Details:
5.0 Ford running MSII on stock engine (late model roller engine)
4R70W stock trans and converter controlled by Microsquirt using Ford sensors / hardware with custom wiring harness
Trans shift very smooth and clean through each gear. Very conservative tune shifting at 2k or so gets to 4th pretty quick. Converter locks in 3rd and 4th. When decelerating to a stop the downshifts are smooth except 2-1. On this shift I get solid clunk that is abrupt and startling. It has been doing it for a year / 4k miles so I do not think it is harmful. I added a relay to ground a wire on the microsquirt when the brakes are applied this was identified in the software as a way to tell the micro that to unlock the converter.
Tune is attached maybe someone can see an errant setting. I'll try to save a log tonight on my drive home.
4R70W trans clunk on downshift
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Re: 4R70W trans clunk on downshift
Maybe a little less line pressure at low load downshifts?
Matt Cramer -1966 Dodge Dart slant six running on MS3X