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Discussion Starter #1
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.

Has anyone experienced this and can give me some info?

THANKS! :D
 

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Discussion Starter #3
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.

Thanks for your reply.
 

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Same symptons I had on my 03. Stll shifted ok, but left me with an uneasy feeling that it would totally go out at some point. After dealig with it for 30k miles, the dealer put in a new Torque converter. It's been fine ever since.

Note: I only had the rumbls strip sound one time about 30-40k miles ago and it never happened again so I never thought twice about it.
 

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Mine was covered under warranty, but I believe the total bill was about $2000, approximately an even split between parts and labor. If I can find the receipt, I'll post it exaxctly.
 

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Discussion Starter #7
Ceenit... from the looks of things, we have similar tastes in cars. I have a 2000 BMW 528, 5sp w/ M-package (love it!). I would love to add an early 70's 911 Targa to my too small garage.

I am cursed with the drive to fix everything myself. I am going to do a little investigative work this weekend to verify the TC is bad and not a control input or soleniod. If it is the TC, I may even try to replace myself (after reading the serv manual for signs of too many specialty tools).

Thanks again for the help!
 

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Discussion Starter #8
An update...

I measured the voltage supply to the Lock up solenoid with the following:
1. In D5, tranny and TC operating fine (cold engine), the solenoid voltage is just right... 0V not-locked, 13V lockup. No cycling
2. In D5, after driving a little, T/C cycling between lock and unlock, voltage = 11V ?????
3. In D4, tranny acts fine, voltage 0V all time.

The service manual states solenoid should be either 0V (no lock) or battery volt, 13V, in lock up. Any idea where 11V would come from? The serv. man. also states it should go into lock up in D4 too.

I am thinking the TC is okay. My problem is either the powertrain control module (PCM), or a crazy input. The PCM seems like the only thing that would give an 11V output and not allow lock up in D4.

Has anyone had to replace their PCM? Doesn't seem like a likely part to fail. Any thoughts????
 

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...or a crazy input?

As you stated, I see no reference to the TC Clutch Solenoid drive being anything but full on/off, even in the Partial Lock mode. That's not to say it isn't capable of a proportional output.

It would be tempting to explain 11V as a blown output device but you did see it reach full on in D5, at least when cold, and it’s not even trying in D3/D4. There’s probably more to it than that.

A semi-educated guess would still suggest the PCM is at fault, but that’s making assumptions on its behavior with as you said “A crazy input”.

Maybe an HDS diagnostic would shed some light on it?

Remanufactured PCMs look to be in the $300 range – Just don’t know if a Diagnostic could be had for much less.
 

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Discussion Starter #10
Thanks SDM. What is an HDS? Honda Trained Tech? I would have to check for a local expert, as it doesn't seem like just anyone would have this level of understanding. Any reputable sites you can recommend for rebuilt PCM's? I had a bad experience with MAF's for my sons Maxima.

If I can get the connector off the lockup soleniod (I could barely touch it and could not remove it last weekend. Maybe I'll eat my spinach Saturday), I thought to run a remote switch into the cabin and try energizing manually to verify all is well with the TC. I need to understand the logic more, to make sure there are no other signals going on at the same time. I don't want to freak out the tranny.

Anyone see any dangers in that move? It won't tell me what is wrong, but it could eliminate the TC and solenoid if it behaves properly. Thet biggest difficulty will be finding a level stretch of road around here. :D
 

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Anyone see any dangers in that move?

I don't know.

The A/T Clutch Pressure Control is also part of the lock up sequence and wouldn't guess what happens if things get out of sync.

Don't think I'd try it on mine.


HDS = Honda Diagnostic System

A comprehensive diagnostic tool used by Honda/Acura Dealers and well equipped independent shops. In conjunction with Service Manual troubleshooting procedures, it goes way beyond simply reporting DTCs.

http://techinfo.honda.com/rjanisis/RJAAI001_tools1.asp
 

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jw,
Any additional information on this topic?

I was thinking about putting a small LED in the dash that would illuminate when the TC relay or solenoid was engaged. That way I could monitor the operation to determine more information on the intermittent TC engagement.

more info from my post:
A new ECU Map is what I am waiting for.
Acura programed the trans to upshift to 5th as soon as possible for fuel economy. The Torque converter engages very soon after overdrive shift whenever the load is constant. I'm still unaware whether I get TC lockup engagement in D4 but that is what I use most of the time. I'm pretty sure it does lock in D4. My issue is that when driving in D5 at any speed ranging from 37mph to 47mph, the converter continually locks and unlocks. It is not something I can feel, but I notice the tach needle going up and down approx 200rpm. I spoke with my local dealer service writer and they told me I would need to leave the car with them to try and duplicate the problem. I know they will find no problem so I am waiting for the bulletin or map to be released. As of Friday, November 27, 2009 there were no recalls or bulletins regarding my vehicle.

2006
No known failure, vehicle acquired @ 54,445
Current Mileage: 60,500mi
TC locks and unlocks constantly when cruising ~45mph(D5)
Corrective action. none as of yet
Trans shifts great, delay when shifting into D
I operate vehicle in D4 until highway speed is @ or above 55mph, then shift D5 in order to preserve Torque Converter Clutch which is the underlying cause of the rumble strip issue.

The rumble strip could be clutch chatter due to a worn, overheated, or glazed friction material. The TC clutch slips and grabs, creating a vibration. Minor vibration may also be felt due to the fact that the converter may engage in D5 at speeds as low as ~35mph causing engine RPM to be at or below 1500.
 

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Discussion Starter #13
A few updates...

I could not duplicate the 11V to the TC solenoid again. My tap or ground wire must have lost a good connection the first day. So now it still goes in and out of lockup all the time, but it has a good 13V signal to the solenoid.

I took it to Acura service and they said I needed a new TC for $1600. I was not conviced, so I took it to a local transmission expert, explained my problem and he doubted the TC failure, as he has not seen much trouble with TC's on these vehicles (MDX, Pilot, Odessey). He wants to try a new solenoid and if that does not work, do some in depth diagnostics while driving. (Looking for a bad signal from something like the throttle position sensor, etc.

Too close to Christmas. I will continue to drive in D4 when not on the highway. Although it appears to be getting progressively worse.

Merry Christmas to all! :2:

RallyD, would you be near my old stomping ground... Hauppauge?
 

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A few updates...

I could not duplicate the 11V to the TC solenoid again. My tap or ground wire must have lost a good connection the first day. So now it still goes in and out of lockup all the time, but it has a good 13V signal to the solenoid.

I took it to Acura service and they said I needed a new TC for $1600. I was not conviced, so I took it to a local transmission expert, explained my problem and he doubted the TC failure, as he has not seen much trouble with TC's on these vehicles (MDX, Pilot, Odessey). He wants to try a new solenoid and if that does not work, do some in depth diagnostics while driving. (Looking for a bad signal from something like the throttle position sensor, etc.

Too close to Christmas. I will continue to drive in D4 when not on the highway. Although it appears to be getting progressively worse.

Merry Christmas to all! :2:

RallyD, would you be near my old stomping ground... Hauppauge?
Good Day jw02. Did you ever find a resolution to your D5 lockup hunting issue? I have the same problem with my 02. From where were you taking the voltage mesurments? I'd like to take some of my own.
 

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Same pattern in my 2005 from new. There was a PCM software update that I had done in 2013 that made a small improvement. Reference Service Bulletin # 09-037. Check with an Acura dealer to see if it was ever done. I should be free. Before the update, the TC would go into lockup at about 45 MPH on level ground at light throttle. The problem was that as I slowed down, it would stay in lockup until the rpm hit a bit below 1400. So, if I was going at 1500 rpm, the engine would lug. After the update, the point at which lockup kicked out became about 1500 RPM, so better but still not good enough IMO. I just got in the habit of staying in D4 anytime I was driving at 55MPH.
 

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I appreciate the suggestion but that TSB applies to the 05-06 MDX. Mine and jw02 is the 02 MDX. Since this thread is so old I'm wondering if jw02 still has this particular car anymore.. I cannot PM him as I do not have enough posts to do so.

Does anyone know where he may have taken measurements of the TC solenoid while driving?
 
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