So this car shakes/ vibrates a bit at lower speeds. speed between 15 or 25 mph. Sometimes it feels like it actually slows acceleration or shifting. I have noticed that it does it more when it has shifted up to the 4 th gear(automatic) at slower speeds. I was thinking motor mounts, but they look okay. I watched the motor as someone put it into gear, to see motor movement. Didn't see much. Whats next?
Transmission feels strong. runs and idles very smooth.

 

When was the last tune up?
When was the last transmission service? What's the level of the transmission fluid? Observe reading procedures to the dot on top of the "i".
Are the brakes binding? Corrosion on the sliders could lead to such a situation

 

Everything was just done. And i mean everything.
Brakes are still 70%
Spark plugs and wires changed
All filters
Pcv
New CV axles
New front hub bearings
New struts
Coolant flush
Automatic transmission flush and filter change.
Motor oil and filter change
New tires and wheels all the way around

what more is there

 

What you describe could be caused by an engine issue or a transmission issue.

If the engine stumbles a little bit it could cause the transmission to shift down. That's why I am pointing to drivability issues. How about the EGR and the throttle body? How about back pressure from the exhaust?

If all the engine items are cleared we are looking at transmission and torque converter. Of course there is not a whole lot we can do. Check the fluid level (don't trust your mechanic blindly) check the new fluid for any signs of contamination(smell, color).

When you say the brakes are 70% that only means that the brake pads are fine. What you really want to know is if the calipers will release: Check the sliders for corrosion.

You can check if there are any codes stored or pending in the pcm.

Do you have a feeling if it is the engine or the transmission?

 

Calipers are fine. Brakes are fine. Checked all through them. Engine does not stumble. There just seems to be a vibration or shake to the car occasionally. I think it may be related to transmission. I can drop it into a lower gear manually and it goes away. It seems to upshift to the high gear quickly and then you get the shake at the lower speeds.

 

mazda3club.com has some alarming posts on 2004-2009 2.3 engines blowing up. go there and search 'blown engine'

 

Wow. I just looked at mazda3club.com and I am blown to bits so to speak. I don't post there but I advise anyone to report to Home | Safercar -- National Highway Traffic Safety Administration (NHTSA).

Some musings: Mazda was so so in the quality department until they partnered with Ford. That's when they got the zoom zoom mojo going. Ford sold their share of Mazda in order to save their own financial butt. Look what happens after Ford's pull out? Crummy exhaust design in some Mazda6, early rust everywhere, and now this. How would you like to be rear-ended because of a blown engine?

I am afraid they don't have the will or means to keep up with quality. If they loose their fans they can fold up.

 

Here's the crummy exhaust design that was on my Mazda 6 until I changed it. It actually caused misfires. Don't know who to blame, Ford or Mazda. This was not changed in 2007 on the V6 3.0 L. For more in depth on this: https://www.mazdaforum.com/forum/maz...-design-28940/
Early rust, yep got that too! Covered by my separate rust policy. Rust not just on my Mazda 6, but the 3's as well, especially around the wheel wells. Rust not applicable to people living in Texas, Arizona! For more on this: https://www.mazdaforum.com/forum/maz...zda-6-a-31330/

 

IIRC, Ford sold much of it's shares in Mazda around 2008-2009, but still holds 12% instead of the 30%+ they once did. So much of this is happening to cars made during the Ford era.

73Chalngr, Have you (carefully) cleaned to MAF sensor lately?