confused about a TCC paramater

[greggbruceauto]

1227165 ecm, $6e mask, 89 firebird TPI
there are 4 tables in this bin
TCC unlock speed vs. %TPS (not in 4th)
TCC lock speed vs. % TPS (not in 4th)
TCC unlock speed vs. % TPS (in 4th)
TCC lock speed vs. %TPS (in 4th)

do these mean they either 1) lock or 2) unlock -- if it ABOVE this TPS, or BELOW this TPS?

I understand the 4th and not 4th, but the other part is confusing.

so the lock paramater (not 4th) is set at 89.84 %TPS @ 52 MPH. does that mean it WON'T lock UNTIL 52 if the TPS is UNDER 89.84 % ? or it WILL lock at 52 if the throttle is less than 89.84% ?

the unlock parameter (not in 4th) is set at 30.08 %TPS @ 52 MPH -- does that mean it unlocks BELOW 52 if the throttle is less than 30.08% ? or does that mean it unlocks ABOVE 52 if the throttle is more than 30.08%?

some of those can't be right -- I am confused as to what is what.

and if I don't want the tcc to work below 50mph at all, which one do I set to what?

[RobertISaar]

yeah, the early TCC stuff was quite confusing...

Rbob did a paper on it a long time ago, but essentially the ECM by default wants the TCC locked and looks for reasons to unlock it. if no "reasons" are found, it locks.



here's an example from a similar situation(A1 with the early trans code, though for the F31 transmission option, there is a second set of tables that have MPH as the changeable value, rather than TPS).

on the left half is 3rd gear, right half is 4th gear. they are "paired" in that one is an upper threshold and the other is a lower. they're not so much lock vs unlock as they are "unlock above this vs lock when back under this".

note left two tables, at 40MPH, 27.84% and below will allow lock while 35.39% and above will unlock. the tables are intended to have a hysteresis built in, so assume you're crusing in 3rd at 40MPH and you raise throttle above 35%, TCC unlocks, let's also assume you don't accelerate(really big hill, adding just enough throttle to maintain 40MPH), when TPS drops below 28%, TCC will be allowed again. make sense?

now let's look at 4th(since it's relevent to one of your questions): first couple of entries in the upper table are 0. looking at the logic i just explained, since throttle will absolutely be 0 or higher %, when at 40MPH or below, TCC is disabled in 4th and the lower table won't matter.



make sense? later code utilized a different method of on/off, one that makes a lot more sense.

[greggbruceauto]

BLESS YOU !!! that was the explanation I was looking for..... !!!!

[Six_Shooter]

Interesting. Thanks for the post Robert.