Goslowjimbo

I recently rebuilt the 4l60E in my 1997 Chevy Express. Everything went great - except when I get above 65 MPH and accelerate, the speedometer goes the wrong way and the engine will start being erratic (speed variations, missing?). If I try to accelerate faster than normal, the engine will pulsate with great speed changes. I can be over 80 MPH and still reporting less than 65 during these episodes. If I start coasting, the engine settles out and the speedometer tells me how fast I am really going. What gives?

FLT

iTrader: (1)

Due to the fact that you are having issues reading the speedometer, I would recommend looking at the speed sensor in the tail housing. Make sure that it did not get damaged and also check the wiring there as well. It is common to see a problem there after removing and reinstalling a transmission. If everything appears ok try to tighten up the terminals on the connector. If that does not help you could replace the sensor and the pig tail. Also make sure that the wiring that heads towards the engine bay did not get damaged during the RNR. An example would be the wires stuck in between the bell housing and the engine. Good luck. Vince

performabuilt

iTrader: (25)

You also may want to check all grounds to engine and frame since the engine running is acting strange also sounds like you may have failed to reconnect one or torn one loose/