Ok i just got home i was in automatic, i made a left turn and started to accelerate nothing too hard got up to about 40-45 and all of a sudden the gear went down from 4 to 3 and knocked really hard. Does anyone know what this could be???

 

i maybe no genius but it sounds like you got a problem

 

well it depends do u remember what RPM u were at?

 

i get that too. but mine usually happens when im going uphill or something... and im at low rpm cuz of hill and 4th gear isnt going fast enough. so the cpu downshifts to use 3rd gear and gives higher rpm... giving you a boost.
I use tritronic sometimes to downshift when im not going uphill fast enough.
thats what happens to me neway its not a problem.

 

It happens because your Mazda3 designed to downshift for better acceleration, if you were in 4th and suddenly accelerated, the gear will down shift to 3rd and finish those high RPM's to a red line and shift to 4th, why? I guess its for the safety of your tranny and better acceleration. BUT the knocking, was it a sound that you mean or the jerk you had from the car accelerating? If, i want to gain some speed fast i shift to triptronic and go to 2nd gear, only if i am going less than 60 mpr, at this limit RPMs exactly 6500, and shift to third and so on. But the downshift is the nice feature, an I am sure all AUTO tran. cars do this too except that some won't have a digital gear display, where u can see what happened.

 

thats exactly right, the car will downshift from 4th to 3rd when accelerating in auto or tiptronic mode, depending on the rpm of the car at the time, since the car get to 118mph in 3rd gear, 4th gear is pretty useless since 118mph is the magic number for engine cut-off, or 7k rpm. if in 3rd gear, you can downshift down to 2nd at about 60mph and take it up to 80mph and then get back into 3rd. its a nice little pick-up at that time, especially freeway driving.

 

Honestly i am little afraid to push RPMs too high, just don't wanna blow my engine like i did on Corolla once, heh as for engine cut off i think i have to look that up, cause i want that switch off, any ideas?

 

You wont blow your engine running it a high RPM's unless you redline it ever time you shift, the worst damage you do if you run it at high RPM's it gets a little too hot, but if you dont take care of your engine and run it hard alot then it will blow, newer cars today (assuming that they have been put together right at factory, you may get a faulty one) dont have as much tendency to blow unless you run it REALLY hard and take bad care of it.

 

as for now, i dont know of any way to take off the rev limiter or remove the engine cut off function. due to the complexity of the engines computer, there is no chip available to get around it.