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Discussion Starter #1
I thought that this would be a good topic to have in the Gen 1 MDX Forum.

Abridged Version from jw02.

".....I have a 2002 with about 90k. The torque converter appears to hunt in and out of lockup when in D5. I can see the tach and hear it shift about every second or two. It started about a year ago when driving around town at about 40 mph. It has been slowly getting worse, happening up to about 50 mph. I avoid it by driving in D4.

I bought my 02 MDX in 2004 with about 35k. The Trans recall was done prior to my purchase. I change the transmission fluid as scheduled, religiously, due to what I read here.

The constant shifting is fairly subtle. The tach jumps up and down about 200 rpm (say from 1800 to 2000 to 1800, etc), about every second at times. I can hear the engine change tone a little as it changes rpm, but nothing like a rumble strip sound. "


http://www.mdxers.org/forums/58-transmission-problems/37757-d5-lockup-hunting.html

I'm having the same issue and was wondering where jw02 made the voltage measurements from while he was driving? Does anyone know?
 

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Discussion Starter #3
I've done a 2X in the last few weeks. I'm curious if I could have a malfunctioning tc lockup solenoid or something else.
 

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Have you tried repeating the issue while driving in D4 and D3? I believe 4th and 5th gear are overdrive gears, and the torque converter has issues locking up when the transmission is moving into and out of those gears at around 40 mph.

If driving in D3 solves the issue, I have two recommendations:

1. Look into changing out the 3rd and 4th gear pressure switches. This issue wasn't uncommon on the early first generation Honda Pilots. In addition, the 3rd generation Acura TL automatics didn't have the best reputation for reliability, so a lot of members on acurazine.com would actually replace their pressure switches as a preventive maintenance item. There's a chance that only one of the two pressure switches have gone bad, but you might as well change out both while your at it. It's not a difficult DIY job and the parts cost to change out both should come out to be a little under $100.

2. Change the ATF again, maybe two more times. Honda fluid should be fine but I personally am not afraid (and actually prefer) to run a compatible aftermarket fluid. From what I've seen, it looks like the recommended ATF change interval from Honda/Acura is a little too long. Fresh fluid seems to have helped to resolve this issue in some cases.

If these don't help, then your issue might be tied to something else. I don't know how much mileage you have on your MDX, but the vehicle is already over 10 years old.


Good luck and please let us know if you plan on trying these fixes.
 

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It would be a REALLY good idea to get an HDS (Honda Diagnostic System) hooked up to your car and see if the TC solenoid is being commanded on and off. That would point you back toward the TCM or sensor giving the TCM bad information. If the TC solenoid isn't being commanded on and off, then I'd guess that you have a bad TC solenoid (which can happen when they get gummed up and get stuck in between on and off position).

There are HDS clone systems out there for pretty reasonable prices, or maybe a local MDXer might have one you could borrow / rent. It's really indispensable for running down a shifting issue, as you can see the state of every solenoid and sensor in the transmission real-time when you're driving the vehicle (I recently helped a buddy with an Odyssey - had to replace the TC solenoid, though only because it was connected to the solenoid that was actually causing other problems).

So with an HDS hooked up, you'd just drive the car at 40mph until it exhibited the problem, then look to see if the TC solenoid indicator was flipping between green and red. You might be able to figure out a way to clip a couple wires onto the TC solenoid connector, and run them into the cockpit and monitor the voltage with a meter - but I suspect that would be a little fiddly.
 

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nanstedt,
What you are experiencing is pretty normal if you did not have the transmission reprogrammed after 2013. I had the transmission computer flashed by the dealer, they charged me an hour labor saying that it was past the window. I was ok with it because I had them put in a battery and I got a loaner. Plus it was the only time I had my MDX at a dealer in my 7+ years of ownership as I do all my own work, so didn't expect anything for free.
After the transmission program update, the TC lockup in D5 has moved up to ~55mph when it was ~40mph prior to the update. Even with the update, I have been driving in D4 for over 120Kmiles with no problems other than a slight loss of fuel economy that is returned with an increase in usable power. D4 will lock the converter at ~62mph and unlock it when speeds drop below 55mph unless throttle position is increased to the point where the TCM unlocks it. I don't even use D5, its a slug and I'd rather spin the engine 500rpm faster than have it constantly shift anytime i hit a slight grade. YMMV
Derek
 
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