03 P5 surging / random AT trans downshifting

[c4racer]

So our Protege5 is doing something weird.

Steady state driving - say between 30-50mph the trans downshifts a gear and revs the motor - wife described it as surging - but I was riding along in the car the other day and what I mainly noticed was the motor reved up due to a downshift. The car was not accellerating during that time - more like a downshift and motor reving but maintaining same speed, then shifts back up to the next gear. Happens randomly. Trans works just fine otherwise. Car has 130K miles, trans fluid has been changed every 50K miles or so and currently using Redline synthetic. Does not seem to be a slipping issue - more like the trans is getting an inacurate signal to downshift. Isn't the trans pretty much controlled by the ECM? Or is there a separate computer that manages the transmission?

any idea what may be causing this?

 

[MP5stephen]

I've noticed that too, driving in the full auto mode(not manual). I will be cruising at a constant rate, and suddenly the transmission will randomly downshift and it makes a revving sound, but it doesn't speed up, then shifts back to a higher gear. I'd like to find the problem to this issue.

 

[c4racer]

hmm - wonder if there is a TSB on this issue and maybe a reflash at the dealer might cure it?

 

[SeR_Cyclops]

Sub.

 

[c4racer]

get the flashing AT warning light today. Trans has abnormally high shock going from N to D and also shifts harder. Goes thru all the gears and no slipping detected. Doing some light reading of the service manual, traced to a few possible causes including the various solenoids. So I checked the resistance and there is one way out of spec - 55ohms and the range is supposed to be 7-10. The rest checked out OK. The one with an issue is the pressure control solenoid, which sounds right - seems the line pressure is not in the correct range. The solenoid does click when applying batt voltage, but given it reads way out of spec I am guessing it isn't functioning correctly. Looks like I will be replacing this. Wonder how fun of a job this is going to be.....

 

[i12drivemyMP5]

Here, wonder not.......................

http://www.mazdas247.com/forum/show...w-to-Change-your-Valve-Body&highlight=lentech

 

[Merryfrankster]

Did the Pressure Control solenoid solve the problem? I am having the same problem.

ADDED LATER: I solved the problem and I posted the answer in another thread. If you are interested, look up my postings and you will find it.