It's ALive - FrankenJaguar has come home

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

After a marathon 4 day session fitting a 4L80E into my XJ-S at a friend who have a hoist, I have just driven it back home for the finishing up parts - putting the shifter and console back together etc.

So far I have the PCS TCU working nicely - it change into all gears, locks up the torque converter, the 1-2 gear shift is a bit hard, so I wll have to adjust it, all other gears are smooth. The tranny temp on the way home was around 65 Deg C on a 30 deg C day which seems to be a bit cool?

Final things to do are to connect up the speedo drive output from the TCU and get it to read the same as the laptop.

Once I have the fitted up the shifter properly and got the console back together, I will start tuning the TCU to what I want.

Thanks for all the help Russ.

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

Iain,
Glad to hear your up and running. Tuning the transmission should go pretty quick. Just be careful not to slip it too much. Adjust your shift firmness first, then your shift points, and last your TCC lockup.

Russ

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

Russ, I am having a problem with the starter inhibitor in P & N. I have set-up PWM 4 to PWM vs Gear, and set P & N to 100% ground output. ( Inhibitor Relay needs ground to start)

When I first turn the car on, the TCU reads the gear position as 1 , not P or N, it only goes to N once the car has started.

Does this mean I have to use a normal microswitch for the starter inhibitor relay?

Thanks

Iain

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

Iain,
The reason it doesn't work is because the 4L80e uses pressure switches to determine shifter position. Since there is no pressure in the transmission when the engine isn't running the controller doesn't know the correct gear.

Russ

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

Thanks Russ, I've wired in a microswitch for the P position until I can get the orignal linear switch for the shifter.

Next question, where do I find some information on how the 4L80E works, and what are the "safe" limits on the various settings.

For example, I would like a softer shift in 1-2 at low TPS - can I change the duty point up to 75% without burning out clutches etc due to excess slippage?

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

Ian,
I would recommend picking up a service manual that includes the fluid flow diagrams. The diagrams will help understand how the transmission functions.
The line pressure tuning can get a little tricky because the pressure to duty cycle ratio is not linear. From 100%-60% has no effect on line pressure, 60%-40% line pressure change is minimal, 40%-15% is the sensitive area, and 15%-0 line pressure change is minimal again.
To determine if the shift is too soft look at the Turbine speed response in a datalog. You can get actual shift time by looking at when the turbine speed begins to change to when it reaches the correct value for the current gear. An excessive shift time means the line pressure is too low.

Russ