Shifting problems...

[Silent Assassin]

My car’s transmission shift points are messed up. It won’t automatically shift to the next gear till it climbs high in the rpm band. It shifts at around 3200 rpms despite taking off normal and easing into the throttle. When going WOT, it will shift to the next gear at just 4000 rpms, bogging down after the short shift. Tranny also refuses to downshift when I get on it, just stays in the same gear. Anyone has had this problem, what could be the cause?

Btw, car is a bone stock 1994 with about 180K miles. Recently put in a new transmission cus 3rd gear was toast, but the car was acting this way before the tranny swap, so I’m afraid this glitch might kill the new tranny as well. The same MLPS on the old transmission was used cus the new one did not come with one, and I disconnected the IAC sensor because the idle would not drop below 1500 rpms. Could any of those sensors be the problem?

Any input greatly appreciated.

 

[NoLimit95]

Frogman, where are you when we need you?

 

[XLRVIII]

when the VSS( vehicle spped sensor) fails or a wire gets broken on trans removal, the pcm can no longer shift the trans based on MPH and it defaults to a RPM based shift schedule.

its called
RPM_BASED_SHIFTS_FAILED_VSS
THROTTLE POSITION-----SHIFT RPM
1023.9844---------------4200.0
750.0000----------------4200.0
600.0000----------------4000.0
400.0000----------------3000.0
250.0000---------------- 2600.0
100.0000----------------1500.0
0.0000------------------1500.0

at very light throttle it wont shift until 1500 rpms
if you push the gas pedal "at all" then it wont shift until somewhere between 2600-3K RPM

heavy throttle makes it shift between 4-4200 rpm

does that sound like what your car is doing?

if so...check/replace the VSS sensor, if that doesnt fix it..its gonna be a broken VSS wire

 

[XLRVIII]

Frogman, where are you when we need you?

he would be as useful as titz on a bull in this instance.

a "search nazi" wouldnt have a clue how to resolve this and would simply resort to insulting the poster, and suggesting a search...when the LVC search would be as useless as he was.

 

[NoLimit95]

he would be as useful as titz on a bull in this instance.

a "search nazi" wouldnt have a clue how to resolve this and would simply resort to insulting the poster, and suggesting a search...when the LVC search would be as useless as he was.

Could it be possible that the wrong year trans was put in, without the correct re-pinning being done? Also, could the wrong MLPS could be on the wrong transmission?

I'm just guessing here. Having the IAC disconnected can't be helping very much.

As for Frog, never heard useful info come from him, except to "search" and I have seen that more than a thousand times and not only from him. You're right Tommy, about insulting posters around here, it should stop.

 

[Silent Assassin]

Thanks for the responses guys. That sounds very much to what my car is doing.

Forgot to mention on my initial post that I used the old tranny's VSS because the new transmission is from a low mile 1998 Grand Marquis which I snatched from a local salvage yard for $250. Thats right, I did my homework before tackling the job and found out that the '98+ 4R70W is the way to go. All the proper procedures were performed; replaced the TCC sensor to one for a 1994 M8, changed the linkage to maintain the floor mount shifter, rearranged the electrical pins to specs according to THIS link, changed the VSS and gear for proper reading of the speedometer since our cars come with 3.08 opposed to. 2.73 gears in the panthers, and went ahead and drilled the separator plates for the j-mod as well.

Since I used the original VSS, I can see how that might be the reason why the shifting problem persisted. I'll swap out the tranny's VSS today and check for any loose or broken connections, hopefully that'll be the end of it. I'll keep you guy posted, and thanks again.