The Torque Converter usually locks up above 45mph (72km/h). So, if you normally drive under this speed, then you are correct that, lockup or not, the point is moot.

Now, there are two reasons that I could think of that will result in the TC not locking up (there might be more but I can only think of two, being an amateur myself). First of all, the TC clutch may be worn out, in that case you have little choice but to replace the TC and the transmission since the clutch material is probably everywhere in the transmission by now, clogging up everything.

On the other hand, it might be that only the solenoid has burned out, in which case that can usually be replaced. For domestic cars I have owned before, specifically a Ford, that can be done rather quickly and inexpensively. However, I have no clue what's involved with the MDX, you just have to wait for better people to chime in.

If it's only a solenoid, and if (this is a big if) it's cheap to replace, what you plan to do (ignore it totally) could be "penny wise, pound foolish."

Good luck.

 

The tranny shop guy said 9/10 it's not the cheap fix and the tranny has to come out ($2000-3000) so it seems completely not worth it since the car hardly drives/tows at freeway speeds and I only intend on keeping it for 2 more years or so...

Do you know if the TC has a chance to lock-up AT ALL under a very heavy load at, say, 100 kmh? (60 mph). Anyone knows?

 

Yogi,

I don't know what year your MDX is, but here is the information for the 2001-2002 MDX.

You might have to drain the radiator and remove the radiator hoses to get to it since the TC lockup solenoid (and Shift Solenoid B) appear to be hidden beneath the radiator hoses. I can shine a light in there and see them, but there is no way my hands are small enough to get to them.

You can try measuring the resistance at the very least to see if it's within the range 12-25 Ohms. If it's open or shorted out, then maybe there is a chance for it.

Good luck

 

Wow, thanks. I was just gonna go to the Acura dealer to get the same info.

In the meantime, I found this (not specific to Acura).... Would that basically mean that under my not-so-light load , the TC lockup is completely inapplicable/irrelevant?

"The ECU will often lock up the torque converter when the car reaches a particular speed and gear but usually only under low load conditions. "

 

That's why you need a really big transmission cooler when towing. Heat kills transmissions. What year is you MDX? You still have not told us.

 

2003 MDX.

Yes, I do have a large aftermarket cooler. About 8x6 inches that sits in front of the rad.

 

this might be a silly question, but is an 8x6 cooler considered big?

I bypassed my internal radiator cooler and instead isntalled a 8 x 15 aftermarket external cooler. However, I always thought mine was on the smaller side.

Sincerely

 

And I've just found this to suggest even more that I should disregard lack of lock up.... (again, not specific to Acura)

"The TCC is made to engage usually only in the top gear when the car is cruising, not accelerating."

I never tow in the 5th...

 

The TCC will only engage under very light load, the slightest acceleration will disengage the TCC, think of it as an overdrive 6th gear. Strictly engineered to aid fuel economy, mass introduction in the early eighties on US domestic cars, along with mass failures/problems, although usually a failed solenoid in those days.

If I were in your position, I'd just drive it until a driveability problem forced me to repair or sell it. As always, YMMV

 

EXACTLY!

You guys have answered my questions... That was my thinking. TC lockup is completely inapplicable when towing a massive boat at 90-100 kmh (55-60 mph). So probably no reason to worry at all, kind of what the tranny shop manager said.

Much thanks guys. I am at a complete ease now (BTW, the shop told me that it would cost me the same to put a used tranny in later, say after mine dies, as it would to fix the no lockup issue now, if the tranny had to be removed). But at least I have a nice shot at spending exactly $0.

 

Use D4 for the towing.
You'll be totally fine without the TC working.
Do the 3qt change annually and you'll be good on heat with that size cooler.

 

Rally, this was precisely the plan. (and yes, I've already been towing in D4 and drained 3 qts annually), so I suppose no change to my driving whatsoever. I got an unintended crash course in torque converters because of my P0741 error code though. LOL. Too much knowledge can't hurt, I suppose LOL

 

OK guys something else is bugging me now, hope someone with more insider knowledge can explain.... if the lock-up usually occurs at about 50 mph or higher because at that speed there are less frequent wide-open throttle applications, why does the lock-up shuts off ("unlocks" if you will) if a driver, say, applies 50% throttle (assuming there is no downshift)? Since the lock-up clutch is already engaged and assuming the engine has enough power to accelerate without downshifting, why can't the torque converter lock-up clutch remain engaged while the vehicle promptly accelerates? Is the lock-up clutch not designed to withstand that much force, ie: is it only designed to work when very little throttle/force is being applied?

 

It's basically like trying to accelerate from a stop in second gear, engine is not in the power band needed to accelerate smoothly and will likely cause a shudder, which happens on many older vehicles anyway until the pcm decides the parameters for disengagement exist. The algorithms used in the software for newer transmissions with 6 + gears have gotten better and the time to switch states has become much shorter.

 

Yeah, I do stick my fingers in there too. LOL. Great minds think alike.

From what I heard... yeah the bottom rad cooler is useless for cooling (and super prone to catastrophic failures as you know, fingers crossed NOT with my new aftermarket radiator!) but I've read that it is advisable to have it... for the opposite reason! Ie. to bring the fluid to the normal working temperatures in Winter!

And that does make perfect sense. Basically coolant gets hot rather quickly on the MDX so it helps get the ATF warm as well. I seriously doubt is cools it at all (the idea is plain stupid, ie. hot fluid cooling another hot fluid...weird).

But unless you live in a warm climate, with your oversized ATF cooler, you might be running your tranny on the cold side! It may simply not have enough friction to heat itself up especially since the elimination of the rad atf cooler altogether.

 

But unless you live in a warm climate, with your oversized ATF cooler, you might be running your tranny on the cold side! It may simply not have enough friction to heat itself up especially since the elimination of the rad atf cooler altogether.

I live in Central Florida. Only hell consistently registers hotter temperatures. So I dont have to worry about the need for quick warm ups in the winter.

I agree with you on all points.

 

Lucky you, then! Yes, I have seriously considered bypassing the rad too, but living in a cold climate, I would have been doing myself, or my tranny specifically, more of a disservice. They should basically do a recall on those stupid OEM radiators that fail on just about everyone and in such a horrible way that the tranny may go bust at the same time (thank God my wife saw the puddle of fluid before I put it in D that day....).