Removing Emission Monitors: Pcm Reset For Performance

The powertrain control module (PCM) is the brain of your vehicle. It controls the engine, transmission, and other components based on data from various sensors. Resetting the PCM puts your car back to its factory settings, which can be done by disconnecting the car battery or pulling the fuse. This can clear fault codes and resolve issues like a lit check engine light. However, resetting the PCM will not typically clear all learned parameters and adaptive data.

Emission monitors are methods used by the PCM to determine whether an emissions system repair was performed properly. There are continuous and non-continuous emission monitors. Continuous monitors include Misfire Monitoring, Fuel System Monitoring, and Comprehensive Component Monitoring, which run every time you drive your vehicle. Non-continuous monitors, like the EVAP monitor, HEGO monitor, and Catalyst Efficiency monitor, only run under certain driving or operating conditions.

Removing emission monitors from the PCM may involve flashing or tuning the PCM, which can be done using a tune and HP tuners. However, it is important to note that changing the PCM programming may have implications for emissions testing and could be illegal for street-driven vehicles.

Resetting the PCM

Method 1: Disconnecting the Car Battery

This method is straightforward and can be done in a few simple steps:

• Turn off your vehicle and ensure that all electrical components are switched off.
• Open the hood of your vehicle and locate the battery.
• Identify the positive (+) and negative (-) terminals on the battery.
• Disconnect the negative terminal first, using a wrench to loosen the lock nut if necessary.
• Wait for a period of 10 to 15 minutes.
• Reconnect the battery terminals, starting with the positive terminal first.

Method 2: Removing the ECM Fuse

This method involves resetting the Engine Control Module (ECM), which is essentially the brain of your vehicle, by removing its fuse:

• Ensure that your vehicle is completely turned off.
• Locate the fuse box, which is usually in the engine compartment, and open the cover.
• Find the ECM fuse on the fuse diagram. It may be labelled as "ECU" or "ECM".
• Carefully remove the ECM fuse. Make sure that the ignition key is off before removing the fuse.
• Wait for at least 10 to 15 minutes.
• Reinsert the ECM fuse into its original position.
• Close the fuse box cover.

Method 3: PCM Reset through the Fuse Box

This method is specific to Ford vehicles and is a quick and easy way to reset the PCM:

• Open the hood of your Ford vehicle.
• Locate the fuse box in the engine compartment. It usually has a casing that displays the fuses and their amperage.
• Remove the lid of the fuse box by placing your finger on the notch and carefully lifting it.
• Find the fuses named "ECU" and "BACKUP" and pull them out. Ensure that the ignition is off before removing the fuses.
• Wait for at least 10 minutes before returning the fuses to their exact original positions.
• Replace the lid of the fuse box.
• Drive your vehicle for a few miles to clear any error codes or warning lights that may still be present.

Method 4: Using a Diagnostic Tool

You can use a diagnostic tool, such as an OBD II scanner, to reset the PCM and clear any error codes:

• Connect the OBD II cable to the OBD port, usually located under the steering column.
• Insert the ignition key and turn it to the "on" position without starting the engine. The dashboard lights should illuminate.
• Turn off any car accessories, such as the air conditioning or radio.
• Press the "erase" button on the scanner tool to clear any diagnostic trouble codes.
• Wait until the "no codes" message appears on the scanner, then turn off the ignition.
• Take your vehicle for a test drive. If the warning light remains on, the issue may not be resolved, and further diagnosis is needed.

Method 5: PCM Reset through the Battery

This method is more complex and involves disconnecting the battery to reset the PCM:

• Open the hood of your vehicle.
• Use a deep socket wrench to disconnect the negative cable from the battery's negative terminal.
• Place the disconnected cable on an insulator, such as cardboard or a rag, to prevent it from touching the battery or any metallic objects.
• Connect one end of a jumper cable to the disconnected negative cable and the other end to the connected positive cable. Leave it connected for about 10 to 15 minutes. This helps drain any remaining charge from the ECU capacitor.
• Disconnect the jumper cable from the battery cables.
• Reconnect the negative cable to the negative terminal and ensure it is tight.
• Insert the key into the ignition and turn it to the "on" position without starting the engine. Leave it in this position for 10 seconds, then turn it off. Repeat this step.
• Start the engine and let it idle for about 5 minutes. This allows the PCM to relearn the idling values. Keep all accessories turned off during this process.
• Take your vehicle for a test drive, shifting through the gears. This helps the PCM relearn the shift points and fuel trims. All error codes and warning lights should now be cleared.

It is important to note that resetting the PCM may not always be the best solution and can sometimes result in complications. Before performing a reset, it is recommended to consult a professional mechanic or weigh your options to determine if it is the most appropriate course of action.

Drive Cycle and Emissions Readiness Monitors

When a vehicle has an emissions system problem, it usually triggers a Check Engine or Service Engine Soon Light. This indicates that an emission system problem and fault code have been recorded in the PCM. The fault code must then be accurately diagnosed and repaired. After the repair is completed and the fault code is cleared, the PCM will run a series of self-tests to determine whether the repair fixed the problem and if the emissions systems are functioning properly. If they are, the vehicle can now properly reduce the emissions released into the atmosphere from its operation.

This process was designed to prevent a vehicle from passing an emissions test with a known problem. Before 1996, it was common to turn off the Check Engine Light by clearing the code just before an emissions test, without performing the necessary repair. The Drive Cycle and Emissions Readiness Monitors have largely stopped this unethical practice.

A Drive Cycle duplicates the conditions of a person going out and driving their vehicle after it has been sitting overnight. First, the driver cold-starts their engine and lets it warm up while they fasten their seat belt, select a radio station, adjust the volume, and let the windows defrost. The car is then driven through city streets at speeds of 25 to 35 mph. Next, the car enters the freeway and accelerates briskly to match the speed of other drivers as they merge with freeway traffic. The vehicle is then driven at a steady speed of between 55 and 60 mph for at least four to five miles. After this, the vehicle exits the freeway and is driven through city streets again before pulling into a parking spot where the engine idles for 20 to 30 seconds before being turned off. On many vehicles, one of these Drive Cycles is sufficient to set all or most of the Readiness Monitors. Other vehicles require that this process be repeated on two or more successive days.

There are two types of readiness monitors: continuous and non-continuous. Continuous monitors are constantly tested and evaluated while the engine is running. Non-continuous monitors need certain conditions to be met before a test can be completed. Conditions necessary to run the non-continuous self-diagnostic tests vary. Some monitors require that the car follows a predefined drive cycle routine. Some require two drive cycles because of the need for a cool-down and warm-up periods between. Each emission monitor can have different requirements for the conditions.

To prepare your vehicle for a basic Drive Cycle, ensure the fuel tank is between 30 and 70 percent full. Some systems, like the EVAP system, need a specific level of fuel for the tests to be trusted. The vehicle must also have a good alternator and a strong battery. The vehicle must sit overnight, or for at least eight hours, in an environment that is less than 90° F. The engine temperature needs to match the air temperature to establish an accurate baseline for the testing. The keys must be out of the ignition and all of the doors must be closed while the vehicle sits overnight because many of the onboard computers "boot up" when the keys are in the ignition.

• Start the vehicle and let it idle for two to three minutes in Park or Neutral. While it is idling, turn on the headlights, heater/defroster, and rear defroster for a three to five minute warm-up phase. Let the idle speed settle down to near the normal speed.
• Put the vehicle in gear and drive through city streets at about 25 mph. Go up to about 35 to 40 mph a few times before slowing down to stop. Accelerate from each stop in a normal fashion.
• After the vehicle has been cold-started and driven for a few miles on city streets, the next step is to take it on a short freeway trip. Enter the freeway and accelerate to match the speed of other drivers as you merge with freeway traffic. When you have accelerated up to around 60 mph, stay in the slow lane and maintain a steady speed of 55 to 60 mph for a minimum of five miles.
• As you exit the freeway, take your foot off the accelerator and let the vehicle coast down until it stops under its own power. Do not use the foot brake and do not shift gears until the end of this "coast down" phase.
• After you have completed the freeway trip, drive through the city streets again. Go up to about 35 to 40 mph a few times and then maintain a city speed of 25 mph before slowing down to stop. Again, don't roll through the stop and make sure to accelerate normally.
• Pull into a parking place and let the engine idle for one to two minutes and then shut it off.
• Drive your vehicle to your regular shop and have them re-check your readiness monitors, present codes, and pending codes.

Faulty battery

A faulty battery can cause a host of issues with your car, and it's important to know when to replace it. Here are some signs that your battery is faulty or dying:

• Corrosion on the Connectors: Check for a blue-green powder or crystal-like substance on the positive and negative caps of the battery terminals. This indicates leaking battery acid and is a sign that the battery needs to be replaced immediately.
• Warped Battery Case: Look for swelling, cracking, or a bulge on the battery case, which is typically rectangular. Oddly shaped cases may indicate a serious issue.
• Rotten-Egg Smell: A leaking battery releases hydrogen sulfide gas, which smells like rotten eggs, sewers, or well water.
• Electrical Issues: If your car experiences sudden electrical issues, such as dim headlights, flickering dashboard lights, or malfunctioning electronic windows and sunroofs, it could be due to a faulty battery.
• Clicking When Turning the Key: If you hear a clicking sound when trying to start your car, it could be due to a faulty battery, a bad starter, or a bad alternator.
• Slow-Starting Engine: If your engine takes a long time to crank or turn over, it could be a sign that your battery is not providing enough energy.
• Frequent Jump-Starts: If you need to jump-start your car frequently, it's a sign that your battery is failing and may need to be replaced, especially if it's over three years old.
• Check-Engine Light: While the check engine light can indicate various issues, it could also be a sign of a faulty battery, especially when combined with other symptoms.

To determine if your battery is faulty, you can perform a few simple tests:

• Inspect the Battery: Look for any physical damage, such as a bulge or crack in the case, or loose or broken terminals.
• Take a Voltage Reading: Check the voltage of the battery. A fully charged battery with a voltage of 12.4 or less could indicate sulfation, a common issue with lead-acid batteries.
• Load Test the Battery: Use a digital voltmeter to test the battery under load. For accurate results, ensure the battery is fully charged and left to sit for 12 hours before testing.

If you suspect that your battery is faulty, it's important to consult a professional mechanic or automotive shop for further diagnosis and replacement if necessary.

Clearing fault codes

The powertrain control module (PCM) is the brain of your vehicle. It controls your ride's powertrain and manages your engine, transmission, and other related components based on the data sent by various sensors. When your vehicle has an emissions system problem, it almost always triggers a Check Engine or Service Engine Soon Light. This signals that an emission system problem and fault code has been recorded in the PCM. The problem indicated by the fault code must now be accurately diagnosed and repaired.

After the proper repair has been completed and the fault code cleared, the PCM will run a series of self-tests to determine whether or not the repair actually corrected the problem and if the various emissions systems are running properly. If they are, they can now properly minimize the emissions released into the atmosphere from the vehicle's operation.

This process was designed to prevent a vehicle from slipping through an emissions test with a known problem. Until 1996, a common tactic was to turn off the Check Engine Light by clearing the code just before an emissions test, without performing the proper repair. The Drive Cycle and Emissions Readiness Monitors have, for the most part, stopped this unethical tactic.

The Drive Cycle and Emissions Readiness Monitors are methods used by the PCM to determine whether an emissions system repair was properly performed. A Drive Cycle is a special test drive that duplicates the scenario of a person starting her car and making a short freeway trip, as if she were driving to work. While the Drive Cycle test is going, the engine computer runs little tests or "readiness monitors" to see if the emissions system is working properly.

There are several reasons why the monitors may be incomplete. If your car has recently been repaired for a problem that set a Diagnostic Trouble Code (DTC) (check engine on) and the technician cleared the DTC, he also erased the monitors. Also, if the battery has been disconnected, replaced or needed a jump-start, the monitors may be erased.

To clear fault codes, you can reset the PCM. Resetting the PCM puts your car back to its factory settings. There are two ways to reset the PCM. The first method is by disconnecting the car battery, while the second way is by pulling the fuse.

The exact steps for the first method depend on the vehicle, but here’s how it’s typically done:

• Open the hood and look for the car battery.
• Remove the negative battery cable.
• Wait for around five minutes.
• Turn the headlights on with the battery disconnected to empty the power in the capacitors.
• Put the terminal back on again.

The tricky part of the second method lies in locating the fuse box. You can consult your manual to determine its exact location. Then, you can reset the PCM by pulling the fuse, which typically involves these steps:

• Find the fuse for your PCM. If you’re unsure of which fuse to remove, consult the fuse box diagram in the owner’s manual or consult online resources.
• Remove the fuse from the box.
• Put it back on after 10 to 20 seconds.

PCM replacement

The power control module (PCM) is the "brain" of your car. It monitors over 100 functions, from automatic transmission to O2 sensors and engine pressure. PCMs are rated to last a long time, so their failure is usually caused by other issues in the car's electrical system, such as power surges.

If your PCM is failing, it's a good idea to replace it as soon as possible. PCM problems will only get worse and can cause your car to shut down while driving. The average cost of a PCM replacement is between $885 and $966, although dealership prices can be as high as $1,600 in parts and labour.

• Loosen the PCM harness connector bolts from the centre of the PCM harness connectors.
• Remove the PCM harness connectors from the PCM.
• Remove the PCM retaining bolts and nuts.
• Slide the PCM away from the intake manifold past the mounting studs and remove it from the vehicle.
• Remove the PCM mounting studs from the intake manifold only if replacing them.
• Install the new PCM mounting studs to the intake manifold, if necessary, and tighten them.
• Install the new PCM onto the studs.
• Install the PCM retaining bolts and tighten them.
• Install the PCM retaining nuts and tighten them.
• Install the PCM harness connectors to the PCM body.
• Tighten the PCM harness connector retaining bolts.
• If a new PCM is being installed, it must be programmed.

It is important to note that the ignition must be off when disconnecting or reconnecting power to the PCM to prevent internal damage. Additionally, any debris on the PCM connector surfaces should be removed before servicing, and the PCM module connector gaskets should be inspected to ensure they are installed correctly.

In some cases, it may be possible to reprogram the PCM instead of replacing it. However, this should only be done by a qualified technician as incorrectly tweaking the settings could lead to crashes and liability issues.

Finally, it is worth mentioning that the PCM is responsible for emission monitors, which are methods used to determine whether an emissions system repair was properly performed. These monitors run self-tests to ensure that repairs have been made correctly and that the emissions systems are functioning properly.

Frequently asked questions