hey all,

im after some info about the auto tranny from any shop manual. any would be handy. if anyone would be kind enough to scan some pages and post them it would help heaps. :D

What exactly are you after?

i got ford and daihatsu ones if ur interested :P

back home gave some cars a thrashing :) ...... "hey look at that magna" screeeching past 5,500rpm :P ahahaha

anyway im after the electronic aspects of it, ie. is the solenoid controlled by PWM or current controlled etc

what are you going to do if u need to increase the voltage to the solinoid to make it change gear quicker? and good with op amps?

i rember one of my mates insisiting the magnas of this year were did not have computer controlled auto boxes (both carby and EFI). i go ok watch this, i removed the fuse for the "4-AT" under the dash, started the car and i go plant it. tranny went into "limp mode" stayed in 3rd gear, did not shift up or down. he shut up completely. it is not mechanicaly controlled.

as for increasin the voltage / current i think that would fry the solenoid if anything and stress it too much. based on what many other cars do the more current the tranny comp gives to the solenoid the smoother the shift is (theres obviously some limit as the ecu would fry + the solenoid).

just need to confirm if you need to reduce the current to achive firmer shifts (pop a variable resistor in series) - easier, OR alter the width of the pulse from the tranny ecu to the solenoid - bit harder (still do-able). either case its a square wave being outputed.

im 90% sure its the first one. i mean this ecu was made a while back and would not have elabourate features like modern tranny ecus which learn, its fairly basic.


see attachment - that is PWM (Pulse Width Modulation). an example how it works. the width of the pulse varies. in our case want the pulse to be smaller. current based tranny ecus have the same consntant pulse BUT the current varies in effect altering the the duty cycle of the solenoid. (ie top/bottom of wave reduced).

its one of these methods for sure. lookin at the attached image below..... say the ecu is outputting 12v to the solenoid @ 10% duty cycle, the voltage the solenoid would get is 1.2v, for 50% duty cycle 6v, and 90% duty cycle 10.8v.......... get how PWM works?

get some probes in there and have a go urself. if there needs to be an amplify of the current, post what you think it needs to goto and ill design a little circuit for each of the solinoids. they will use the imput from the ecu out, then amp it to whatever u choose (variable by a potentiometer as before) then into the solinoid. shouldn't be hard either way.

its either that or u might find the solinoid controls a pison, and to increase change time u can bore the feed into the piston out so the solinoid can depress and press faster

yeh no probs. ill get the multimeter out and do some current and resitance measurments to see how it behaves. should be quite fun developing a shift kit for a magna :)

things i will do;

1) measure the internal resistance of each solenoid (will vary but not too much say by 1-2ohms from base resistance).
2) current range (ill drive the car and get someone to know what the current varies to the solenoids for example 0.6 to 0.9 amps)

with that you can work out the voltage (v = i * r ) operating range.

ill watch the amps on the multimeter as i shift to see if the current to the solenoid goes up or down on how hard i shift or how slowly i shift. im still betting on the fact that less voltage/current to it produces firmer shifts.

once thats all down pat, then an appropriate resistance can be chosen to add an resistor in series. from experience with other cars your stock 1/2, 1/4 watt resistors will get too hot and fail. need a MINIUM of a 10w wire wound resistor (jaycar have them). should ge warm but not hot. and a switch to bypass it so you can select "stock shifting" or "firm shifting". yeh a pot would be ok but you would need to order one from a specalist electronics place (one that can handle a fair wattage), so ill play with the best resistance values / recommended, and get a fixed resistor (cheaper too!). max $1-2 + switch :)

ill get them to shift on the just on the point of feeling "harsh" and back off a bit.

ill do some measurements over the comming days.

the attachment is the idea im going for. (this is an example for 1 solenoid 1->2 shift, same will apply to the 2->3 shift).

sounds good...i remember when i wanted to do stuff to parents ford electronic shift kit was the plan...till i got the magna.