false knock on 3-2 downshift?


Well-Known Member
Jun 16, 2001
Im having a problem with false knock. It happens mostly around 50-55 or so when it drops into second i see 20+ degrees of knock and the car just bogs and goes nowhere. I believe its false because at 45 i can drop it manualy into second with a small amount of throttle and i saw 38* of knock. Other wise the car pulls strong all the way into OD with no knock. The tranny downshifts and upshifts very hard but only seems to do it on the 3-2 downshift. I know its false, but nothing hits the frame and it has a poly motor mount on the drivers side, and new tranny mount as well. What other stuff should i look for? The motor does not move at all while brake boosting in drive or even reverse, nothing moves or seems to vibrate. Can i get a chip that would ignore knock for the first couple of seconds during a WOT run? Thanks for any ideas :)
The usual culprit is the down pipe hitting something. Frame, heater box, upper control arm, header tubes, etc. There's a lot of places it can that you can't see without a lot of crawling around in and under the car.

Having only one poly motor mount isn't going to prevent a good bit of motor "roll". If both mounts were poly, the motor WILL NOT "roll" around under different condions of positive or negative torque.
Jack the rear tires off the ground and run it. If its still doing it you should be able to see whats banging and causing it while someone else runs it up to 55mph and downshifts it. Good luck.