Converter lockup

[umina]

at what speed should my torque converter be locking into overdrive? I find it pretty unusual that it will shift into overdrive in 4th at 32-33 MPH if I drive easy. Seems like it shifts too early and just lugs the motor. Is this normal? Every other car I've owned (including fords) have always shifted into OD at 42MPH, and shifted back out when slowing through 32-35MPH. I'm wondering if maybe my speed sensor is out of wack. The Speedo behaves normally and my cruise works (though I never use it regularly). I can also feel my car jerk when slowing down and the trans shifts from 2 back into one. i had a Stratus that did this for 35K miles when I sold it, something with the solenoid packs or clutch indexes being out of wack.
Any ideas would be appreciated.

Oh, the car is an '01 Duratec with 45K miles on it, its done this since I purchased with 36K a year ago. (the stupid things you don't notice on a test drive !!! :o)

[shorod]

My recall is that the Taurus needs to be "cruising" at a speed greater than or equal to 35 mph. Cruising implies that the speed and engine load is remaining constant for some amount of time. I'll see if I can find the info again.

I think that may have come out of my owner's manual, and I no longer have the car. Have you checked your owner's manual for a description of overdrive?

-Rod

[shorod]

From the service manual for the 2002 model year Taurus:
3) NOTE: Shift speed ranges are approximate for all applications. For specific applications (engine, axle ratio and application) refer to the Automatic Transmission Specification Issue booklet available from Ford Customer Service Division.
Apply minimum throttle and observe speeds at which upshift occurs and torque converter engages. Refer to the shift speeds chart.

[Chart shows 3-4 upshift occuring at 34 mph -- Rod]

4) Stop vehicle and move selector lever to D range. Repeat Step 3. Transaxle will make all upshifts except 3-4 and torque converter clutch apply should occur above 43 km/h (27 mph).

5) With vehicle speed above 43 km/h (27 mph), press the accelerator pedal to floor, wide-open throttle (WOT). Transaxle should shift from third to second, or third to first, depending on the vehicle speed. The torque converter clutch should release.

-Rod

[umina]

Thanks for clearing that up, I guess its shifting right where it should. Any thoughts on the 2-1 downshift jerk when slowing to a stop?

[shorod]

What condition is the transmission fluid in? Is it dark and/or does it smell burnt?

Does it downshift harshly all the time, or only when it's cold/warm, etc.?

The Transmission Fluid Temperature (TFT) sensor and engine coolant temperature sensors will cause the transmission to alter the shift agressiveness when the fluid and ambient temperatures are cold. Do you know which transmission your car has (AX4S or 4F50N)? There are quite a few potential issues that could lead to a harsh downshift according to the service manual. Without a scan tool to monitor the various transmission inputs and outputs, about all you can do is check the status of the fluid (level and condition).

-Rod

[umina]

Originally Posted by shorod

What condition is the transmission fluid in? Is it dark and/or does it smell burnt?

Does it downshift harshly all the time, or only when it's cold/warm, etc.?

The Transmission Fluid Temperature (TFT) sensor and engine coolant temperature sensors will cause the transmission to alter the shift agressiveness when the fluid and ambient temperatures are cold. Do you know which transmission your car has (AX4S or 4F50N)? There are quite a few potential issues that could lead to a harsh downshift according to the service manual. Without a scan tool to monitor the various transmission inputs and outputs, about all you can do is check the status of the fluid (level and condition).

-Rod

The fluid is good, I dropped the pan and did fluid and filter change in the spring, no metal in the pan, just a little bit of gunk on the magnet. Fluid is nice red color, does not smell burnt. I have the AX4N, transmission shifts from 2 to 1 the same regardless of cold or hot. It does shifter harder from 1 to 2 when hot though, like there is a pause before it shifts and seems like the RPMs drop off too sharply in between the shifts so there is good loss of power to get going again in 2nd.

I've often wondered if the car is running hot, the temp gauge in the car has never gone over halfway, and ist pretty much a smidge below half at normal operating temp, coolant level is correct and clean. I don't have a trans cooler on it, other than the stock radiator and tube in front, though I will be adding one in the spring. What sorts of things does the manual show as possible problems for the harsh shift? I red on TCC that there was a TSB on this, but no one had any more info.

[shorod]

In the electrical arena, the service manual suggest the following could cause harsh upshifts (not specific to any particular upshift):
Electrical inputs/outputs, vehicle wiring harnesses, powertrain control module (PCM), EPC solenoid, TFT, OSS, digital TR sensor, MAF sensor, TSS, IAT sensor, and ISC.

In the area of hydraulics, the manual lists the following:
FLUID: Incorrect level, low, condition
SHIFT LINKAGE: Damaged or out of adjustment
INCORRECT PRESSURES: High Forward Clutch Pressure, High Line Pressure, High EPC Pressure
MAIN CONTROLS: Bolts out of torque specification
Gaskets—damaged, off location
Main Regulator Valve, Backout Valve, Pressure Failsafe Valve
EPC Solenoid—stuck, damaged
2-3 Servo Regulator Valve, Engagement Valve, B3 or B2 Check Ball — missing, damaged
PUMP ASSEMBLY: Bolts out of torque specification
Porosity/cross leaks
Gaskets — damaged, off location
LOW INTERMEDIATE SERVO: Seals, Piston — worn, damaged
Fluid Tubes—damaged, loose, leaking, misassembled
Band, Anchor Pins
Apply rod—incorrect length
NEUTRAL TO DRIVE ACCUMULATOR: Piston stuck, Seals or Springs — missing, damaged
FORWARD CLUTCH ASSEMBLY: Check Ball
Friction Element — damaged or worn
Wave Spring — damage
Return Spring
LOW AND INTERMEDIATE BAND/REAR SUN GEAR AND DRUM: Friction Elements — damaged or worn
Drum — damaged


One thing I don't see in here is related to what the PCM does during a shift. I'm not sure how many Fords do this, but my '98 SHO would retard the timing during the shifts to reduce the engine torque and theoretically prolong the life of the transmission clutches and bands. Seems like if your Taurus would normally retard the timing, and for some reason it isn't doing that now, it may cause you to feel a harsh shift. Because the car is moving relatively slow for the 1-2 upshift, the harshness may be more pronounced at this shift than at higher shifts.

-Rod

[umina]

It must be something to do with high pressure somewhere. The reason I say this is the car makes a bang noise every time when put in reverse, and the motor doesn't move. motor mounts are good, but I think the bang is caused by the transmission or computer demanding full pressure when engaged. I'm sure this would cause other issues as well. When the torque converter locks up, and during the other shifts as well, the car pings during the shift point. I guess I just wait it out and see if she fails on me or not.

I own the car outright, but not sure if I want to drop 2K into a tranny rebuild or sell now while it still drives OK. I only put 10K miles or less on this car a year, driving it a total of 12 miles a day on back country roads at 35-45MPH. I figure if I do nothing, it should last awhile even though it is going to fail, but since its not abused or overheated or sitting in traffic, maybe i'll get another year or so out of her. Anyone had better luck with a rebuild, or replace with a remanufactured transmission, like off of Ebay?