ZF8HP70 fails 1>2 shift under WOT

[james1595]

So just keep increasing the tourque reduction till it shifts? Ive tried, but with not much luck. Do i need to increase forced torque intervention as well?

[LilSick]

increasing forced will make the rpm graph no longer have a peak

makes it nose over

[james1595]

increasing forced will make the rpm graph no longer have a peak

makes it nose over

so should i decrease forced torque and increase main torque intervention? what about gear engagement torque intervention? it seems like 1st gear is the worse for shifting, whether it be at part throttle with long shift, or wot with no shift. but 3rd through 6th are good and firm. 7th and 2nd are a little sloppy but nothing terrible and eight is kinda in the middle. not bad, but nothing great. id really like some help and get this fixed. ive tried every i can think of and nothing really works. 1 thing may help, but then makes 10 other things worse.

[LilSick]

so should i decrease forced torque and increase main torque intervention?

what about gear engagement torque intervention?

dunno... i do not have your current tune

gear engagement tq interv is odd huh? stock trans tune has all zeros for low gear (and R) like they are relying on table 36000 garage shift tq reduction for that one, but has values for all other gears. i leave it stock

[LilSick]

went last night

spark and fuel only

https://youtube.com/shorts/ZA_ghsXCY...mQdGadlabF08d2

[LilSick]

i made it to the semi's sunday

there were 4 mopars in the 16 car sportsman field (7.30 to ?)

two 1320's, a old dart and my junk

the other 3 all lost first round

my rag was deadly consistent

i was 030 on the tree and early numbers all said dead on (lifted) going in to the semi finals

my opponent had a 150 light in that one, and i still lost, even tho i ran dead on with a 1 lol

you know what that means

anyways, the point is that the car is shifting right where i want it to and it is doing so consistently

hope yours is too

hmu if not

[james1595]

Im making progress. Havent been wot, just tuning part throttle. But it shifts much better in 1st now, still some work to do, but a step in the right direction

[james1595]

Went to the drag strip and have some positive results. 1st gear, although comanded to shift at 6k, shifted at 6400. Not perfect, but a step in the right direction. Nicked the limiter a few times 8n the other gears, but thats on me for setting it so close to the shift point. All in all, progress. I know theres more in her. Ran a 12.6 at 113. With a 1.93 60'.

[LilSick]

lets see a log!

[james1595]

here is the log from the track.
3-10-2024.hpl

[LilSick]

your 'not shifting' problem is still present

it moved from top of low gear to top of 3rd

strange

now that it is on the track and hooked dead up you can figure it out and fine tune tho

try to address the top of 2nd (the way it noses over) with the ramps, the offset and the slip time

gotta figure out why it slipped going into 4th too

[james1595]

After looking over the log more, i saw that the problem wasnt improved. Im just going to cut all the losses and buy a new transmission. This has been an issue for almost 4 years now and it is no longer an issue of tune. Its just a bad transmission

[LilSick]

cool

curious if you put the same tune in the new trans, go back to the track and make a pass, if the log is gonna look the same or not

let us know

[LilSick]

also curious if yer car has a tazar in it????

and what values (special functions) for gear and tire diameter do you have in your bcm???????

[james1595]

I do have a tazer installed. And nothing has been changed for gear or tire, was told thats not important

[LilSick]

oh

then i am 99% sure i can fix your problem : )

do not yank trans

do not send it and $5k back east

++++++++++++++++++++

i need 5 things:

what does tazer see for tire diameter?
what does scanner see for gear ratio?
what does scanner see for tire diameter?
what is the actual (measured) rollout of your rear tire?
what gear is in the car?

there is no magnetic pu and rotor in the trans reading output shaft rpm

its a calculation

the bcm, tcm, and pcm all work together to spit out a number

*if you make diameter 15" the car will be in high gear before it is going 20mph

**it will run into the limiter if it is off the other direction : )

[james1595]

I was told you dont have to adjust any of that. Also, it had the issue with the factory rear gear and tire, so im not sure if thats the issue. I can try, but not sure if it will fix it

[james1595]

update. same transmission. i adjusted a few parameters and lowered the shift point for 1st to 5800 rpm (did 4700 at first but raised it up for this log). it seems to be shifting much better now at wot and part throttle. its not perfect, but its much better than it was. here is a log from today.
3-23-2024.hpl

[LilSick]

why you so hard headed?

[james1595]

Im not sure im underatanding what you are trying to say.