it doesn't have anything to do with the car, its because the motor is dawing so much current when you punch it, that the receiver isn't getting enough power so it kicks into fail safe mode, the capictor stores engery, so when you punch it, the receiver still has enoguh power to not go into fail safe, a stock motor wont draw as much amps as a 19 turn will, so thats why it works with the stock motor,
like i siad, i'm almost positive that will solve your problems, and for the $6, if it doens't work its not the end of the world,