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Thread: LNF idle issue?

  1. #1
    Tuner in Training
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    Oct 2015
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    LNF idle issue?

    hey guys, my car started to have idle issues after i installed my 3 bar map sensors, and made my tune adjustments. you will notice the issue in the log. once the car is warmed up the idle goes back to normalbut will stumble every so often while sitting at an idle. im just learning to tune so im not exactly sure where to start looking. this was originally a zzp tune that a modified. so here is a log of the bad idle and also my tune file. if someone could point me in the right direction and tell me where my issue lies i would greatly appreciate it! Bad startup.hpl
    mahon new tune.hpt

  2. #2
    Advanced Tuner
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    Mar 2009
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    There are so many things it could be. First, you need to log your cams, there is a thread by GMTech where he posts a great config file, and another thread by him that shows how to integrate that properly on your computer.

    Second, your timing is erratic, lending to the rough idle. Hand smooth all of your timing tables, make all 4 of the intake tables the same values, all 4 of the exhaust tables the same value. Then work on your optimum spark to smooth the idle the rest of the way.

    All of the information is out there on how to do this stuff, so hopefully that helps you out. Post up if you need more help.

  3. #3
    Tuner in Training
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    I understand this, I have read all of those threads. I also knew it was a timing issues compared to my stock log. But I never manipulated the timing tables prior to the log, that's why I wasn't sure why I would have a timing issues.

  4. #4
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    So to get us on the same page. You installed the two 3 Bar MAP Sensors and changed your tune for the MAP sensors, then you started having your idle issue immediately? Or have the sensors and tune been on for a while and then started having a idle issue randomly?

  5. #5
    Tuner in Training
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    I do not believe the map sensor is the problem, as I stated before I did other tune adjustments at the same time. I believe it was due to turning of the catalyst over temp.

  6. #6
    Advanced Tuner
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    Okay, just wanted to know if problem occurred immediately after change or if the vehicle had been changed for a while and randomly started having issues.

    Do you have a cat on the vehicle still? And do you have rear O2 sensor still?

    And when you say turning off catalyst over temp. You disabled catalyst heating? Or adjusted CAT overtemp protection lambda? Or did you adjust camshaft angles while catalyst heating is in progress?

  7. #7
    Tuner in Training
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    I have done no timing adjustments and I disabled catalyst heating and over temp. No I removed the car and yes I still have the rear o2. All the changes to the tune to remove the cat were done by zzp. I picked up tuning it after that modification.

  8. #8
    Advanced Tuner
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    Even though catalyst heating is disabled. Copy and paste your main camshaft base angle table to your catalyst heating tables. And see if it makes a difference. You can also set your base angle factor tables to 1 across the whole board.

  9. #9
    Advanced Tuner
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    Mar 2009
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    Even though you did not make any timing changes, other changes will affect how the car reacts, which will affect how the timing is commanded by the ECU, this is the beauty (and the very frustrating thing) about torque based ECUs. The Optimum Spark (OS) table will help you smooth that out.

    If all else fails, put in the old tune with only the MAP sensor data changed and see if that helps at all, then you can at least narrow the issue down to some other change you may have made. Also, check to see if there are any leaks in any of your tubing/couplers. We always recommend making one change at a time for this very reason, then you know if something changes for the worst exactly what you changed.

    Keep us updated.