Cummins ECM: The Total Impact of Engine Performance

Cummins ECM: The Total Impact of Engine Performance



It's been nearly 25 years since the Engine Control Module (ECM) was introduced for semi-trucks. Since then, the ubiquitous ECM is the built into almost every car and truck manufactured.

Your ECM is one of the most vital components of your vehicle. It is responsible for interpreting data from various engine sensors to optimize fuel economy and power. Car and diesel truck controls are based on specialized, programmable computer chips.

Read on to understand how the Cummins ECM works and the ways it can be modified or tuned to improve engine performance.

What Does ECM Stand for in Cars and Trucks?

An ECM, AKA an Engine Control Module or Engine Control Unit (ECU), is a device that works sensors and actuators to control the performance of the internal combustion engine in a vehicle. They have been part of the modern engine since fuel injection replaced carburetors.

The ECU reads data sent it to it by sensors. Sensors provide data on air flow rate, fuel flow rate, and engine temperature and other inputs. These electrical signals are also kept as recorded black box data.

The ECM takes this electronic data and interprets it according to a programmed performance map. It then uses a series of actuators adjust the air-fuel mixture ratio or the idle speed of the engine. The idea is to bring your engine performance and fuel economy to optimum.

The Cummins ECM

A Cummins ECM is manufactured by Indiana-based Cummins, Inc. Apart from semi-trucks and other heavy-duty equipment, a Cummins ECM is found in General Motors non-commercial cars and trucks like the Dodge Ram.

The ECM in modern vehicles controls the safety system, entertainment and navigation and other electronic systems that are not engine related. A typical 1998-2000 era ECM controls and records more than 6400 parameters, a newer model just over 17,000.

ECMs record useful data for accident investigation from hard brake incidents such as speed, engine rpm, brake application, clutch position, engine load, cruise control operation, trip date, trip distance, fuel etc. A Cummins ECM captures up to three sudden decelerations, with data such as speed, clutch, brake, engine load, etc.

Non-Programmable and Programmable ECMs

There are two types of ECM: programmable and non-programmable.

Non-programmable ECM comes with a stock program from the manufacturer. It prevents unauthorized modifications in engine performance. Programmable ECM is adjusted to suit any aftermarket modifications the engine owner undertakes.

After an engine modification, a technician creates a customized performance map and loads an updated program to the ECM. This process is done via the use of a specially configured laptop. There could be more than 3,000 different timing tables to adjust, each with particular effects.

In addition to engine control, the ECM also controls the traction control system and stability control system. Fine tuning the ECM to driver behavior and other interactive systems takes experience and training.

Engine Performance and the Cummins ECM

The sophisticated algorithms of the Cummins ECM use sensor data to:

  • Improve Fuel Economy
  • Increase Engine Response
  • Reduce Emissions

However, poor or incorrect programming has negative effects, sometimes quite dramatic ones. Note that some Volkswagen diesel controls allowed engines in the 2015 scandal to emit 40X the allowable emissions due to ECM program overrides.

The ECM also interacts with braking and stability systems, airbag controls and other safety features. It records important data. In the case of an accident, an investigator can read the data from the past three hard braking incidents from the record.

Fuel Economy Improvement

The Cummins ECM optimizes engine fuel economy through control of the engine's idle speed, maximum RPM, and maximum road speeds.

In a 2015 publication of the National Highway Traffic Safety Administration, these three factors had the most effect on fuel consumption for a wide range of engines, loads and conditions.

According to Cummins Engines "Secrets of Better Fuel Economy" there are certain "rock-solid rules."

  • Above 55 mph, each 1 mph increase in vehicle speed decreases fuel economy by 0.1 mpg.
  • Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel efficiency by 1%
  • The most efficient drivers get about 30% better fuel economy than the least efficient drivers.

An ECM programmed to limit trucks to a maximum speed of 55 mph (speed of most efficient operation) reduces overall fuel consumption.

Improved Engine Performance

An ECM monitors engine temperature, manifold absolute pressure, throttle position and engine speed. With data from these sensors, an ECM adds fuel to the fuel injection line when air flow mass increases. Cold temperatures also need additional fuel for optimum engine performance.

Better responsive performance means better mph. For those looking for more horsepower and torque, ECM remapping can change performance values to prioritize horsepower increases of 30-40 hp. An increase of torque by 80nm is also possible.

Use extreme caution when modifying your programming for more power. High- performance turbocharged diesel engines must NOT have advanced timing. The increased internal pressure risks cracked heads and broken pistons.

Reduced Emissions

An ECM measures the air mass flow rate and calibrates the fuel injection system to the most appropriate air-fuel mixture ration. This ensures that optimum amount of fuel is burnt. The more efficient the burn, the less residue emitted.

This assumes that your engine is mechanically sound. Most gross pollution comes from poorly maintained air filters and leaky seals. Governor tampering and tampering with transient air-fuel ratio control devices is another common culprit in excessive emissions.

Use caution when remapping an ECM. Faulty software can result in inaccurate data and excessive emissions. (See Volkswagen scandal)

Cummins ECM Fine-Tuning

Engineers spend hundreds of hours balancing fuel economy with power and emissions standards. They cannot control every input. Their priorities may or may not align with your engine needs and priorities.

Any engine can output more power or run leaner on fuel. An updated Cummins ECM is meant to keep your engine at peak performance. Fine-tuning your ECM requires an expert with special tools and calibration.

Your technician may reprogram your ECM, block or change your sensor inputs or outputs for the desired effects. Be aware that tuning your ECM voids the warranty on many engines.

You could buy pre-set engine performance maps, but they can shorten the life of certain components and complicate repairs in the future. Incomplete programs or programs that ignore certain inputs could result in higher emissions, premature engine wear or dangerous driving conditions.

Troubleshooting Your ECM

Your ECM keeps your vehicle running at peak performance. Keep your ECM at peak performance too. Protect it from excessive vibrations, heat or cold. Corrosion on metal parts or connections can cause critical errors.

Regular maintenance of your ECM, with manufacturer software updates and a physical check of the ECM and sensors is good practice. Contact with water, shorts in the sensors or clogged lines make all the difference in data accuracy.

Faulty data, not a faulty ECM is the source of most trouble. Some sensors require regular replacement, but an engine computer module is rarely replaced for failure. The most stable ECM can fail, however, so here are a few tips to help you decide if it is time to repair or replace.

ECM Faults- Common Culprits

Blame for ECM faults most commonly falls on the sensors that provide input to the computer module. Other times, faulty wiring, a voltage issue or power relay problem are the trigger for cascading errors. Computer memory errors are also common.

Typical parts replacement to solve ongoing errors includes ignition modules, idle control plugs, fuel injectors or spark plugs. Check and replace the power supply if necessary to return the ECM to top condition.

If your ECM is an older model, brittle plastic insulation could be to blame.

Diagnostic Trouble Codes

Your ECM logs fault codes (diagnostic trouble codes) to help pinpoint problems. Some common signs of trouble:

Check Engine Light

Any fault in the sensors or circuitry and your ECM illuminates this amber dashboard light. There are several reasons this could happen. Some require immediate attention, some can take a little more time.

It could be your battery, your air intake or even your alarm system triggering your ECM. Diagnose your Cummins ECM at this stage is by going through the trouble codes log.

Engine Underperformance

Engine underperformance is a telltale sign of a faulty ECM or software program. Fuel injection timing or the air-fuel ratio are thrown off by inaccurate data or poor processing. This reduces engine efficiency, horsepower, and torque.

Misfiring or Stalling

If you have eliminated sensor fault and verified the mechanical fitness of the system and still have misfires and stalls, this indicates a faulty ECM. Erratic mistimed fuel injection indicates possible ECM failure.

Engine Won't Start

If the required engine inputs are not present, the ECM will not allow the engine to start. Complete chip failure will not allow an engine to start either. The engine will crank and it will be mechanically sound, but it will not start or run.

Surging Idle

Erratic bucking and surging, sudden multiple sensor fail can all be signs of an imminent ECM failure. It is rare, but if the whole engine computer module fails, you need to replace the chipset.

Repair or Replace Entire Cummins ECM

The high-quality Cummins ECM is regularly updated and supported. Brand new and refurbished units can be easily installed keep your engine at its peak. After-market tweaks for responsiveness and efficiency are common.

An ECM is a just a specialized circuit board. If the problem is caused by a loose connection, dust or a real, actual bug, the ECM itself can be repaired. Given that the cost of a new Cummins ECM can reach $1800 with replacement board and programming, a $400 repair and resealing is a good option.

Water contaminated circuits and wiring cannot be reliably repaired. In that case, a new or refurbished unit is the only choice. The unit alone can be around $1000 with another $500 or so needed for programming.

Restoring your Cummins ECM

The process itself is time-consuming. Your technician will record your vehicle's vital statistics like year, model, make, VIN and other data into a computer. Then the computer will go through an identification procedure to learn the particular needs of your vehicle configuration.

Anti-theft devices, custom engine modifications and other deviations from the standard showroom configuration also need to be integrated into the installation. The process can take a few hours of technician time.

Next Steps for Better Engine Performance

Get your engine into tiptop mechanical order before starting with your ECM. Regular upgrades, performance fuel injectors, and fuel system upgrades do not need circuit board adjustments to improve performance.

Exhaust system upgrades such as better quality mufflers, particulate filters, and wider exhaust pipes also make a difference, again without changing your factory presets.

Once your mechanical fixes are complete, you can start working with your ECM technician to adjust factory presets with you. Your fuel quality, load, terrain and other factors determine some of the changes you may want to the software.

Choose Your Technician Carefully

Only allow a qualified, experienced shop with the right equipment to change your programming. Many "bootleg" files are harmful to the life of our engine and can cause piston failure. Aftermarket chips and files may void warranties. Proceed with extreme caution.

That said, your ECM factory presents made assumptions about your driving habits, terrain, load, and priorities. Some or all of these assumptions are incorrect. A good shop can adjust and balance timing tables to give you better fuel economy and power based upon your conditions.

If you want better engine performance, then invest in your Cummins ECM. It is the reliable and intelligent choice for high-performance diesel controls.

Questions and comments? Contact us today.

Posted On: 06/07/2018

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