I have tried over and over to find my problem and I have come to a dead end. I switched from a 2 port vacuum modulator to a 1 port and now the transmission wont shift when in drive unless I rev the engine to a ridiculous amount and it starts to creep and eventually kicks in and then drives. It drives fine after this until i turn off the car and restart it again and then the same thing happens. I replaced the vacuum lines, I replaced the new modulator thinking it was a faulty one, and no changes. I dont know what to do. It would shift into drive with the 2 port modulator and wasnt giving me so many problems. What stomps me is why would the 2 port work fine and the 1 port not work? Whats the difference and why is it doing this?
Well I dunno for sure but the pin that fits in modulator may be of different length... Also the OEM type single port modulators were adjustable via a threaded adjustment inside the vac port, too far in produces late/hard/no shifts...
