Help!!! I can't figure this one out

[DarkMesa8]

When I'm on the nitrous in third gear with my 95GT AODE, the tachometer will stand still while I'm still hauling @$$. Speedometer is going up quicly, but the tach is just kinda hanging around 4500 rpms.

Is this the factory tach just f'ing up on me? Or is it possible for an automatic to slip badly enough to keep the rpms constant while still accelerating the car rapidly at wide open throttle?

 

[sea ya]

dude i dont think your slipping that bad,you wouldnt be going
anywhere imo...i'd say tach,my phantom @ 6k is like
7k on stock tach "got both" good luck chuck

 

[Mike86Stang]

agree'd get an aftermarket tach, stock tach's are known for being inaccurate

 

[dragstang88]

if the engine speed is still increasing, the tach will still go up regardless of wether the trans is slipping or not. If you can hear the engine speed increasing and the tach is still staying still, your tach is just bad.