Gear Shifting Issues and Multiple OBD-II Codes on 1997 Nissan Pathfinder

[Starburst]

Hello ,

 

Good morning / good afternoon,

 

I'm experiencing some issues with my 1997 Nissan Pathfinder (VG33E engine) and could use some advice and insights. I'm really stuck now and don't know what to do, and the mechanics I've gone to haven't been able to help.

 

• Gear Shifting Problem: After driving for about 5 minutes, especially during stop-and-go traffic, my car (automatic transmission) encounters a problem when the speed reaches around 40-45 km/h (25-28 mph), which I believe is in the range of shifting between 2nd and 3rd gear. The RPM goes up to 5000 or more, and the car doesn't go any faster than 40-45 km/h. Sometimes, after a couple of seconds, the gear changes, but the shift is hard, and it goes back to normal. However, recently, it has been getting stuck at that speed for a while. My workaround is to stop the car, shift to N, turn off the engine, then turn it on again, shift to D, and the car goes back to normal until it happens again.
• Poor Acceleration: The car's acceleration is not as strong as it used to be.
• Fuel Efficiency: A full tank gets me around 200 miles, and I only drive in the city.

 

Although I'm not getting any check engine light, my OBD-II scanner has pulled up the following codes:

• P0325: Knock Sensor 1 Circuit (Bank 1)
• P0720: Output Speed Sensor Circuit Malfunction
• P0734: Gear 4 Incorrect Ratio
• P1105: MAP/BARO Pressure Switch Solenoid Circuit

What Has Been Done So Far:

• Speed Sensor Replacement: The mechanic replaced the speed sensor, which fixed the non-working speedometer issue.
• Throttle Body Replacement: The mechanic replaced the throttle body.
• Knock Sensor Replacement: The mechanic informed me that he also changed the knock sensor.

 

Thanks in advance for your help! Your expertise and suggestions will be greatly appreciated.

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