5.7 Hemi Eco Mode Problems – Symptoms and Solutions

The 5.7 Hemi is your go-to when it comes to having a powerful engine possessing plenty of horsepower and torque with a high level of reliability to boot. However, there are times when you don't necessarily need all the power that it offers, so that's where the Eco mode really comes in handy.

Key features and my opinion about the engine

• Production years:2009-now
• Average lifespan of 5.7 Hemi:220,000-250,000 miles
• Fuel supply type:port injection
• Power range:355-395 hp
• Fuel efficiency:bad
• Engine block material:cast iron
• Engine reliability score:high
• The most common problems:you will need thin oil, otherwise lifters will die, EGR problems, exhaust manifold problems, Hemi ticking noise issues.

Common Complaints about the 5.7 Hemi Eco Mode

In this article, we will look at the common problems experienced by owners of Ram heavy-duty pickups with the 5.7 Hemi under Eco mode, such as:

• Power Loss in Eco Mode
• Eco Mode Does Not Activate or Deactivate
• High Fuel Consumption Even When in Eco Mode

We will show you the possible causes of each issue and the corresponding solutions you can apply to get your mind off this matter in no time.

Power Loss in Eco Mode

One of the common inconveniences complained about by owners of trucks with the 5.7 Hemi is power loss when in Eco mode. Before we proceed though, maybe it's a good idea for us to have a recap of what Eco mode does first to shine a light on the matter for those who are either curious or confused about it.

Eco mode in the 5.7 Hemi is designed to improve fuel economy by reducing engine power and throttle response. It does this by retarding the ignition timing and closing the throttle slightly when you're not pressing on the gas pedal.

This operation can result in a slight reduction in performance, but it's hardly noticeable unless you're really pushing the engine hard. Basically, Eco mode can help you save a little bit of gas, which is always a good thing.

It's not really clear how Eco mode relates to the MDS or Multiple Displacement System of the Hemi apart from the fact that they are essential for fuel savings because Chrysler is a bit vague about how their connection. Some say that they are the same, and some think they are distinct from each other but with a common purpose.

What makes people think that the Eco mode and MDS are different is that each has a separate indicator and there are times when the two don't activate at the same time. In some instances, their indicators turn on one mile per hour apart. There are also times when the Eco mode is off but the MDS is still active.

From what we understand, MDS is a fuel-saving technology that allows the engine to run on four cylinders during light load conditions. When you're just cruising along at low speeds, MDS kicks in and shuts down two of the cylinders. This reduces fuel consumption and emissions, without sacrificing any power or performance. When you need more power, like when you're accelerating or towing, all eight cylinders are automatically engaged for maximum performance.

Based on this, we surmise that the two are definitely distinct from each other but with complementary functions wherein both are aimed toward bringing about fuel efficiency. In addition, it is worth noting that the Eco mode focuses on the throttle and ignition timing response while the MDS centers on the operation of the cylinders.

Nonetheless, both offer a seamless transition that you'll barely even notice unless you're paying close attention to your fuel economy. And speaking of fuel consumption, the 5.7 Hemi with MDS can get up to an impressive 25 mpg on the highway.

With that, it is only normal for a little reduction in power when under Eco mode. However, if you think that the power gap is significant enough, you might be looking at problems related to neither the Eco mode nor MDS.

There are a few things that can cause major power loss in a 5.7 Hemi engine. It can be one or a combination of the following:

• Incorrect spark plugs or spark plug gaps can cause misfires and loss of power. The solution is to check the spark plugs and make sure they are the correct type for your vehicle. Also, check the spark plug gap and make sure it is correct.
• Dirty or fouled spark plugs can also cause engine misfires and loss of power. The solution is to clean or replace the spark plugs.
• A weak battery can result in starting and charging problems, which can lead to power loss while driving. The solution is to test the battery and replace it if necessary.
• A faulty ignition coil can trigger misfires and insufficient power. The solution is to test the ignition coil and replace it if necessary.
• Vacuum leaks allow unmetered air into the engine. This can cause the unit to run lean and produce less power. The solution is to find and repair any vacuum leaks.
• If the fuel injection system is not delivering enough fuel to the engine, it will run lean and produce less power. The solution is to check the fuel system for any restrictions or blockages.
• If the exhaust system is restricted, it can cause a loss of power. The solution is to check the exhaust system for any restrictions or blockages.
• Engine overheating will not only result in performance loss but it can also heavily damage it and cease its function. The solution is to check the cooling system for any leaks or restrictions.
• Dirty or contaminated oil can cause a loss of power. The solution is to change the oil and filter according to the manufacturer's recommended schedule.
• Worn or damaged engine parts can impede proper power delivery. The solution is to have the affected parts repaired or replaced by a qualified mechanic.

Eco Mode Does Not Activate or Deactivate

Another complaint linked to the 5.7 Hemi's Eco mode is its tendency to malfunction. According to some users, there are instances the Eco mode fails to activate when running at low speeds or it fails to deactivate when power is needed the most.

This problem shares the same causes as the previous item, including dirt, faulty fuses, low battery, worn wiring harnesses, defective spark plugs, deteriorated air filter, and sealant leaks, among others. It could also be rooted in a throttle issue. Make sure to clean the area that you suspect is causing the issue or replace the worn components to fix it.

The culprit could be the PCM or power control module of the 5.7 Hemi engine, too. A malfunction or wrong calibration in the PCM can result in various errors in your vehicle's onboard tech. Have it recalibrated so it could effectively manage your vehicle's performance-oriented functions. However, if the computer continues to produce errors, try resetting it. If the problem persists, consider having the PCM replaced.

Fuel Consumption is High Even When in Eco Mode

One of the main reasons your 5.7 Hemi might be consuming more fuel than usual is that the Eco mode isn't engaged properly. In order to get the most out of your engine, make sure that the Eco mode is turned on whenever possible.

If your Eco mode is working well though, another reason for increased fuel consumption could be due to a dirty air filter. A blocked air filter will restrict airflow and cause your engine to work harder, which will use up more fuel. Be sure to check and clean your air filter regularly to keep your fuel consumption low. Likewise, refer to the possible solutions in the previous items if the problem is linked to the spark plugs, filters, battery, ignition coil, injection system, exhaust, contamination, and engine parts.

If you're still seeing high fuel consumption despite taking these measures, it's possible that there is a more complex issue within the engine itself. Consult a professional mechanic to diagnose and fix the problem so you can get back to enjoying your 5.7 Hemi's great performance.

Our Final Thoughts

The Eco mode certainly helps a lot in reducing fuel consumption in the 5.7 Hemi during instances where low torque is only needed. However, there are still some complaints attributed to this feature. Some of which were mistakenly blamed on the tech while others can be directly linked to it particularly its malfunction during crucial times.

Regardless, make sure to regularly check your Eco mode's status to avoid any unnecessary inconvenience and costly repairs. Refer to the diagnostic and troubleshooting guide we have talked about here to have any problem related to the performance of your vehicle fixed before the issues start to spread in the other sensitive parts of your engine.

We hope this article has helped you become more familiar with your 5.7 Hemi engine and its Eco mode function.