Encountering OBD2 codes P0171 and P0174 on your 1998 Ford Explorer can be frustrating. These codes, indicating “System Too Lean (Bank 1)” and “System Too Lean (Bank 2)” respectively, often point to issues that can impact your vehicle’s performance and fuel efficiency. If you’re experiencing these diagnostic trouble codes, you’re likely seeking to understand the root cause and find effective solutions. This guide will walk you through a common culprit behind these lean codes in 1998 Ford Explorers and provide a repair approach based on real-world experience.
The P0171 and P0174 codes are triggered when your Ford Explorer’s engine computer detects an excessively lean air-fuel mixture in both engine banks. This means there’s too much air and not enough fuel in the combustion process. While various factors can lead to a lean condition, one frequent cause, particularly in older vehicles like the 1998 Ford Explorer, is vacuum leaks. Unmetered air entering the engine after the Mass Air Flow (MAF) sensor can disrupt the intended air-fuel ratio, leading to these lean codes.
Initial troubleshooting steps often involve inspecting easily accessible components. Checking the MAF sensor by cleaning it can sometimes resolve issues if it’s simply dirty and misreading airflow. Similarly, a thorough inspection of the air intake duct for cracks or loose connections is crucial to ensure all air entering the engine is properly measured by the MAF sensor. However, if these preliminary checks don’t clear the codes, a more in-depth investigation might be necessary.
For 1998 Ford Explorers, and similar models like the 1997 Explorer, a common area for vacuum leaks is the intake manifold, specifically where the plastic intake manifold mates to the fuel injector log. Over time, the gaskets in this area can degrade, leading to air leaks that trigger the P0171 and P0174 codes. Addressing this issue often requires removing the upper intake manifold to access and replace the affected gaskets.
The repair process involves removing the plastic intake manifold to access the gaskets that seal the fuel injectors and the manifold itself. Replacing these gaskets can effectively seal vacuum leaks and resolve the lean condition. To undertake this repair, you will need to procure specific gaskets. Based on experience with a similar model year, the following parts have been found necessary:
- F57Z-9E436-AA (QTY 3) – Intake Manifold Gaskets
- F6TZ-9E436-C (QTY 1) – Intake Manifold Gasket
- 95TZ-9E936AA (QTY 1) – Throttle Body Gasket
- 957Z-9F670-AA (QTY 1) – Air Intake Plenum Gasket
- FOPZ-9229-A (QTY 2 packs of 10, you’ll need 12) – Fuel Injector O-rings
- E6AZ-9D476-B (QTY 1) – PCV Valve Grommet
When performing this repair, consider obtaining an O-ring for the EGR (Exhaust Gas Recirculation) tube where it connects to the plastic air intake manifold. Disconnecting the EGR tube from the intake manifold can be a challenging step. A helpful tip is to unbolt the EGR tube from the EGR valve itself and remove the intake manifold with the EGR tube still attached. This allows for easier separation of the tube from the intake manifold once it’s on a workbench. The EGR tube is held in place by an O-ring which can also be a source of leaks or become damaged during removal.
In conclusion, if you are facing P0171 and P0174 OBD2 codes on your 1998 Ford Explorer after initial checks of the MAF sensor and intake duct, consider the intake manifold gaskets as a potential culprit. Replacing these gaskets, along with the fuel injector O-rings and potentially the EGR tube O-ring, can address vacuum leaks and resolve the lean condition causing these codes. This repair, while requiring some mechanical skill, can be a cost-effective solution to restore your Ford Explorer’s performance and fuel efficiency. Remember to always consult a repair manual specific to your vehicle and take necessary safety precautions when working on your car.
