Torque Converter Lockup Behavior

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jonstamos

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Hello, first I wanted to mention that this site is a great resource and that I have been a long time lurker for many years. Usually I can find the answers with a little searching, but this time I'm looking for feedback and finally inspired me to register and join the community.

I have a '97 Mark that I purchased in San Diego before taking it back east to Maine. Last winter I did a complete front suspension overhaul that resolved my biggest annoyance; the clunking of the worn ball joints and the stiffness of the steering. Now I'm moving on to my next annoyance, the lockup behavior of the torque converter.

The torque converter in my Mark will unlock at highway speeds whenever I let off the gas. More annoying is the delay and momentary flaring of revs before the converter re-locks when I accelerate again. Since there are many hills in my area my daily commute goes something like this: Reach top of hill, take foot off gas, TC unlocks and engine braking consequently diminished, go faster downhill then every other car on the road necessitating braking, reach bottom of hill, back on gas, engine flairs then TC locks up, climb next hill, rinse, repeat.

I have found some posts on another site that say this is normal behavior, I would like confirmation that is true from other owners. If this is normal behavior, then I assume this behavior could be modified with a flash? Is the fix as simple as keeping the converter locked at all times in 3rd and 4th? I would appreciate any experiences people have had with mods that fixed this behavior. I can't be the only one that is frustrated by this.
 
What are your average speeds on this road you speak of? Also, when have you last had the trans flushed out completely and refilled with Mercon V? Just driving normal, the OD will usually kick in at around 37 mph to 39 mph with very light acceleration.

What mods do you have and do you have any pics to show us of this car. Everyone on here loves pics, especially from anyone new. Show us something and tell us more about any mods you have.
 
mmmm, well that doesn't sound right. the revving flare doesn't sound good at all.
 
chris2523 said:
mmmm, well that doesn't sound right. the revving flare doesn't sound good at all.
Click to expand...

I'm guessing his friction material is about shot or maybe he's due for a flush or maybe just a whole trans swap might be in order and hunt down a 98 to install. Will require a harness re-pin or electrical internal swap. Both are fairly easy but the longer it is neglected, the worse it's going to get.
 
I would have to agree, it doesn't sound like a lock up issue. I would call Alan at dirty dog, see what he thinks. Could be worn out or simply a bad lock up solenoid.
A lot of what people talk about from the lock up is the "hunt for gears" feeling, it can be changed in the tune in the speed/time to engage/disengage for the lock up. You have to take it to someone who can do it or purchase the SCT software package.
 
When was the last time you had a fluid change and what kind of fluid is in it ?? Agree Alan is the transmission man.
 
Thanks for all the responses. Here are some answers to the various questions: The drivetrain is stock. The transmission was last flushed at 72,000 miles by a Lincoln dealer as a condition of purchase, that's approximately 45,000 miles ago. I do not know the fluid used. Typical roads speeds are between 55-65mph.

However, here are the reasons I don't believe the problem is related to wear of the torque converter clutch or transmission bands. The car has always behaved like this, that's at least 45,000 miles of constant, non-degrading behavior. The shifts and torque converter lockup are firm and quick at WOT, there is no slipping or shuddering. The shifts are smooth and quick under light acceleration, and yes the torque converter seems to lock between 35-40mph under light acceleration. The rev flare that i speak of is about 50-100rpms. If I remember to grab a usb to serial converter, I'll datalog the behavior using my OBDII scanner. I'll try talking to Alan and post any ideas he may have.

Here is the link I found with someone who had the same issue (it's good to hear this is not normal).
 
that's the way they are

that's the way they are man and i hate them unlocking ---- i was going to ask if anyone ever just put a ground switch on the lockup wire?? that way it would stay locked in 3/4 -- did that on my 83 trans am -- 350 lockup trans -- loved it -- use a double pole double throw and one could run in full lockup =1--- center off=2 --- position=3 for factory settings maybe ,,, like when the little woman was driving it---- if it didn't drive the brain crazy -- then you might be able to sub resistance to the open circuit fooling the brain -- like a light bulb something to simulate load on that circuit -- just thinking ,,,, seen it many times that i wished it had locked at a different time or not at all - ill be trying that as soon as it cools off where i can stand it in the garage :D

homer.jpg
 
diagrams

just wondering if any diagrams are floating around and wondering if you can pick up that wire at the brake peddle switch and ground it with a switch? -- wondering if it goes from the trans to the brake switch then to the brain to be grounded?
 
OK, so have a couple votes that this is abnormal behavior, and another that this is normal. Can any other owners provide some feedback? Does this happen on every stock Mark VIII or is it only for a select few?
 
Mine didn't do that stock when I got the car, after I changed the gears it did it quite a bit ("it" woulb be...like it was hunting for the right gear). I only changed the setting for the gears in the tune at first. Maybe it did it originally but I didn't notice it.
I went back in and changed the lock up strategy.. fixed now.
 
I think its normal. My 98 did that too. When the car is in 4th and you let off the gas pedal, it would take a second or so to lock back up. Its just your auto trans for you. My Lexus wit its 6-speed auto does the same thing.
92 LSC AOD is locked 3rd and 4th.

Personally I like the locking and unlocking of a torque converter, on a car thats not too powerful it gives you an illusion that you have more gears, requiring less down-shifts. Needless to say I would take a manual tranny over auto box anytime, on any car.
Now the amount of time for it to lock up is up to you to determine if its too long or out of tune. Also the factory tunning of the tranny is very sloppy. SCT tune or J mod would help things out a bit like others said.
 
I've always liked the way they unlock and coast. Thats part of why they get good gas mileage. My fusion with the cruise control on will slow the car down when coasting down a hill. I dislike that.
 
It's normal behavior, and yes - both of your questions are possible solutions:

1) You can get a tune that you can change the lock-up schedule with.
2) There is a way you can wire a switch into the lock-up circuit so you can manually keep it locked. In 3rd & 4th with this switch, the converter will stay locked, but in 2nd and 1st it won't because the valve body won't let it.

If you're interested in option #2, I have the plans somewhere and I will post them - just let me know...
 
jonstamos said:
The car has always behaved like this, that's at least 45,000 miles of constant, non-degrading behavior. The shifts and torque converter lockup are firm and quick at WOT, there is no slipping or shuddering. The shifts are smooth and quick under light acceleration, and yes the torque converter seems to lock between 35-40mph under light acceleration. The rev flare that i speak of is about 50-100rpms.
Click to expand...

Sometimes you answer your own question and don't even know it. ;)

I vote NORMAL. That flare that you speak of has always been exhibited in my car and any other 4R70W that I have ever ridden in or driven. It flares because the torque converter is unlocking and multiplying torque and then will lock again at which point the rpms will drop. The throttle input that you give the car to make this happen will depend on what speed you are traveling and where you are at in the shift schedule.

You can even see this happen during wide open throttle conditions when the converter locks in 3rd gear as seen here at about 5K rpms it falls back on lock-up:

https://www.youtube.com/watch?v=YtR--BKXWH8&list=UUzAG3n7bbZ39T3azT66TiEA&index=20&feature=plcp

Here is a tune with the no lockup in second and lock-up in 3rd much later. As you can see, even at just before 100 mph when it locks it will still exhibit the same symptoms:

https://www.youtube.com/watch?v=6aM8zGNhS1g&list=UULcKQK6EBQyKP6o_ewqlqdg&index=45&feature=plcp


So again, the flare is from throttle input by you that is momentarily unlocking the converter and the fall back of rpms will take place when the converter locks again.

Here is an example of probably exactly what you are experiencing:

Converter unlocking while driving - YouTube


And for what it's worth on the way down the interstate over to the track last year my car was doing that A LOT. Especially if you are at that sweet spot in the shift schedule where just a little bit of throttle will unlock the converter momentarily. If you are starting to climb a hill, it will definitely happen. Why? Because the amount of throttle input that is needed to climb the hill will automatically want to unlock the converter.
 
It's normal, at least in a Gen 2. The TC unlocks when coasting to save fuel. I agree it's a PITA, but it can be tuned out.
 
I find myself using the OD button a lot. It's quite a bit smoother than letting the car have it's way. I use it for hills and for slowing down when in OD. This pretty well eliminates any hunting.
 
DLF said:
It's normal, at least in a Gen 2. The TC unlocks when coasting to save fuel. I agree it's a PITA, but it can be tuned out.
Click to expand...

Those parameters were changed somewhat on my car when it was on the dyno. At lower cruising speeds in the city like around 35 mph my converter will lock completely and will take a very generous amount of throttle to unlock again. As a matter of fact if I want to pass someone at those speeds, most of the time I have to tap the brake pedal to command it to unlock.
 
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