Ford F-250/F-350: Why is My Truck Losing Power?

Is your truck suffering from loss of power and acting sluggish as a result? Learn about the different factors that can cause this and how to address them.

By Piyush Kayastha - December 22, 2014

This article applies to the Ford F-250 and F-350 (2005-2014).

Every motor is comprised of several components, all of which work in tandem to synchronize how well a vehicle performs. Over time, all of these components wear and require replacement or service. Your vehicle will show signs to indicate that it's not running at its best. It's important to take a thorough measure of these symptoms to determine the source of the problem(s) and address them accordingly. Depending on whether your truck is gas or diesel, the procedures vary slightly.

Materials Needed

  • OBD2 reader
  • Flat head screw driver
  • T-20 Torx bit
  • Torque wrench
  • Compression test kit
  • Air filter
  • CRC MAF cleaner
  • PCV valve
  • Oil pan gasket
  • Head gasket

Gas Vehicles

Step 1 - Check trouble codes

The truck's on board ECU (computer) can tell you what problems are being recorded, especially if they are related to emissions or misfires.

  • Use an OBD scanner to scan the codes.
  • Alternatively, some auto supply stores scan vehicle codes for free.
Figure 1. Connect the scanner in the port located under the dashboard.

Step 2 - Check air filter

Air filters play a crucial part in how your car performs and are directly related to gas mileage and torque. These components are subject to wear and can often get dirty. When they get really dirty, they get clogged, thus preventing the air to flow easily into the engine, which results in a sluggish feel.

  • Remove surrounding plastic to expose air filter.
  • Inspect filter for debris and dirt.
  • Replace if necessary.
Figure 2. Inspect and replace the air filter.

Pro Tip

There are "reusable" versions of air filters which can go a long way in terms of maintenance.

(Related Article: How to Replace Your Air Filter - Ford-trucks.com)

Step 3 - Clean MAF sensor

The Mass Air Flow (MAF) sensor is responsible for detecting the incoming air and temperature to give the vehicle's ECU a proper reading of how much air is being "sucked" in for combustion. If this sensor is blocked or suffering from carbon and dirt build up, these readings can be off, and there will be a sluggish response at the throttle.

  • Using a flat head screw driver, pry the release tab and unplug the sensor (Figure 4).
  • Using the T20 Torx bit, undo the screw on top and bottom right of the sensor (Figure 5).
  • Remove the sensor, spray with MAF cleaner gently, and let dry for 15 seconds (Figure 6).
  • Figure 3. MAF sensor location.
  • Figure 4. Unplug the sensor.
  • Figure 5. Undo the screws.
  • Figure 6. Spray sensor with cleaner.

Warning

DO NOT touch electrical contacts to MAF sensor with anything. It is a sensitive electrical component.

Step 4 - Examine head gasket for leaks

If there is a leak at the head gasket, it is possible the motor is losing compression and causing the throttle to feel sluggish with overall loss of power. It is also common for the PCV valve and related tubing to be the source of a leak, which should also be inspected and replaced if necessary.

  • Lie on the floor with a flashlight and inspect the under carriage of the truck.
  • Determine if there is an oil leak coming down from the sides of the motor's head or the oil pan (Figures 7 and 8).
  • Figure 7. Oil leaking into pan.
  • Figure 8. Oil leaking down the sides.

Pro Tip

Sometimes you can see oil running down the side of the transmission torque converter. This is a clear indicator that there is a head gasket leak. Other times, it has been known for the PCV valve to have been the source of the problem. It is easily found on the valve cover between the fuel rail and battery, and can be swapped out for a new one.

Step 5 - Check for dragging brakes

Brakes are a wear item and are certainly prone to needing regular service and/or replacement. The situation with dragging brakes can elude to a "stuck" caliper or improper brake bleeding. Whenever brakes are serviced, it is always recommended to bleed the system for trapped air and to free up any lines that may have gotten "kinked" in the process.

  • Jack up the front of the truck and spin front wheels independently.
  • Observe if a caliper is visibly stuck and replace if necessary.
  • Repeat this process for rear of the truck.
  • Check brake fluid level and bleed the system to clear the system of any trapped air or kinks in the lines.
Figure 9. Bleeding brakes.

Pro Tip

Often, the slide pins to calipers can be the culprit to a "stuck caliper." Replacing these can free the caliper up during service.

(Related Article: How to Replace Your Brake Fluid - Ford-trucks.com)

Step 6 - Perform compression test

Misfires are common reasons why a vehicle's performance and gas mileage can suffer. Determining the sources of misfires can be found by running a compression test in each cylinder using a cylinder compression kit.

  • Remove 20A fuse for fuel pump (refer to owner's manual for your truck's specific year).
  • Remove spark plug from Cylinder 1.
  • Thread tester into the first hole and connect the compression tester gauge.
  • Crank motor for 5 revolutions and record your readings.
  • Repeat for remaining cylinders.
  • Figure 10. Remove the 20A fuse.
  • Figure 11. Typical cylinder compression kit.

Pro Tip

The cylinder(s) with the least compression could be the source of the misfire. If compression is linear across the cylinders, you may need to investigate coil packs, fuel injectors, the alternator, or the starter.

Diesel Vehicles

Step 1 - Check trouble codes

Use an OBD2 Tester or get the vehicle scanned for codes at your local auto supply store. This will be a good way to determine if the on-board ECU has recorded inconsistencies in the motor's optimal operation.

Figure 12. Use an OBD2 Tester to scan the codes.

Step 2 - DPF regeneration or clogged DPF

Diesel particulates in the exhaust are trapped by the Diesel Particulate Filter (DPF). Regeneration is the method by which exhaust temperatures are increased so the particulates are expelled. This can be a major source of loss of power and fuel economy. However, this is a process built into Ford trucks that runs to rid the extra particles in the exhaust system, and is an emission related recycling process. It can occur almost anytime between 100 and 600 miles of driving the truck. This is not something that requires repair. However, the filter will likely need to be changed around 120k miles.

Figure 13. DPF stages.

Step 3 - Check boost pressure lines for leaks

The intake, intercooler, bypass, blow-off, vacuum manifold, and the fuel rail all see boost. They are areas that should be tested for boost leaks. These components are connected via tubes and rubber hoses. Over time, they can become brittle and break or contain tears that will let air escape. These breaks can be audible. The featured video below demonstrates other ways to determine the source of a boost leak or a vacuum leak.

Featured Video: How to Find a Vacuum Leak

Step 4 - Fuel filter / EGR system

Fuel filters are considered wear items and should be replaced per dealer recommendation. However, EGR (Exhaust Gas Recirculation) systems have reportedly shown failure without warning or trouble codes and while all other components are in good shape or recently replaced. When this system has proved to be faulty, the engine will sputter and display a rough idle. This failure is not common on these trucks.

Figure 12. EGR valve location.

Featured Video: Why is My Truck Losing Power?

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