Disabling the Multi-Displacement System (MDS) in a Ram 1500 primarily involves electronic modifications using specialized tuning devices or aftermarket modules, though some temporary manual workarounds exist.
The MDS system, designed to improve fuel economy by deactivating cylinders during light-load driving, can be turned off for various reasons, such as achieving a consistent exhaust note, enhancing power delivery, or addressing concerns about engine wear.
How to Permanently Disable MDS
To permanently disable MDS, you typically need to modify the vehicle's Powertrain Control Module (PCM) or Engine Control Unit (ECU) settings. Here are the most common methods:
1. Using a Tuning Software (e.g., HP Tuners VCM Editor)
This method involves connecting your vehicle to a laptop running specialized tuning software.
- Process: With a tuning suite like HP Tuners VCM Editor, you can access your Ram 1500's engine parameters. Locate the specific "switch" or setting related to the Multi-Displacement System. Once you disable this setting in the software, you must save your modifications. The final step involves "writing the file" to your vehicle's computer (PCM/ECU), which will then permanently turn off the MDS function.
- Pros: Offers complete control over various engine parameters, allowing for custom tuning beyond just MDS disablement.
- Cons: Requires technical knowledge, specialized software and hardware (often sold separately), and may void your vehicle's warranty.
2. Aftermarket MDS Disablement Modules (e.g., Tazer Mini/Lite)
Several companies offer plug-and-play devices that connect to your vehicle's OBD-II port.
- Process: These modules are typically designed for easy installation. You plug the device into your OBD-II port, navigate through its menu (often displayed on the vehicle's dashboard or the device itself), and select the option to disable MDS. The device then sends the necessary commands to your PCM.
- Pros: User-friendly, typically reversible, and does not require a laptop or extensive technical knowledge. Many claim to not void the factory warranty, but always verify with the manufacturer.
- Cons: Can be an additional cost, and functionality might be limited to pre-programmed options.
3. Custom PCM Tuning
For those seeking comprehensive performance enhancements, a custom PCM tune can include MDS disablement.
- Process: You can purchase a pre-flashed PCM from a reputable tuner or have your existing PCM tuned by a professional. This involves modifying the PCM's software to optimize performance and can include permanently turning off MDS.
- Pros: Tailored to your specific vehicle and modifications, often comes with other performance benefits.
- Cons: Can be expensive, almost certainly voids your warranty, and requires sending out your PCM or visiting a tuning shop.
Temporary Manual Workarounds
While not permanent solutions, these methods can temporarily prevent MDS from engaging:
- Tow/Haul Mode: Engaging the "Tow/Haul" button on your dash (or shifter) often keeps the transmission in lower gears longer and can prevent MDS from activating. However, it's not designed for regular driving and will affect fuel economy.
- Manual Gear Selection: For Ram 1500 models with an 8-speed automatic transmission, manually selecting a specific gear (e.g., 8th gear) using the gear limiter buttons on the steering wheel can sometimes keep MDS from engaging, as it forces the engine to operate outside the MDS activation parameters. This typically involves selecting a gear that keeps the RPMs higher than the MDS activation threshold.
- Cruise Control at Higher Speeds: In some models, using cruise control at higher speeds (e.g., above 85 mph) might keep the MDS from activating due to the consistent power demand. This is not a reliable method and depends heavily on driving conditions.
Why Disable MDS?
Many Ram 1500 owners choose to disable MDS for various reasons:
- Consistent Exhaust Sound: MDS activation can cause a noticeable change in exhaust tone due to fewer cylinders firing, which many enthusiasts dislike.
- Smoother Power Delivery: Some drivers report a slight hesitation or transition when MDS engages/disengages, and disabling it can result in a more linear power feel.
- Perceived Engine Longevity: While MDS is engineered to be reliable, some owners have concerns about potential long-term wear on components related to cylinder deactivation.
- Performance Driving: For spirited driving, consistent power output from all cylinders is preferred.
Potential Downsides and Considerations
- Fuel Economy: The primary purpose of MDS is to save fuel. Disabling it will generally result in a decrease in fuel efficiency, though the exact amount varies.
- Warranty: Any modification to the PCM/ECU, especially through tuning, can potentially void your factory powertrain warranty. Always consider this risk.
- Cost: All permanent methods involve an upfront cost for hardware, software, or professional services.
Comparison of MDS Disablement Methods
| Method | Description | Pros | Cons |
|---|---|---|---|
| Tuning Software (e.g., HP Tuners VCM Editor) | Electronically disable MDS by modifying a specific "switch" setting in the vehicle's engine control unit (ECU) software, then saving and writing the new file to the vehicle. | Permanent disablement, highly customizable, can optimize other engine parameters. | Requires specialized software and hardware, technical knowledge, potential warranty void. |
| Aftermarket Modules (e.g., Tazer) | Plug-and-play devices that connect to the OBD-II port to modify ECU settings, including MDS disablement, often reversible. | Easy installation, user-friendly, reversible, often retains warranty (check specific product claims). | May cost more than other methods, limited to available features, some models might not be fully supported. |
| Custom PCM Tune | Professional modification of the Powertrain Control Module (PCM) by a tuner, often done in conjunction with other performance upgrades. | Optimized for specific vehicle modifications, permanent disablement. | Requires professional service, potential warranty void, often more expensive. |
| Manual Workarounds (Temporary) | Activating Tow/Haul mode, manually selecting gears (e.g., 8th gear in an 8-speed transmission), or using cruise control above 85 mph (if applicable to your model). | No cost, no modifications needed, easy to engage. | Not a permanent disablement, can affect driving experience (e.g., higher RPMs in Tow/Haul), MDS will re-engage when conditions are met. |
Ultimately, the best method depends on your technical comfort level, budget, and desired outcome.
