'97 XLT Auto Tranny-What Controls the "Shift Point"???

[rpr]

I've heard others say there XLT's shift at about 4,200 rpm. Well, if I accelerate hard (say 90%+ WOT), I get up to almost 6,000rpm before I have to let up on the accelerator and only then will it shift. I don't drive hard normally, so under normal driving conditions I really don't have a problem. Moderate to heavy acceleration is also OK. But when I really get on it, it seems to rev way too high. I'm not even sure if it would shift at all if I kept the pedal mashed to the floor, but I'm not willing to find out if that means making my engine scream at 6,000+ rpm for any extended duration. There is no "red line" denoted on my tach, but 6,000rpm is the max on the gauge.

So my question is, what controls the shift point on this tranny. Is it mechanical like the old days (ie: vacuum, which I highly doubt) or electrical (ie: computer chip).

Since I've heard other people buying a "super chip" to make the engine reach higher rpms before shifting, I assume it is electrically controlled through a computer chip.

So the real question is, do I likely need to replace my tranny (88K miles) or do I likely need to replace my computer chip??? A local shop told me there were no error codes stored in the computer chip, but I don't really trust this shop and I'm not sure if they actually checked (it was a "free service").

Of course I understand it probably could be any combination of a number of things, but if anybody can enlighten me on what (in theory) is used to trigger this tranny to shift, at least I would feel a bit better about understanding the problem before I start "investing" into this thing. Tx.

 

[Jason_25]

I don't think you have a problem at all. It's perfectly normal for the SOHC engine to reach 6000 rpm's before shifting. And the shifting is computer controlled.

 

[rpr]

OK, thanks for the reply!

 

[KCKExplorer]

You know, I have the same exact "problem", it just doesn't seem like it would be normal. I got a question for you though, my 97 XLT has 88k on it and I think it is shifting hard, but its always shifted hard... or seems like to me anyways. Does yours do the same thing, or anyone else's?

 

[TPLYNCH]

KC, have you had the tranny fully flushed and the filter changed?

 

[rpr]

Mine shifts fine 98% of the time. Every once in a while it will shift very hard, usually on a downshift. It worries me, but I'm not sure if there is anything I can do about it.

 

[Jason_25]

Maybe it's due to something in the drivetrain. Mine shifted extremely hard and it was because It needed new U-joints and a driveshaft yoke.

 

[ranger7ltr]

Have there been any changes in the wheels/tires/drivetrain at all? The tranny does shift electronically and the shifting is controlled by the PCM.

First, if there are not any modifications done recently, I would remove the battery cables for 30 min and then try to see how the tranny shifts then....

Second, if the shifting doesn't come back, I would flush and refill the tranny and replace the filter. Then pull the battery cables again...

Resetting the PCM can reset the shift points as well...If not, then you may be about to visit the shop of a GOOD tranny specialist.....