c4 not shifting up at WOT?

[C0V3R]

Since I rebuilt the engine and gearbox (new seals mainly) I have noticed that the behavior of the c4 has changed. Initially at WOT it shifted at around 3800-4000 rpms which irritated me because it was too low. Over the first few hundred miles the behavior of the box has changed (slowly moving up the rpms) to the point where it now doesnt seem to shift upwards at all at WOT and I can be doing 5500-6000 rpm and need to lift my foot for a couple of seconds before it will shift.

Any ideas what's going on?

 

[enferno]

Since I rebuilt the engine and gearbox (new seals mainly) I have noticed that the behavior of the c4 has changed. Initially at WOT it shifted at around 3800-4000 rpms which irritated me because it was too low. Over the first few hundred miles the behavior of the box has changed (slowly moving up the rpms) to the point where it now doesnt seem to shift upwards at all at WOT and I can be doing 5500-6000 rpm and need to lift my foot for a couple of seconds before it will shift.

Any ideas what's going on?

only thing i can think of off the top of my head is either your band adjustmens, your kickdown, or your vacuum modulator.

 

[Rusty67]

Sounds like a vacuum problem. When I had my C4 in, I had a similar problem. Turns out my hose had come off.