1993 F150 4x4 - Trans Tooning

[efloth]

I hope this is good. First time I've burned out lol. has cold start at 36 degrees. Had to crank it 3 times.

IIRC the tprel/epc functions can be ignored in certain circumstances. Sometimes it shifts beautifully and others it is slamming into 3rd and 4th still. I wonder if we could force it to use the tprel/epc funtions all the time.

[efloth]

I'll work on locating these:

TVPMIN = Global minimum TV_PRES clip, psi.
- TVPMN1 = Minimum EPC clip, PDL = 1, GEAR = 1, psi.
- TVPMN2 = Minimum EPC clip, PDL = 1, GEAR = 2, psi.
- TVPMN3 = Minimum EPC clip, PDL = 1, GEAR = 3, psi.
- TVPMX1 = Maximum EPC clip, PDL = 1, GEAR = 1, psi.
- TVPMX2 = Maximum EPC clip, PDL = 1, GEAR = 2, psi.
- TVPMX3 = Maximum EPC clip, PDL = 1, GEAR = 3, psi.
- VSSTAL = Maximum vehicle speed to do stall EPC.

We are obviously running into some minimum clip. I tried going further negative on EPC for 3rd and 4th but it made no difference. Since the latest update, it is shifting hard in third and fourth all the time

[efloth]

FN620(TV_PRES) - EPC VFS transfer function is at 0xb99a but not sure if it is a good idea to modify.

fn622 and 622a do not appear to be implemented in A1c AFAIK

[efloth]

It looks like setting negative values for EPC was actually raising pressure. I set them back to 0 and things softened up quite a bit. I shifted Fn620 down a few cells and it softened up 1st and 2nd but did not affect 3rd or 4th. I'm guessing that 0 EPC means 0 current to the solenoid so fn620 would have no effect at that point. Is negative EPC possible or will the rest have to be tuned hydraulically?

[decipha]

No good, you eased in to the throttle and didn't finally go wot til 2400 rpm.
If you force static stall sw epc you can't adjust for the shift.
min clip isn't the problem if its banging sometimes and not others

I think your overthinking this. Give this a go and LMK.

[efloth]

Yeah, I have a tendency to do that. Not sure why I didn't think to use FN1420. Clutch bro! I'll try this out later on today and get a real WOT pull.

[decipha]

wot pull is fine but not necessary as its in power enrichment now.

[efloth]

Still shifting hard into 3rd and 4th. Should I just pull another 30% from fn1420?
Also, did you disable MPG mode for any specific reason?

[decipha]

it sounds like the converter is staying locked during the shift making it bang

force the converter to stay unlocked and see if thats it

cant dial in the ve table if its in OL, u can enable it if youd like you should be all dialed in

[efloth]

You nailed it. Not sure why it's not always unlocking for the 2-3 or 3-4 shift

Making progress on my hold 1st gear patch. I simply set the delay shift timer back to its initial value each pass. This works beautifully but on decel she freewheels and then acts like she's in neutral. I have to shift in to 2 and back to drive to get power from the engine again. Looks like I need to activate the coast clutch in software. Does that make sense? Ok to just turn it on like it does in third or vss fails?

COAST CLUTCH CONTROL
OVERVIEW
The coast clutch is a clutch used to provide engine braking in 3rd gear when
the PRNDL is in the drive position. Without the coast clutch the
transmission would free-wheel in third gear while the vehicle was coasting.
* In overdrive, the coast clutch is hydraulically off. Engine braking is
provided by the overdrive clutch in fourth gear.
* In drive, the software turns on the coast clutch to provide engine
braking. A short delay is provided to allow the overdrive clutch to
release fully.
* In manual 2 or 1 the coast clutch is applied hydraulically. Intermediate
band application is delayed until the coast clutch actually engages as
inferred by the shift in progress timer. This is to prevent the
intermediate band from absorbing excessive driveline deceleration energy
which could be better handled by the larger coast clutch.
* If the vehicle speed sensor has failed, the coast clutch is applied in
all gears below fourth to provide engine braking and prevent rapid
free-wheeling downshifts to first gear when the throttle is closed.