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Thread: Unable to find steady idle

  1. #1
    Tuner in Training
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    Unable to find steady idle

    2005 Magnum RT, heavily modified, engine rebuilt .020 over, boost cam, ported heads and intake manifold, torqstorm supercharger, smaller pulley, and 6spd manual conversion with a lightened flywheel (the dodge challenger dual mass is too expensive and wouldn't work with the ACT clutch) for the big changes.
    I've used this vehicle very much as a test bed and learning tool for tuning and tried to notate as many of my changes as possible. Recently switched to a smaller pulley for 2 more psi and a bigger 90mm throttle body and ported the manifold to match (at that time I found out the previous arrington 85mm unit had a reducer stuck on the back of it which negatively affected a lot of math). Since moving to manual it has always had throttle issues, and I discovered a lot of it was due to the misconception on the size of the TB. Went back in and fixed a lot of the throttle body modeling following guides on here and now the overall powerband and throttle response is drastically improved, however just at random sitting clutch in or in N, my idle RPMs will shoot up and begin cycling, sometimes even stalling out. Other than that, the car is a joy to drive. The only oddball bit of tune is that the car thinks it is always in Neutral (this was an early PCM that couldn't be modified to accept a manual tune) so I don't know if that as effects on how the car digests information but it doesn't seem to have much if any. Have attached tune and log. This time, once it started cycling, it eventually couldn't save itself from the stall. This makes it an enormous pain in the *** in traffic. Any help or direction where to go would be incredibly appreciated as I've been chasing throttle issues ever since the manual conversion and I'm unsure if I need to keep going down the TB airflow rabbit hole, the Idle Torque spark tables, or the spark minimum (because it does seem like the timing goes low before it tries to catch itself), if I can make it smooth to take off in, I might finally finish fiddling with this tune (probably not).

    newpulleytunecomp1norumbletimingtunePEup90mmCurvechangeXminsparkidleRPM.hpt
    idlestall.hpl
    Last edited by TerrysTrans; 3 Weeks Ago at 01:43 PM.

  2. #2
    Senior Tuner
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    are you logging the wrong 02 sensor channels?

    try adding the sae ones

    what you have are all over the place

    no way that is actual data

  3. #3
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    Yea I think I got a junk one. I just replaced 2/2 after it got ripped out. New one on the way. I made some more tweaks to timing and the throttle tables and it's no longer doing big race ups but the idle still wants to oscillate about 100 rpms. Will see if I can get more logging done. Been raining for 4 days..

  4. #4
    Senior Tuner edcmat-l1's Avatar
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    Do you have your stock, unmodified tune file for comparison?

    EFI specialist
    Advanced diagnostics, tuning, emissions
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  5. #5
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    i have A stock magnum for comparison lol - my tune has been tweaked over years and many modifications along the way.
    stockmagnum.hpt

    After another couple logs, I've added a little more timing to the minimum table, continued to tweak and dial in the TB airflow and VE tables, and took a few more suggestions from the big How-To write up sticky. Will load the changes and take another drive and log.
    Last edited by TerrysTrans; 3 Weeks Ago at 02:44 PM.

  6. #6
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    Couple of updates to the tune and another idle log, this one right around 1 minute 20 with no input it just starts cycling and won't stop after sitting idling totally fine. Most of my steps I've logged in the tune notes.

    newpulleytunecomp1norumbletimingtunePEup90mmCurvechangeXminsparkidleRPM.hpt

    idlefluc.hpl

    Really stumped and frustrated at this point.

  7. #7
    Tuner in Training
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    Bump

    For reference I tried following this guide:
    https://forum.hptuners.com/showthrea...ntrolled-Setup

    but I could not get the logs to pull correctly.