Lock Up Won't Engage!! Gurus Please!!
 

Gurus I need some assistance. '05 GTO with a 2800 Art Carr. Lock up will engage periodically and my best luck is when the vehicle is cold and I immediately get on the road. By periodically I mean once every 100 miles. The funny thing is that after I have it reflashed for whatever reason it starts to work consistently, but gradually stops. Anyone have experience or thoughts on this. Oh and this also happened with my C5 I had, exactly. Both converters were Art Carr.

Two semi-probable things - misfires (all or nothing, unlock
at random intervals or lock randomly) and TCC duty. TCC
duty has behind it a poor main pressure level commanded
too.

Small converter bodies mean less flywheel and more crank
jerk which is -seen- as misfire whether or not actually
missing. Test this by filling your misfire tables with 32767
values and if it gets all better, try something more subtle
like bumping the misfire thresholds until it quits but just.
Then you still have misfire warning for real problems.

Small converters have smaller clutches (as a rule; mine
was built for beefy) and need more TCC line pressure.
Stock tune has TCC slip learning (seeks to barely slip
and fades pressure to get there, then you add a little
load and slip like mad), a soft-apply PWM scheme (for
that highly desirable chatter effect) and a line pressure
profile in the main force motor that commands 0% (min
line, not truly 0 but way short) from which the TCC PWM
valve can only reduce from there. This makes for slip up
grades etc. at cruise even with 100% TCC PWM duty.

Set your TCC PWM min duty to 98% and see if this is
sufficient. If not look at General Pressure (HPTuners) to
up the TCC-locked line adder. There may be similar knobs
in other tuning softwares, I don't know. If not you can
bump down the lower end of the force motor current
table to get more line, but this adds to pump losses etc.
and low-throttle shift harshness which you'd then have
to rework the shift pressure tables for (or not).

If this is a car with the TCM (tranny control module) as
a separate piece, then it may well be different from
what we see on the GenIII (PCM only) setups. Not sure
whether that was '05 or '06, where it cut over?

Good info jimmyblue. I believe the problem is misfire detection falsing because of the cam. Check the misfire count setting in the PCM programming; if it is still at the stock values then raise the numbers a bit and see if that helps.

John