I am new to ZF Tuning and I?m having a problem deciphering the files. All I?m wanting to do is lower the 2-1 coastdown shift speed or soften it up in an attempt to correct a clunk. Dealer says it?s a normal characteristic in a 15 Grand Cherokee 3.6L. Myself nor the customer like it. Any help would be much appreciated.
2nd to 1st downshift is "always" an issue...Originally Posted by Truefordguy
The way to fix it is:
- Reset adaptation (to see if it helps... drive for a while... I mean, a couple of days). If the issue persists, the solution would be a combination of torque converter opening point, shift RPM, pressure and timing.
Hard to say the exact value. However, fully possible to get it fixed!
DO you have a flare 3rd - 4th upshift under light throttle? THis is also a common issue for this model...
Thanks.
DodgeBoy.
YouTube: https://www.youtube.com/@dodgeboy2785
Thanks for the response!
No flare or any issues on upshifts. Vehicle came in with a SEVERE 2-1 downshift issue. Fluid and pan was full of aluminum. "A" clutches were completely wiped out. Overhauled rebuilt T/C from Precision. w/ new clutches and pistons in every cylinder except "D" clutch. That cylinder air tested good and clutches were fine so only replaced clutches there. Installed low mileage known good VB w/OE TCM. Initial test drive after resetting adapts at operating temp of about 170, the harsh downshift on 2-1 was still there. Had dealer reflash with latest Cal. That did help the down shift a lot but did not eliminate it. I am studying the tune file trying to make sense of their terminology and am hoping someone can enlighten me.
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