Pathfinder / qx4 Re4r01a transmission problems

[Idrive4fun]

I have searched around and cant find any information on the form's.

 

I have a 2002 infinity Qx4 I have been told it is the same thing as like a 2001 pathfinder.

 

After doing research I think its a Re4r01a transmission. It's a 4 speed automatic with reverse.

 

The other day I noticed reverse started slipping. Also when I shifted into reverse when cold the transmission would slam into gear.

 

All forward gear's worked up until a few months later. when reverse started slipping badly then all of the sudden the transmission got weak.

 

I think it's stuck in 2nd gear. It will not shift even if I drop to low. Transmission fluid is full checked on level ground w/ car running and worm.

 

Here are the codes that are present

 

P0731

P0731 (Pending)
P1110 (Pending)

P0430(Pending)

P0325

P1448

P0455

P1110

P0420

 

I know some of these codes have to do with oxygen sensors. I have replaced all of the sensors with new ones and I'm still getting codes. I think I saw a TSB on the ecu about that.

 

 

[Snorf]

P0731 is First Gear Malfunction

 

Possible Causes

• Shift Solenoid 'A' is stuck in open position
• Shift Solenoid 'B' is stuck in open position

Setting Conditions

Engine running; vehicle driven at a steady Cruise speed, and the TCM detected an incorrect voltage condition on the 1st Gear circuit. Note: During this test, the CCM monitors the Actual gear position by checking the torque converter slip ratio. The slip ratio is calculated as this equation: A X C/B (where 'A' is the output shaft revolution signal, 'B' is the engine speed signal from the PCM, and 'C' is the gear ratio inferred TCM from other inputs. If the Actual gear ratio is higher than the gear position (1st2nd) inferred by the TCM, the slip ratio will be too high. If the slip ratio exceeds a certain value, the TCM determines that a fault exists and signals the PCM.

 

Looking into this a little bit i found Multiple cases of a bad alternator causing this code and messing with the fuel trims (possibly the problem with the o2 sensors?).

 

P1110 Is Related to the Variable Valve timing. The solenoid is electric controlled and regulates oil pressure to the actuator. Dirty oil, failed component, and improper voltage can effect this.

P0420 and p0430 are Catalytic converter efficiency codes. Computer reads the o2 sensors to determine if converters are working. if theres a problem with the 02 sensors it can mess this up, usually it means your converters are bad.

p0325 is a knock sensor code. These codes are pretty rare, ive never seen one as a mechanic.

P1448 is a evaporative emissions code related to the canister vent control valve being stuck open. May be completely unrelated to other codes.

 

I think the first thing i would do is check the alternator output for over-voltage condition and for a/c ripple. both can really screw with electronics on the car.

If no problem is found start addressing them one at a time.

If The engine is running poorly it will effect the shifts of the transmission.

Disconnecting the transmission connectors should put it in limp mode. you will have one forward gear and reverse. If its still slipping in reverse without the electronics hooked up you have an internal trans problem.