I have a 1987 4speed automatic cherokee that won't down shift to passing gear and if I take off to fast it bogs down and make a strange thumping noise. If I take of at a normal speed it shifts ok and I can get on the highway and go but again if I try to pass someone on the highway it won't down shift. The car had the heads and fuel pump replaced any ideas what could be wrong? BTW this car has the shift performance switch and it doesn't make any difference what position it is in.
Thanks,
Ed.
Doesn't it have that throttle cable going to the transmission? TV Cable? It might be out of adjustment or not connected maybe? Real easy to adjust! ;-)
AW-4 Transmission TV Cable Adjustment:
Shift the transmission in park and make sure the ignition is in the off position. Depress the cable release button, then push the cable conduit back into the sheath as far as it will go. Rotate the throttle lever on the throttle body to the wide open throtle position. The cable will ratchet to the correct adjustment point as the lever is rotated. Release the throttle lever.
You also have to make sure that you can achieve WOT when you step on the gas pedal.
Maybe the electrical connections are dirty at the transmission?
thumping sound might be a failing engine/trans mount and maybe a stiff U-Joint on a driveshaft? Check to see if any of the driveshafts have hit something and made it shiny or bent.
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