Fitting the TCU prior to fitting the 4L80E

Iain_B · New Member Joined: Aug 21, 2006 Posts: 12

I would like to fit the TCU into the car tomorrow, and tie in all the wiring external to the transmission. ( If I can find a connector and the new speed sensors arrive I'll fit the tranny next weekend).

I would like to fit everything, then when the tranmission is ready, just plug it in. Can I do this, and will I be able to see what the various sensors ( TPS, tacho, coolant, brake light, etc etc) are doing via the laptop screen

Is this recommended, or do you need to have the transmission hooked up to stop the TCU from frying itself?

Iain

Russ · PCS Employee Joined: May 12, 2004 Posts: 286

Iain,
You can connect the TCU without plugging into the transmission. You should be to connect with the software and see all sensor readings. You can also calibrate the throttle and enter your axle ratio and tire diameter.

Russ

Iain_B · New Member Joined: Aug 21, 2006 Posts: 12

TCU is up and running, talking to the computer and the tacho, TPS, coolant sensor is calibrated and brake pedal switch works.

The base setting seems very convervative, with WOT upshifts at 60 kph whilst the current TH400 upshifts at 110kph. I've changed some of the settings but want to make sure what I'm doing before going to crazy.

I'll rig up the digital inputs for Calibration B, No first, Upshift /Downshift tomorrow.

As far as digital outputs go, I would like to wire up the following:

1. Torque converter lock-up LED ( just for testing until I get everything programmed)
2. Calibration B LED ( to light up the Sports mode indicator on the dash)
3. Snow mode ( no first) LED also to light up the indicator on the dash
4. Output that goes high to trigger the electric fans based on coolant temp.
5. Output that goes high to trigger the electric fans based on ATF temp.

Is there enough digital or analogue outputs for all these and can some of the PWM output be programmed to act like simple digital outputs?

Next question, what function controls how hard or soft the shifts and how fast they are on the 4L80E, is it just line pressure, or does the 4l80E work off accumulator pressure as well.?

Likewise the torque convertor lock-up, what suggestions do you have for the lock-up settings. I have read the manual and the help file and all the post on this forum, but just want to be sure I understand how a 4L80E works just in case I do something that damages the transmission by mistake.

I would like the shifts to to fairly smooth at low TPS 0-35% like a Jaguar should be, but make it progressively harder up to WOT.

What is recommended for the torque converter lock-up, should I stay in lockup during upshifts/downshift or should I make it drop out of lock-up. What difference will it make ( will shifts be very hard in lock-up or will it cause extra stress on the rest of the transmission or on the TCC itself. I have upgraded the clutch to a carbon fibre clutch to take more abuse, but don't want to destoy it, especially since I have a high stall torque converter.

What are the key things that could break the transmission if I set them wrong?

Iain

Russ · PCS Employee Joined: May 12, 2004 Posts: 286

Iain,
The PWM outputs can function as digital outputs also. You should have plenty of outputs available to do what you want. The 4L80e uses 2 pwm and 2 digital outputs. This will leave you with 8 free outputs. You will need to use PWM outputs to trigger the fans. Setup the outputs as PWM vs Fluid Temp 1 and PWM vs Engine Temp.

The 4l80e uses only line pressure control for shift firmness and speed. There is no accumulator pressure control.

The 4l80e uses a pressure control solenoid for the TCC lockup. This allows the converter to be locked up smoothly. On most applications the TCC doesn't lockup until you get to 4th gear. The 4L80e allows you to lockup in 2nd,3rd, or 4th. Shifting during lockup should not be a problem for the transmission. However, the engine rpm will drop significantly during shifts if the converter is locked.

The weakness of the 4L80e depends on the vehicle type and power output of the engine. The only problem I have experience with is breaking the intermediate sprag from shifting too hard at light loads.

Russ

Iain_B · New Member Joined: Aug 21, 2006 Posts: 12

Thanks Russ, I'll make sure I don't shift hard on light thottle Very Happy

I've set the PWN to be 100% at 88 Deg C and above, and 0% at 76 Deg C and below, so it I'm right, then the fans will switch on at 88 degrees, but will they switch off 87 degrees or 76 degrees?

What temp to you recommend for the tranny fluid, I have a large cooler in front of the radiator and the one inside the radiator.

Russ · PCS Employee Joined: May 12, 2004 Posts: 286

Iain,
With those settings the fan should cut off around 80 degrees. I would try to get the transmission to run the same temperature as the engine. This will prevent the transmission from trying to cool the engine or the engine fom trying to cool the transmission.

Russ