What does the Autotrans Interceptor do?
The Autotrans Interceptor is an electronic "hack" that plugs into the transmission, and allows you to independently adjust two settings:
- line pressure
- Torque Converter lock-up delay
If you don't have a thorough understanding of how automatic transmissions work, it's hard to easily explain how it works.. but let's give it a shot ;)
Line pressure
Your automatic transmission uses fluid to apply and release clutches and bands inside the transmission. By adjusting the pressure of the transmission fluid (also known as "line pressure"), you can modify shift speed and firmness. The Interceptor only permits you to increase the line pressure over stock, so you can only make the transmission shift firmer/faster... not slower/softer.
By increasing the line pressure, the car spends less time between shifts or "slipping". As a result, clutches and bands may enjoy a longer life due to less wear and tear.
Increasing the line pressure too much may create harsh part-throttle upshifts, including "chirping" sounds, which usually come from the accessory drive belt, not the tires as you'd like to believe. It can also lead to premature pump failure, blowing seals, or even breaking of 'hard parts' such as solenoids due to excessively high line pressures.
The usual killer of automatic transmissions is heat.. so if you plan on running an Interceptor at a high line pressure for long periods of time, I suggest investing in an auxiliary transmission cooler. Consider it cheap insurance!
Torque Converter lock-up delay
The Torque Converter (TC) in the 4T40E transmission is a wonderful piece of technology. It features a clutch which enables the input and output shafts to lock together, linking the engine directly to the drive axles identical to a manual transmission's clutch. Normally, the Torque Converter Clutch (TCC) engages after a set amount of time, usually 5 or 6 seconds once the car reaches a good speed in third or fourth gear.
With this adjustment (which is hidden inside the case on newer Interceptor models), you can adjust the amount of time for the TCC to engage. The dial for this setting is now hidden, because it can take a lot of adjusting to get it "just right". Most people find it is good at the factory setting, which is around 50%. Some people prefer the ride with a shorter delay, or a longer delay. If you are going to play with this setting, be prepared to move it back and forth a lot in order to find that "sweet spot" that works for you.
Several owners have claimed 0.2 seconds off their quarter mile times with the Interceptor installed. Actual gains may vary between cars.
Personally, I experienced increased fuel economy, particularly with the TCC delay dialed down to the minimum setting.
The Interceptor does NOT adjust the shift points. This job is handled by the powertrain control module, and (as of this writing) is not easily rewritten.
