I have a technical question concerning open loop versus closed loop.
As a few of you know, I turned my leased 2002 Scab 4.6 lariat in and purchased a 2002 Screw 5.4 lariat with 43,000 miles. In the 4.6 Scab that I had, when I would accelerate at WOT, the transmission would shift very firm, (which I like) and around town the trans would shift "wife friendly". No problem. In my new (to me) 02 Screw 5.4, at WOT the shifts still seem "wife friendly". Now, I thought at WOT, the trans would always make firm shifts as opposed to soft shifts, but this doesn't seem to be happening with my 5.4 Screw, but I've only went to WOT twice in the two weeks that I have had it. Could there be something wrong with it? The truck I turned in and my present 5.4 Screw have the 4R70W trans.
Maybe someone can shed some light on this?
I am totally cornfused................
Reloader

 

Open loop is @ wot and uses set A/F parameters and closed loop is when A/F is adjusted by data taken from the upstream 02 sensors

This has nothing to do with how hard or soft the shifts are.

 

I believe the stock program retards the timing a few degrees during upshift. Get yourself a tuner and that can be taken care of.

SL

 

I think your seeing a difference in PCM programming and possibly an operational difference in the same transmission type.
The larger engine makes more torqueso mayhave different programming in the PCM.
It can be changed but is expensive to do that small change.

 

One of the factors that controll one/ two shift are the springs in the one/ two shift accumaltor these springs are different from one truck to another no rime or reason for differance in springs, they go by trans. tag number and replacements may not be the same as origanal. This being said I guess I am saying you can't compare two trucks and expect them to shift the same.
Also when they mfg. these units some will have tighter tolerances than others.
When I installed my factory tech valve body I had to have Mike cut back my shift pressure at light throttle 2 or 3 times to get what i wanted. I wanted hard shift at wide open but crisp shifts at light throttle. Mike was able to acomplish this in his custom tuning. Hope this helps answer youre questions.

 

Hi Reloader,

This is very easy to take care of, just give us a call if you want a proper tune done on that vehicle to give it a much more linear shift characteristic without spoiling it's smooth character at lighter throttle openings, etc.

"Chucksbp" made a very appropriate comment regarding how there are some differences in how all the various different versions of the 4R70W are configured - and even what parts some of them get even in the exact same platform, like the F-150.

Also, there are strategy differences - for example, in the 4.6 V8's the torque management is not as pervasive, and more of them can go O/L compared to the 5.4's - however, there have never been any 1997-2005 F-150's that have ever had a correctly operating transmission in stock trim that have had what could be described as a "firm" shift at full-throttle - they simply don't do that unless something is wrong, or they have been modified. that being said, of course there is a wide range in what some consider to be "firm," and I have no doubt whatsoever that you are in fact feeling a significantly "softer" shift at heavy throttle in your latest truck - most likely due to a longer shift duration, more pervasive torque management, and some other aspects to involved to get into here.

The 5.4 really doesn't make "significantly" more torque @ WOT @ 5000 rpm than the 4.6 does, but their torque management is more pervasive there, absolutely. Yes, the 5.4 certainly makes more peak torque than the 4.6, and it makes significantly more torque at lower rpms - of course, it's got a 4.16"+ stroke! But it's torque at WOT @ 5000 rpm is not that much more than the 4.6 motor.

There can be other considerations - for example it may be that your 5.4 truck's strategy doesn't even allow it to go O/L at all, and thus doesn't even make it's rated peak power - it happens. That too, is easily taken care of.

All in all, it's easy for us to understand what you're feeling, and yes, that can easily be taken care of for you - just give us a call at our number listed below and we can go over the details with you.

So hang in there, we can make that truck so you'll enjoy it's shift characteristics (and a lot of other aspects) more enjoyable & responsive than what you have right now, without the wife complaining or having problems swapping ends over a gear change in the middle of a tight turn in the rain, etc., etc. Setting up a nice linear shift calibration is easily done.

Best of luck whatever you decide, & hope you enjoy this next F-150!