Ameer Randolph
The 1988 318 was the first year of the throttle-body fuel injection system, which was used in Dodge trucks. The system features dual throttle body injectors, with one injector for each cylinder. However, issues with the throttle body and/or fuel injectors have been reported by some owners. Problems range from injectors stopping up to trucks stalling and hesitating.
| Characteristics | Values |
|---|---|
| Year | 1988 |
| Model | W100 |
| Brand | Dodge |
| Engine | 318 |
| Fuel System | Fuel-injected throttle body |
| Fuel Injector Type | Low impedance |
| Number of Fuel Injectors | 2 |
| Fuel Pump | In-tank |
| Fuel Pump Replacement Cost | $73.99 |
| Fuel Injector Pressure Regulator Cost | $52.99 |
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What You'll Learn
- Fuel injectors spray alternately with a dual plane intake manifold
- The throttle body injection circuitry was designed for low impedance injectors
- A noid light will indicate if the injectors are working
- The 1988 318 fuel injection system was changed in 1989
- The 318 engine has an injector for each cylinder
Fuel injectors spray alternately with a dual plane intake manifold
The 1988 318 fuel injection system was the first of its kind and was changed in 1989. It is a good system if maintained well. The TBI 318 was rated at 146 HP, while the 2.2L intercooled Turbo's of those years made more horsepower (174) and almost as much torque (200).
The 1988 318 has throttle body fuel injectors, and these spray alternately with a dual-plane intake manifold. The injectors are energised alternately, and a noid light will indicate whether they are working. The light attaches to the electrical connectors and lights up when the circuit is complete or the injectors are grounded.
A dual-plane intake manifold is used with a carburettor due to better air/fuel distribution. With EFI, you only need to transport air to the cylinder through the manifold, so a single plane is preferable. A dual-plane intake manifold is not ideal as you cannot trim individual injectors.
The fuel injectors will be fitted side by side, at a 45-degree angle on the manifold, firing directly towards the ports. This is a conventional firing pattern of 1-3-4-2. The injectors are placed about 25-30mm from the face of the head casting.
To replace a fuel injector, first, rotate the cap and injector to align the attachment hole, then press down on the cap to ensure a proper seal. Next, install the torx screw and connect the battery ground cable. Finally, pressurise the system and check for leaks before reinstalling the air cleaner.
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The throttle body injection circuitry was designed for low impedance injectors
The throttle body injection (TBI) 318 was introduced in 1988 and was rated at 146 HP. The TBI circuitry was designed for low impedance injectors, which have a coil resistance of 2-4 ohms. Low impedance injectors are typically used in high-performance applications or large-sized injectors, where a large amount of fuel is needed. They are also known as peak-and-hold injectors because they use a high current to open the injector and then reduce the current to keep it open during the pulse width. This type of injector is more complex and expensive than high impedance injectors.
High impedance injectors, on the other hand, have a coil resistance of 8-16 ohms and are widely used in street applications. They are also known as saturated injectors because they use a high resistance value of around 12 ohms across their coil and run at low current levels to keep the circuitry cool. While high impedance injectors are typically used in production vehicles, low impedance injectors are more common in aftermarket ECUs and race applications.
It is important to note that the choice between low and high impedance injectors depends on the specific application and the ECU of the vehicle. While some ECUs can handle both types of injectors, it is generally recommended to stick with the type of injector that the vehicle came with. In the case of the 1988 318, it appears that the TBI circuitry was designed for low impedance injectors.
Over time, the gap between low and high impedance injectors has become smaller due to the growing popularity and advancements in high impedance injector technology. Today, high impedance injectors can outperform older low impedance injectors at larger flow rates due to their newer designs, tighter manufacturing tolerances, and lighter moving parts. However, there are still many vehicles equipped with low impedance injectors that provide great drivability and performance.
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A noid light will indicate if the injectors are working
The 1988 W100 is a Dodge vehicle with a 318 engine and throttle body fuel injectors. It is important to be able to identify whether the fuel injectors are working properly, as this can cause issues with the vehicle's performance.
A noid light is a tool that can be used to test whether a fuel injector is receiving power and pulse signals from the fuel injection computer. The noid light attaches to the top of the electrical connectors and lights up when the circuit is completed or the injectors are grounded. This test can be carried out on most vehicles, although different makes and models have different types of connectors, so it is important to select the correct noid light.
To use the noid light, first disconnect the fuel injector from its electrical connector. Then, attach the noid light to the connector. Step away to a safe distance and ask another person to crank the engine. If the engine is cranking, the noid light should be flashing on and off. If the noid light is flashing, this indicates that the fuel injector is receiving power and pulse signals. If the noid light is not flashing, this indicates that electrical power is not reaching the fuel injector, and the fuel injection computer may not be delivering the pulse signals.
In the case of the 1988 W100, issues with the throttle body and/or fuel injectors have been reported, with one owner reporting that one of their fuel injectors was not working and needed to be replaced.
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The 1988 318 fuel injection system was changed in 1989
The 1988 318 fuel injection system features dual throttle body injectors, which are ground-side switched by the PCM (powertrain control module). The crankshaft must be turning for the PCM to close the ASD load-side contacts and provide power to the fuel injectors. The throttle body injectors used in the 1988 model are fatter than those used in later models, and they have higher impedance. This means they require more electrical current to operate.
The 1988 318 fuel injection system was prone to issues. Some common problems include vacuum hoses being incorrectly hooked up, a faulty throttle body temperature sensor, and a faulty coolant temperature sensor. The fuel injectors themselves could also become blocked, as seen in the case of one owner whose left-side injector stopped delivering fuel.
The 1989 change to the 360 TBI system addressed some of these issues. The new system featured lower impedance injectors, which reduced the overall electrical power consumption necessary to operate the fuel injectors. This change marked a shift from throttle body injection to port injection, with the presence of 4, 6, or 8 injectors.
The 1988 318 fuel injection system could be upgraded to a multiport fuel injection (MPFI) system, which offered a boost in power and smoothness. However, this upgrade was not a simple process and required changes to the fuel pump, fuel lines, and other components.
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The 318 engine has an injector for each cylinder
The MFI system uses a wiring harness that connects to all the fuel injectors, which is a simpler setup than the carburetor-like throttle body of the TBI system. The MFI system also operates at a much higher fuel pressure than the TBI system. The TBI system operates at around 7 psi, while the MFI system operates at around 45 psi.
Upgrading from a TBI to an MFI system can be a complex process. It may require a new fuel pump, fuel lines, and an updated transmission controller. It is also important to ensure that the injectors are the correct size and are compatible with the throttle body.
The 318 engine with the TBI system has been known to have some issues. Some common problems include faulty vacuum hoses, a bad throttle body temperature sensor, and a faulty coolant temperature sensor. It is important to regularly maintain and service the fuel injection system to ensure optimal performance and fuel economy.
Overall, the 318 engine with an injector for each cylinder offers improved performance and fuel efficiency over the TBI system. However, it is important to carefully consider the complexity of the upgrade process and the potential costs involved. Regular maintenance and servicing of the fuel injection system are crucial for keeping the engine running smoothly.
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Frequently asked questions
A 1988 318 has two fuel injectors.
Some common issues with the fuel injectors of a 1988 318 include incorrect hookups of vacuum hoses, a faulty throttle body temperature sensor, and a faulty coolant temperature sensor.
Some troubleshooting tips for the fuel injectors of a 1988 318 include performing a wet and dry compression test of each cylinder, checking the injector flow, and verifying the proper functioning of the throttle position sensor.
Some options for upgrading the fuel injectors of a 1988 318 include converting to a multiport fuel injection system or replacing the entire engine with a newer model that has improved fuel injection.
