Engine/Transmission (1994 - 1998) same old shifting problem

[Swineheart]

I still have the tach jumping all over the place and funny shifting problem. I changed the CPS and gapped it correctly. The dealer said a bad alternator could be giving voltage spike to the PCM making it shift badly, so I changed the alternator Know change. So what do I look for next any ideas I am getting tried of throwing parts at it.

 

[Missouri Mule]

The tachometer could be bad. There is a way to check it out but I don't know it. If tach is bad it won't affect trans performance. My tach in the Freightliner jumps arounds or misreads a lot but does not effect the manual trans or engine (24 valve/vp44/ECM).

The engine speed sensor (cps) sends a signal to the PCM which the PCM interprets than sends a signal to the tach. The PCM also uses the signal (data) from the engine speed sensor to determine the use of overdrive gear.



The PCM could be faulty.

The Throttle position sensor could be faulty.

Throttle cable could use adjusting.



Did use scanner(or key method) to see if you had any codes?

 

[BSander]

Is your torque converter going in and out of lock up? If it is, try this:



Follow these instructions http://www.suncoastconverters.com/im...d rewire.pdf



When I did this, I soldered the connections, soldered the ring terminal to ground and put it on the driver's side with the ground strap from the battery (the ground strap that goes from the battery to the rad. support) Basically, you are cutting the wire and grounding each end of it. Follow the directions exactly.