time when on the throttle then badly lean upon letting off to the point where it dies. New to tuning looking to get some help/advice as to where to go from here?

    Drivetrain: 2002 Camaro LS1 & T-56

    241 cylinder heads
    228/230 112LSA camshaft
    LS2 intake manifold w/92mm cable throttlebody
    Sikky swap headers (1-3/4" primaries w/ 3" collectors)
    Stock LS1 injectors
    5 wire truck style MAF

    I have attached a file of the current tune if anyone would like to take a look. Any help would be much appreciated. Thanks.
    Attached Files Attached Files

  2. #2
    Tuning Addict 5FDP's Avatar
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    Change the open loop EQ ratio to 1.00 (stoich) above 140 degrees. You can't have the open loop fueling moving around on you, since closed loop is disabled it will use the open loop table to determine what commanded fueling to follow.

    Setup the car to run off the MAF or the VE first. Use your wideband with a wideband error to fix one half the airflow model first. Get one side done and then work on the other. Most issues tend to go away when the fueling is correct.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    Awesome thank you I will definitely correct the open loop ratio asap. I was thinking my next step would be setting up for VE as a starting point/learning experience then move on to MAF later on.

  4. #4
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    I changed the open loop EQ like you said & increased fuel across the whole VE table by 8% then been dialing it back in all areas necessary getting the afr's closer to stoich from rich. Helped a lot, just need to keep fine tuning it. Thinking about making my idle slighly rich, sitting around stoich at the moment. Would that be a good idea for this camshaft?

  5. #5
    Larger cams don’t tend to respond well to more fuel. It’s fairly common to have leaner readings at idle, especially if you have a lot of overlap. Since you have headers too, the delay to the O2’s is increased as well, further complicating closed loop idle conditions. And with over lap, there will be some extra air in there too further throwing the readings off. At higher flow it’s a non issue. At idle where cams give you problems, it can get much trickier.

    What is the issue? Why do you want to increase fuel?

  6. #6
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    I tried leaning it out a bit before but has trouble staying running although maybe it was not enough. Interesting I didn't know the overlap had that effect on O2 readings, I'll try
    to find the sweet spot this time. Usual issue is it has trouble keeping running upon startup without some throttle at first & then it's fine, mind you this is with it idling
    at around 12.6-13.6:1 afr.