I know I might be able to find this info in the Maxima service manual -- but I'll throw this question out anyway --

Does the torque converter go into lock-up mode via a centrifugal speed action or is it done by solenoids pre-programmed to engage at a particular engine speed?

On my car, it goes into full lock-up mode at about 3200RPM and higher -- I kinda wish it went into lock-up mode starting at a lower RPM --

 

The torque converter lockup is controlled by the Engine Control Module. Lockup occurs only in fourth gear and only when certain other conditions are met (engine warmed up, throttle not wide open, etc.) The lockup speed is not adjustable.

 

Try not to press the gas as hard . I when I had my '96 GXE, it would normally go into lockup after speed stablized a bit around 40mph IF I wasn't on the gas hard. Then when you want to accellerate, accelerate gently. Quick or harsh movment on the accellerator tend to make it unlock real easily.

btw, Dan's right, there' many parameters before the car will go into lockup. If the car isn't warmed up yet, it won't go into lockup until it's warm (presumably to help bring the catalyitic converter to operating temperature sooner by using higher engine rpm's.)

I don't know if the Max uses one, but many cars now use an adaptive system in the transmission ecu. It'll recognize how hard you normally drive and not lockup. If you have any auto, 2500 rpm or so should be about 70mph after lockup...

-V

 

So if what you all say is true, then I am not in full lock up mode in Overdrive until I get up to 90MPH at 3100RPMs --- That doesn't do me a whole lot of good for efficiency when I'm driving at 65MPH -- the posted limits around here --
Even at light throttle, the convertor doesn't lock up -- it just slips and slides and wastes energy

Even if it did full lock-up in each gear at those RPMs - that high of a lockup speed makes it very difficult to get the best mileage potential --- torque converter loss isn't exactly small either...

As far as those adapative convertors -- I personally feel that any convertor should be fully locked up all of the time unless the car is coming to a stop or when gears are being shifted -- The main priority of the torque convertor in an automatic is to keep the engine from stalling at a stop --- So why should any torque convertor be designed to waste significant fuel and power at virtually all cruising RPMs?

 

Auto designers do not agree with you. If they did we would not have torque converters on our cars, we would have simple fluid couplings like the Chrysler products did in the 1940s.

 

I've searched for the answer to this question and can't find any clear indication that the Maxima has an adaptive automatic transmission. Car makers that have this feature boast about it, and Nissan makes no such boast, so I believe Nissan does not have it.

 

You are correct.

My '99 Maxima factory service manual says lockup occurs only in fourth gear.

You are correct. Perhaps I should say "for all practical purposes lockup speed cannot be adjusted." This is in the same category as saying the speed limiter (in those Maximas which have it) cannot be bypassed. It can be, but it isn't practical to do so.

This is an intriguing idea, and there may be an easier way to do it.

Find the harnesses which emanate from the transaxle. One of them terminates in a brown plastic connector with eight pins. This is connector F42. With the engine off, disconnect F42. Hold the connector such that the plastic latch is at the top. You should now see two rows of four terminals. These are numbered (top row, left to right) 1 - 4, and (bottom row, left to right) 5 - 8. Terminal 5 is the power wire which controls the Torque Converter Clutch Solenoid Valve.

You run the risk of triggering the Malfunction Indicator Lamp and getting Diagnostic Trouble Code 1204 if you bypass the TCM and control the lockup manually.

 

I got a 1204 error code and found it was due to a bad thermostat. The lock up can only occur when the car is warmed up. with a thermostat that is stuck open, the car will cool while the Torque converter is in lock up and cause the error code. So if you get a 1204 code, watch your temperature for a bad tsat.

 

My 2003 SE AUTO hops when decelerating and passing through 40 MPH - kind of feels like what a manual trans does when decelerating. Dealer felt it, but had no solution. It bugs me so bad that I often leave car in 3rd until constantly above 45 MPH. Anyone else experiencing this and have a solution?

 

Let this 05/12/2001 die!

This is a 4th gen forum (1995-1999)

That shudder you are experiencing is the infamous fuel-cut programmed into the ECU between 37-42mph on all 5th generation automatic models (00-03)