Transmissions software update and Fluid change
 

Due to a tech at my Acura dealer takung too long (over 1 hour) to rotate 2 tires (yes you read that right) the service manager asked my wife what could they do. She called me and I reminded her about the TSB that we were out of warranty for. $300 dealer value. We had the fluctuation in rpm's between 10mph and 40mph. It was absolutely awful driving I wanted to get rid of truck. Driving for a few days after service is done there is ZERO judder and rpm fluctuations. Drives like new.
btw my wife didnt go off on the manager and he said that because she was so calm and was not disrespectful to his staff it was his pleasure to offer her a service. Being nice does payoff.

I did the same firmware upgrade on my 11 MDX back in 2014 and it was a big improvement. Finally started to get normal mpgs on the hwy compared to upper teens.

After the update what MPG were you averaging? Mine seem pretty low.

I was getting around 17-18 mpg on the hwy before the firmware upgrade. The speed limit is 75 mph (set cruise at 80 mph), 5000-7500 feet, and can have a lot of downshifting because of inclines. The MDX felt a little smoother with the shifts and less downshifting on inclines after the firmware upgrade. I can see 21-23 mph at 75-80 mph when I can stay in top gear for hours on level ground. City mpgs are about the same at 15-16 mpgs at 100% and 17-18 mpg combined at around 50/50 driving.

Thanks for the info

Tranny back to fluctuating RPM driving between 20mph and 50mph. SMH

If it happens after the software update and ATF change then next step/service bulletin is to flush the transmission fluid. Snapshot required if still under warranty. This is caused by ATF deterioration under certain driving conditions so they say. Honda/Acura is specific about their procedure but I personally think a trans flush machine is a better option. I can confirm this fixes the issue.

i can do my own 3x3. I'll knock that out in the next weekend or so and see what i get from it. Thanks for the background information with your experience.

I never needed a software update, but before you begin the gravity drain and fill process, check the ATF level on the dip stick and after you come back from the first gravity drain sequence "drive".
Many have added an external cooler (radiator bypass), so measure how much old ATF came out and put that much back in. Torque = 36 ft/lbs.
After you gravity drain the ATF you need to circulate the new fluid with the old.

When you take it for a "spin":
Step 1. Start the engine and slowly shift thru all of the gears, then turn off the engine.
Step 2. Repeat Step 1.
Step 3. Put it in 1st gear and drive slowly to 2500 rpm. then stop.
Step 4. Put it in to Drive and slowly speed up and feel each shift point, then stop.
Step 5. Repeat Step 4.
Step 6. Go to a large parking lot and make a back up move that is 50 feet long, then stop.
Step 7. Repeat Step 6.

You have completed the first gravity drain and fill sequence.

Now this is just me, as preventive maintenance...At 100,000 miles (2007 MDX) I changed the 3 transmission sensors (myself for $50 each).
The two on the top are # 28600-rke-004 and the one behind the driver's tire is # 28610-rke-004. I used 3 each new washers # 90471-pw7-a00 and torqued then in at 14 ft/lbs (the same as if they were spark plugs.).

Did you complete the fluid exchange?

I know the RPM fluctuation you're talking about. I did a 1x3 DW1 ATF change and it went away. Drove it for about 300 miles so far and I'm about to do another 1x3.

Acura does have a software update that will fix the reving RPM and also the ticking sound heard on 2014 MDX's.

This ticking noise you speak of is a normal characteristic of the direct injection system. 2014 and up, they all do it.

Did a 1x3 and it has helped along with a freah oil change. I still 3 more qrts to do another tranny fluid change. Shifting much smoother again