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Thread: Jeep tuning master thread

  1. #1
    Potential Tuner
    Join Date
    Jan 2023

    Lightbulb Jeep tuning master thread

    Hello I am Tom an experienced Tuner and Jeep enthusiest !

    I have been messing with my HP TUNER MVPI 2 PRO and want to start a thread on how to tune 4.0 engines.

    My finding =
    - We can now adjust transmission protocols by adjust the shifting triggers from the PCM so that overdrive downshifts to 3 sooner for those hills and highway driving (previously you needed almost WOT)
    - We can adjust the torque converter lockup parameters and make life more enjoyable on the highway
    - My stock tune was pretty messy im sure yours was too, the best thing to do is smooth the ignition curve out and ad more from idle to WOT through 3500 RPM's = still testing
    - I am a big fan of DFCO and now my XJ coasts better down the HWY and gets better gas mileage, When it triggers my motor is silent its kinda cool
    - when changing any table be aware ignition and fuel timing have multipliers and we cant just change the EGR off base map

    My tuning experience comes mainly from Carburators and to tune my jeep I started that way and turned my PCM into an emulator to act like a carburator which gave me a great basemap to tune in for my Large upgraded camshaft, low vacuum added so much fuel so it needed to lean out considerably, next i datalogged with wideband and adjusted from there then smoothed out the 3D map with my mouse, datalog - repeat I have much more work to do

    0 to 2000 rpm 14.7 to 1 2 to 4000 rpm 13.5 to 1 4000 to 5400 11.5 to 1 and set shift point to 5400 rpm. - soon to be 14.7 to1 then 13.5 to 1 then 13 to 1 i am dialing it in slowly as im playing with timing at 34 degrees max now - tune timing fatt then lean out and watch plugs and pinging sounds. (wish i had a standalone knock sensor $$$ to tell me when to stop adding timing )

    after my tune is done at 25 degree F Ill wait for summer time then datalog and adjust intake air multiplier to match - no other way to test only guess.

  2. #2
    Thanks Tom, Thanks for starting this thread. Going to be tuning our 4.0/4.6 stroker this spring once the build is done. It's also 25 degrees here in Rochester, up from 14 this morning. Where are you working from that it's 25 out? - RZ