It is with a heavy heart and a wounded pride that I have come here today. I have a problem and I quite simply can NOT figure it out. I only have two options on this. I will present the options, and then the problem.

#1: Keep plugging and hopefully figure out the problem and fix it.

#2: Tow the car to ohio(some 500 miles?) and have the guy who built the transmission make it work.


Here is the brain buster.

I have a 1995 Ford Thunderbrd LX 4.6L with a 2000+ 4R70W transmission out of a Crown Victoria. This transmission has the 8 tooth output shaft vs. the 7 tooth that my car came with.

The TC is a 2004 Mercury Marauder that has been rebuilt.

It has a modified valve body and different springs(shift kit).

I have repinned the harness to accept the transmission wiring pins and all should be well on that front.
I have rewired the entire EEC(computer), installed a speedcal, tried two output shaft sensors and two vehicle speed sensors.
I have a custom chip burned for the setup I have. The trans/gears/etc.


The issue is that when in D, it will shift 1/2 and 2/3 AND 3/4 all before 20 MPH and then fully apply the TCC.

So with that information given, I am asking... no... begging for someone to shed some light on this situation. I don't like asking for help, and I know this is a GM specific forum. I'm not starting this thread to hear any of the usual B.*. about how I should just get a GM. I just want honest to (insert religious/spiritual figure here) facts.

Thank you.

Could it possibly be a sensor causing it to shift that way? Sounds to me like a possible sensor failure. Or something might be wired wrong? I'm no expert

That'* the vehicle speed sensor. The output shaft sensor is on the side of the transmission. It reads the revolutions the transmission internals are spinning(variable on engine rpm and gear). The VSS does NOT have the correct speedo gear on it. I have a speedcal in place to take care of that. However, it may be spinning the speedo too fast at the lower speeds? I don't know. I'll put the correct gear on some day when it warms up here. In the mean time, I'm concerned about getting the thing rolling. Manual first and second work as they should. The O/D cutout switch functions properly and does lock out O/D. The computers(three different ones) have thrown no codes at all.

This damn thing has me lost.

On my year, everything comes directly from the EEC, with the exception of the spark... That is unimportant at this point though. I'd imagine the TPS is just like the rest of the car.... 183k old, with plenty of exercise from 150k(ish) to present. I'll put my volt meter on the TPS. You may be onto something. I forgot to mention that it WILL NOT downshift at WOT.

i tend to agree with the throttle positioning sensor theory. i dont know how the transmission works, so if you all can forgive my ignorance. tempo has the good ole mechanical throttle to tranny linkage. when the linkage is all the way out, the car drives like this. unfortunately, it is spring loaded for all the way open, and keeps coming apart <lucky me >. so i ask, this transmission doesnt by chance use a mechanical linkage or vacuum to determine throttle position does it?

The 4R70W is an electronically controlled transmission. It has no vaccuum lines, and the only mechanical linkage is for the shift lever. TPS sounds like a good cause to me. I will have to investigate when I get unlazy. Plus I don't like the cold....