Nisaja

Hello guys. I'm trying to help out a friend. The car is a 2004 JDM Automatic.

Problem -
The car's transmission behaves erratically. It would jump from 1st to 3rd, or hang in 2nd, not go out of 1st, etc. It has a mind of its own. Eventually, it stalls. It never stalls when in Neutral or Park. Only in Drive and Reverse.

What we've done so far -
Replaced AT fluid.
Checked all solenoids.
Replaced the wire harness that leads to the transmission.
Changed the transmission control module.
Changed the transmission 3 times! (I know)
Changed the engine.

He's about to swap the car's ECU, but The ECU he has in the car has the part number "N3H2", and the ECU he's about to use is "N3J9". Are they swappable?

Please help! This issue is driving my friend mad.

Nisaja

Anyone?

UnknownJinX

Are you sure it's the transmission?

If you shift the car manually with the paddle shifters, does the car run well without any codes?

Nisaja

No, shifting manually is still the same. The shifts are jerky. We took the car out for a drive on Friday. It was fine for the first 5 minutes. Shifted smoothly without a problem.

After like 5 mins, the shifts started to get really jerky.

3 mins later, the car lost a lot of power and refused to rev.

2 more minutes later, the car died. Couldn't start it back up for at least 45 minutes. It would happen gain after 5 mins of driving.

What could this be?

Loki

iTrader: (1)

Well a couple of things come to mind: this is heat related given that it drives fine while cold. The engine not restarting is more than a little strange since with the trans in P or N, the engine is free to do its own thing independent of transmission. Therefore the trans isn't fully disengaged. Could be one of the shift solenoids. You said you checked them, but how? Did you check them at operating temperature?

BigBadChris

iTrader: (4)

Blocked line to or from the trans cooler?

NotAPreppie

You've had cooling problems in the past. Were those resolved?

The engine not starting unless you wait 45 minutes make me wonder if you're still having a cooling issue. Have you check the coolant temperature sensor? How about the intake air temperature sensor (inside the MAF sensor)? When was your last compression test and what were the results?

Nisaja

Sorry for the late reply guys.

I'm not really sure. A Mazda dealer checked them. We ended up replacing the transmission. Still the same problem.

Checked cooler lines and transmission cooler flow.

No cooling problems. Car stays cool. Coolant temp below 220F. I couldn't check the IAT. Compression test hasn't been done

Nisaja

So my friend replaced the transmission and the engine AGAIN. This time, the car runs longer than 5 minutes, but at high RPM, there's a whine coming from the transmission. Sounds like a race transmission. The car also intermittently stalls when the RPM drops. Doesn't happen often. Once it stalls, you can start it back up almost immediately. There is no power loss however.

scottfetsh

did you find anything? mine is acting weird too, it has a bad delay into reverse that slams...ok bad tranny so i changed it now the new one is doing the same within 5k miles tcu? ok where is it and does it need to be programmed to the car?