Does the Prom Control the Shift points in a car? I know it controls the fuel/air mixture and the spark timing, but I'm not sure about the Shift points.
Basically my transmission is acting like crap, and the dealer near me who I have a 3 year warranty on the tranny says that because I switched the prom (305-350 engine swap so I switched it) the transmission shift points are messed up and there is possibly nothing they can do.. The only thing is the car has been acting fine for quite some time with that prom in it and only recently has the transmission been acting up.
Any advice??

 

No. Although the ECM does control the TCC (to which the ECMs VSS input is important). The two items that control the shift points are the TV cable adjustment and the governor (in the trans).

RBob.

 

Yes, find another mechanic. The ECM in our cars only control the locking of the TCC on an automatic, nothing else. There is no electronic shifting or setting of shift points on 3rd Gens, all shift points are controlled by the transmission itself.

I suggest you go to the Transmission Board to discuss tranny issues.

 

thanks.. now I can shove it in the dealers face.. I knew they were feeding me bs

 

Only to a slight degree.
In a nutshell a tranny references line pressure against govenor pressure to shift. Making a few more HP will raise the actual line pressure a little and raise the shifts slightly. And a bad chip will drop the shift points SLIGHTLY.

Tell em to fix the tranny.

If it was fine, and with no other changes took a dodo, it was wear that was the problem.

I'm not clear on if you changed engines, but a higher HP engine will kill a marginal tranny alot quicker then a low HP one.

 

yeah I switched from a 305 to a 350, but my 700r4 is brand new (old one died last year) and supposedly it's the automatic that is capable of handling a 350, so as long as it's under warranty it's good enough for me...