I just bought this car recently. It is a 2002.5 Protege5 with automanual/tiptronic. Odometer reads 112K, believed correct. Here is a description of the issue, and what has been done so far.
DESCRIPTION OF ISSUE:
When letting off the gas pedal, in auto mode, the trans sometimes does an unnecessary downshift, sometimes hard, and sometimes this is followed by shifting back and forth searching for proper gear. This can be from 4 to 3, or from 3 to 2. This is only in auto mode. In manual mode, there is no noticeable transmission issue. Other than this, shifting up through the gears in auto mode is normal with normal shift points and no slippage/flare and no hard shift. A possible related symptom: taking the shift lever from into R (car stationary, level, from N or P) there is sometimes a hard shift into reverse, i.e. the trans jerks on engaging reverse instead of engaging smoothly.
ATTEMPTED REMEDIES:
1. Transmission fluid had wrong color, wrong smell, and wrong consistency. Performed standard service on the trans. Drain, open, replace filter, close, refill 3 qts, then bleed one quart at a time through cooler hose until it all turns pink (five quarts needed). Verified level at temperature. Used Mercon V. No previous problems with Mercon V in five years with 10 Protege fleet vehicles.
2. Replaced the pulse generator with pulse generator from working car. Pulse generator is located on top of trans and can be accessed by reaching down between air intake hose and engine. No effect.
3. Took out and cleaned Vehicle speed sensor - sludge deposited on tip. VSS is located down low on rear of trans and can be accessed from under car between firewall and trans. When removing VSS have a catch pan available as trans fluid will pour out of the hole if car is not level. Did not have replacement VSS available, because only available car has ABS and ABS cars do not have a VSS on the trans, just a plastic plug in the hole LOL!!!! Cleaning VSS had no effect, so will swap with working VSS at earliest opportunity. ADDED LATER: I did swap the VSS from a good car and this had no effect.
4. Inspected motor mounts and found significant wear. Replaced trans mount and front and right motor mounts - so the engine and trans are supported adequately. Rear motor mount looks ok on close inspection so will not mess with that one. To give you an idea, here is what two of the mounts looked like:
As you can see from the condition of the mounts, whoever owned this car before me did not place a high priority on maintenance. DO NOT RUN YOUR CAR WITH MOTOR MOUNTS IN THIS CONDITION, OR BAD STUFF WILL HAPPEN!
Replacing the mounts reduced overall vibration in cabin and did reduce the sensation of jerks from the transmission but did not eliminate them.
Anyway thanks for reading, fellow Mazdaheads, and if anyone has any bright ideas, do let me know.
ADDED LATER: PROBLEM SOLVED
There were in fact two problems in tandem. The first problem was bad transmission fluid. This caused the downshifts to be "hard." Thorougly flushing the trans fluid resolved the hard shifts. But it did not resolve the other problem, which was incorrect downshifting behavior/seemingly random downshifts. It appears that this problem was caused by an incorrectly mounted Throttle Position Sensor (TPS). It appears that the tooth of the TPS was not mated correctly to the slot on the throttle body. This caused the computer to misread the throttle position, and order inappropriate downshifts (basically this was a kick-down happening whenever I let off the gas!) I reached this conclusion deductively as there was no way for me to reach it by direct observation. Here's what I did: I removed the TPS from the throttle body for testing and inspection. It checked out ok. But then I quickly realized there was almost no way to re-install the TPS correctly without removing the entire throttle body. So I removed the throttle body, installed the TPS on it correctly, then re-installed the throttle body. Afterwards the transmission worked correctly, with no more improper downshifts. The transmission is now running exactly the way it should run, with the only change being remounting the TPS (not quite - i did disconnect then reconnect the throttle cooler lines, and I did disconnect then reconnect the throttle cable - but these changes seem inconsequential). Ergo, the TPS was not correctly mounted previously. Whoever had installed it previously probably did it without removing the throttle body, and got it wrong as a result.
THE MORAL LESSONS OF THE STORY:
There are some very interesting morals to be drawn from this story. I will leave them as an exercise to the reader.
