Hi,

My MPV 2003, 164K miles, started suddenly to have hard shift, from 1st to 2nd, 2nd to 3rd. Higher gears are smoother, but a bit of shock exists. The lower gear shocks are big enough that I do notice and feel like somebody bumped from the back.
I have changed transmission oil already (which didn't really change much, but got a bit better). The OBD reader appears to show MAF is responsive to acceleration, but I don't seem to get correct voltage at the harness from MAF (I do get 12V power and ground ok on the harness). As such, I am now suspecting MAF may be faulty (but not raising any engine code).
I also lost OD function around the same time. I found a similar symptom youtube on a Ford engine that had lost OD function with hard shift. His MAF harness was broken (mine is still ok), but since the symptom is exactly the same, I will replace MAF to see if that helps.
Anybody else experienced similar? What else would you think I should try?

Thanks.

 

Just to comment although 6 months after the post.
Use Synthetic Transmission Fluid along with 16 oz. Bottle of Lucas for high mileage Transmission additive.
This worked on my 2001 Mazda MPV.
Very smooth shifting now as the hard shift from 1-2 gear is completely gone.

 

Had the same issue, Mine ended up being the knock sensor. Once it was replaced van drove with no issues.

 

What is a knock Sensor?

 

What is MAF?

 

A knock sensor is a sensor that detects the knocking vibration of the engine with piezoelectric ceramics, used in spark advance control, will contribute to the improvement .and fuel economy of the engine performance. They bolt to the engine block.