parish8

iTrader: (6)

i took the truck to the track last night, at lower boost levels everything was working well. 12psi or so was fine, i was lowering the tire pressures and turning up the boost trying it get it to move off the line better, adjusting the fueling up top. things were going ok.

as i turned it up my shift points started to creep up. the first couple of times it was creeping up it seemed like i was able to get it back down just by comanding it sooner but as the boost got closer to 20psi i completly lost control of my shifts.

i have my 1-2 shift set at 5200 and i actualy hit the rev limiter at 6800. it seems to be directily related to power. it shifts nice and firm when it does shift. the tranny oil looks and smells good and the level is right on.

this problem seem to apply to the 2-3 shift too.

the line presures are vacume modulated now, i dont rememeber if i adjusted any of the other tranny functions other than the shift points and lock up stuff.

SmokingWS6

iTrader: (1)

The problem seems similar to problems i've experienced with 98 Fbodies. The bigger the converter/more power you make the lower shifts points will have to be set to avoid hittint the limiter.

From the best I can tell the pcm is commanded to shift based off the input shaft rpm, not the motors on 98's. Just the other day I was tuning a car that required setting the 1-2 shift pt at 5300 to avoid hitting the limiter.

I'd keep bumping the rpm down untill it stops. Unless your making so much power that the converter cant handle it and its slipping approx 1500rpm.

cablebandit

iTrader: (37)

also....try it with the vacuum hose unplugged...you will have full line pressure just to try and make sure it isnt slipping. could you be blowing right thru the converter?

lisa33

Have had the same problems widh my old 4l60e and now widh the 4l80e... try to lower the shiftpoints 1000rpm or more so you get it to shift, after that raise the shiftpoint so you get them where you want..

parish8

iTrader: (6)

i think you two are right. how do the shift times effect things? is there any point in messing with those numbers?

cablebandit

iTrader: (37)

i dunno how the shift times affect things at WOT. If I lower mine from stock .500 to .200, i can feel that the shifts are quicker at say 30% throttle. At wot I dunno what it does. Now I have read that setting the shift times to .000 disables "shift adaptive learning"...what the hell that is, i dunno. i'd try setting them to stock, if that dont work, lower them some...if that dont, work set them to zero

SmokingWS6

iTrader: (1)

I bet trans pressure is maxed out at wot, if not it may not hurt to lower you shift time tables to say .150 to .250 for times for 1st and 2nd gear. However it should make no difference since its vacume modulated. Shift adaptation is a pressure modifier.

strokedls1

iTrader: (1)

Could be overstalling the converter with too much power, or the clutches just can't take that much power. The 4L60e did the same crap on mine when I was 600rwhp. The 80e shifts so tight it is rediculous at the same power level. I set the shift times at .350 seconds for a little quicker shifts.

TheRealSS

same thing happens to me and i just got my 4L80e. i still haven't hooked it back up to my labtop to change some settings. i'll do that later