john3daly

iTrader: (4)

I took the car today to have it dyno tuned after ther LS6 intake and 237/242 603/609 install. Well, all is going well, I pay and all and me and a couple friends get in the car to drive home. Guy tells us to beat on it a bit to see how it does. So I pull out and go WOT, car goes to 4000'ish and shifts....then just bogs and stays around 4k. 15 different tunes later, it does the same thing.....finally, we put it back to stock tranny tune, I use my HPPIII and set it the way it was before I brought it in, still, the same thing, but only 95% of the time. Occasionally it ran like it was supposed to, which is like a monster. They have no idea wtf is going on, neither do I.

Also, while there, the car started and idle'd perfect. No helping with the throttle or anything. Once I get it home, it won't start w/o cutting off, unless I stay on the throttle and work it until it idle's. If I shift it manually, it'll run the RPM's up like they're supposed to be, but if I just leave it in OD, it won't downshift but on rare occasions. Hell, usually it just stays and pulls in OD....why will it not downshift? Why will it work occasionally, and be stupid later?

WTH is going on? Help! Someone!

jimmyblue

iTrader: (11)

I fought with a very similar problem back
when I was trying to be clever with the
torque management on my car (trying to
make a flat torque-limit profile). I would
occasionally get into this "hang" state that
I had to release throttle, to get out of. I
never was able to eliminate it until I went
back to the trans TM table and restored
the stock values, & scaled. Though just
zeroing it should work, if you like beating
on your trans.

I thought it might be abuse modes, killed
them with no effect. Only the TM seemed to
be involved in the end.

My suspicion is that there is a nasty interplay
between the trans torque model (Delivered
Torque - Trans) and the torque management
and/or abuse stuff (maybe hidden), that comes
about from the very different torque vs slip RPM
profile on an aftermarket converter. The PCM
just doesn't know that you put on a piece where
2000RPM of slip at 4000RPM engine is normal;
it refers to the built-in "mental model" of the
stock converter and figures you must be making
-huge- torque multiplication and wants to back
you way off.

There is a "Max KR vs RPM" field in HPTuners
that your tuner may have an equivalent for,
raise this from -10 (stupid) to something like
+10 degrees and see if you move from hang
to a slightly-detuned acceleration. That's
where I've come around to, TM-wise; let it
think it's in charge, but shorten its leash.

HPP3 won't touch some of the things that your
tuner might have done. Lot of stuff it just will
leave the way it found it.

However, new heads, big cam, not to say it
couldn't just have a hell of a mystery rattle at
4000RPM and set off the knock sensors and
pull out a whole mess of timing. That wants
logging. So does the TM stuff, just different
aspects.

Now, the idle and shifting stuff I have no idea.
Sounds like there's something fundamentally
messed up, maybe TPS (shifting is TPS & MPH
idle is TPS involved too) or something. I'd expect
that cam to really whack out your idle and have
a tough time learning, see cold start be really fat
and hot start might be confused too; really low
cranking VE and low idle VE relative to stock
tables. Watch your commanded fuel air multiplier
when you're having idle-death problems, your
MAP and the IAC action. Raise the idle airflow
to help backstop the RPM-control loop which can
fall through the floor if things respond too slowly.
Lower the open loop fuel air multiplier vs MAP vs
ECT table in the areas that cover cold idle. Look
at the VE table vs stock, see whether that has
been massaged for you or neglected. Set the idle
airflow floor to maybe 80% if the actual running
idle airflow you log when it's doing good.

For the 4000RPM hang, log the knock retard, the
actual spark advance, the delivered torque-trans
and see whether you are being hit by knock or
by TM-at-shift. Go through the tables and see
if there're any spikes or holes that you might get
"stuck" on/in as you slide across the map, maybe
just a fat-finger "oopsie" in some spark retard or
fuel table. Try and narrow down the "suck space"
and you'll narrow down the list of suspects.

john3daly

iTrader: (4)

Thanks man! I'm going to have them check out this thread, hopefully it solves everything.