Multi-Displacement System (MDS) in your Hemi engine helps with fuel economy, but sometimes you need full power. This guide provides a simple method to temporarily disable MDS on your Dodge or Ram truck.
Understanding MDS in Your Hemi Engine
MDS, or Multi-Displacement System, is a technology in Hemi engines designed to improve fuel efficiency. It deactivates four of the eight cylinders when full power isn’t needed, effectively turning your V8 into a V4. This happens by shutting down fuel injectors and closing intake and exhaust valves using solenoids. While beneficial for fuel economy and emissions, sometimes you need all eight cylinders working.
Why Disable MDS?
Disabling MDS allows access to the full power of your Hemi engine – maximizing horsepower and torque. This is particularly useful for towing, hauling heavy loads, or when you need quick acceleration. While a tuner can permanently disable MDS, this guide focuses on a temporary solution. Note that the tow/haul button only disables MDS on 6-speed transmissions; on 8-speed transmissions, it simply alters shift patterns.
Temporarily Disabling MDS: A Step-by-Step Guide
Disabling MDS temporarily takes just a few minutes and depends on your shifter type:
1. Center Console Shifter:
- Put the shifter into manual mode by pulling it all the way down and to the driver’s side.
- Pull the shifter towards the driver’s side and release six times. The number “6” should display on your dashboard, indicating manual mode is engaged for all six gears. This will deactivate MDS.
2. Rotary Knob Shifter:
- Press the “down” button on your steering wheel to activate manual mode.
- Press the “up” button repeatedly until the highest gear number for your transmission is displayed on the dashboard.
3. Column Shifter:
- With the shifter in “Drive,” press the “down” button to engage manual mode.
- Press the “up” button until the highest gear number for your transmission appears on the dashboard.
Once the highest gear number is displayed, MDS is deactivated, and your Hemi engine will operate on all eight cylinders. You’ll notice increased power and responsiveness. Remember, this is a temporary fix; MDS will re-engage when the vehicle is restarted.
MDS and the Eco-Light: Two Separate Systems
While the MDS and eco-light may activate simultaneously, they are independent systems. The eco-light indicates fuel-efficient driving practices, whereas MDS automatically manages cylinder deactivation.
Conclusion
Temporarily turning off MDS on your Hemi provides a quick way to access full engine power when needed. By following these simple steps according to your shifter type, you can easily control your engine’s performance. If you desire a permanent solution, consider investing in a tuner.
