What is an Injector Driver Module?

The collaborative efforts of Caterpillar and International introduced electronic fuel injection to the 7.3 Power Stroke. This engine relies on extremely high oil pressure to build fuel pressure within the fuel injector.

The 7.3 is a direct-injection fuel injection where the fuel is injected directly into the extreme pressures of the cylinder, thus the reason for the high fuel pressure to overcome these pressures.

The 7.3 Power Stroke uses a PCM (powertrain control module) in conjunction with the IDM (injector driver module) to operate the engine. The primary function of the IDM is to boost the DC (direct current) signal sufficiently to operate the fuel injector under such loads. The standard 12 volts would be insufficient in opening the pintle in the injector under these pressures, so the IDM increases the voltage to 115 volts.

The high voltage allows for much faster and accurate opening of the injector. Engine mods are available to further increase this voltage increasing the power and torque by 20 percent or better.

If the voltage drops through resistance in the harness or connector the vehicle will run, but poorly with a severe lack of power. In a failure of the IDM the engine will not start at all.

At this voltage the reaction time is significantly multiplied. The PCM, through various sensors detecting engine speed and load, controls the on and off time of the injectors. A grounding circuit does this for each injector within the computer. Essentially the computer supplies the ground that operates the injectors which has a constant supply of voltage with the key on.

The 6.0 Power stroke system is somewhat different in that it uses a PCM and a FICM (fuel injection control module) both of which are flash programmed. Under this system each injector is operated with the use of an open and a closed driver solenoid.

The PCM is the primary controller in the decision making as to the timing and length of injector pulse, while the FICM is in control of the injector drivers. Both the PCM and the FICM are intrinsically linked through the use of a “CAN.” When replacing either of the units it is necessary to flash them unless purchased from a location claiming to have already done so.

The IDM is located under the fenderwell on the passenger side of the truck. Should any driveability issues arise, access the IDM and check both the harness and the connector. They are prone to failure due to their location. Start the engine and wiggle the wires to the IDM while paying particular attention to engine speed. If the harness or connector is faulty, the engine will respond to the movement of the harness.

As a last word, to prevent problems down the road with a diesel engine, especially a Power Stroke-keep in mind that the injectors operate off oil pressure. The oil pump rests on the top rear of the engine behind the manifold and under the turbo.

It is prone to leaking which reduces the oil pressure and hence lowers the injector performance. A failed oil pump-which is common place-will cause a no start.

Always change the oil at the correct time (mileage) and with the proper grade only. Generally every 2000 miles is appropriate. Diesels will not go as far between oil changes due to engine blow by due to high compression leakage past the rings and valve guide and contaminating the oil. Once contaminated a whole bucket of worms is opened.

What Does A High Pressure Oil Pump Do?

When Ford Motor Company says something is “Built Ford Tough” they mean it, and that’s why a high pressure oil pump is an essential part of the Ford Power Stroke engine. There is an oil pump in every engine, and its job is to circulate the oil throughout the engine. Essentially, it moves through the rotating bearings, the sliding pistons and the camshaft portion of the engine. There are three important functions that the high pressure oil pump has in the Ford Power Stroke engine.

  1. The high pressure oil pump fires at such a high pressure so that the fuel injectors are able to fire. This was introduced on the 1994-1997 line of Ford trucks with Power Stroke engines.
  2. The high pressure oil pump is primarily used as lubricant for the entire engine but it has been found to serve additional purposes in the Ford trucks, including as a hydraulic fluid that helps to run small actuators within the engine as well.
  3. In recent years, the high pressure oil pump has also been used for a variety of other things including: as a tensioner for a timing belt, a tensioner for variators and a tensioner for variable valve timing systems.

The HPOP is a key component in a strong engine designed to help big vehicles have a long lifetime on the road. The high pressure oil pump is known as one of the best parts of the Power Stroke engine, which is built into many different Ford model trucks. It keeps the engine running good and extends the life of the engine by years, and has proven over time to provide a variety of different positive benefits to the truck itself. This is just one reason that Ford has continued to use the pump in its Power Stroke engine.

Replace a 7.3L Fuel Injector

The 7.3L fuel injector is for the fuel injected eight-cylinder diesel engine. The Ford power stroke engine was produced from 1995 to 2002 and typically used in ¾ ton pick-up trucks and heavier. The fuel injectors on a Ford 7.3L diesel engine can be removed individually from the other injectors without having to remove the engines fuel rail.

What you’ll need:

· Engine oil

· Drain pan

· Set of socket wrench’s

· Rotunda injector sleeve brush #104-00934-A

· Injector remover #T94T-9000-AH1

· Injector replacement #T94T-9000-AH2

· Shop towels


1. Place an oil draining pan under each of the oil drains, open plug with a socket wrench, allow the oil to drain and replace the plug. Draining the oil will prevent any oil from getting in the combustion chamber while replacing the fuel injector.

2. Disconnect and remove the valve cover using a socket wrench, unplug the electrical connector from the fuel injector and remove the drain plugs from the oil rail and fuel rail. Remove the retaining screw for the oil deflector and disconnect the oil deflector. Remove the retaining bolt for the fuel injector.

3. Place the fulcrum of injector remover above the cylinder head and below the hold-down plate of the fuel injector. Fasten the remover screw in the hole of the injector plate, tighten the screw to remove the fuel injector from the injector bore and discard the copper washer.

4. Use the Rotunda Injector Sleeve brush to clean the injector bore and remove any debris or sealant residue. Lubricate the new fuel injector with clean engine oil and mount the new copper washer on the injector.

5. Gently push the fuel injector into the injector bore to set the O-rings. Put the open end of the injector replace between the fuel injector and the hold-down plate. Fasten to the cylinder head with the retaining bolt included with the tool kit. Tighten bolt to completely seal the fuel injector and disconnect tool from the cylinder head.

6. Reinstall the oil deflector and tighten the mounting bolt to 108 inch-lbs using a torque wrench. Tight the drain plugs from the fuel rail to 96 inch-lbs and the oil rail drain plug to 53 inch-lbs. Reconnect the wiring harness for the fuel injectors, install the valve cover and replace the oil with new oil.

What is an EGR Cooler?

Exhaust gas recirculation (EGR) coolers are primarily found in diesel engines. Their purpose is to process exhaust gases and lower emissions. They connect the intake manifold to the exhaust manifold and in most vehicles, they are bolted to the side of the engine, usually on the left cylinder head. EGR coolers vary in size and design, depending upon the size of the engine and certain emissions standards.

There are two chambers in the EGR cooler – an outer chamber and an inner chamber. Anti-freeze runs through the outer chamber and the exhaust gases flow through the inner chamber. As they run through the cooler, the anti-freeze cools down the exhaust gases as both are cycled back into the engine. The exhaust gas recirculation cooler can reduce exhaust temperatures up to 1,000 degrees by the time they reach the EGR valve. The most common gas an EGR cooler deals with is Nitrous Oxide (NOx) which forms at high engine temperatures.

When an exhaust gas recirculation cooler fails, the anti-freeze mixes with the exhaust gases and it produces heavy, white smoke that is discharged from the tail pipe. Other signs of a malfunctioning EGR cooler are a check engine light and a failed emissions test.

In addition to automotive engines, exhaust gas recirculation coolers are also using in mining equipment, oil and gas industry pumping equipment and locomotives.

What is an Injector Control Module’s Function?

The injector control module, also known as the injector driver module, is a “stepping stone” between the powertrain control module and the fuel injectors. It is used to prevent a large amount of voltage going through the powertrain control module. The injectors take a lot of voltage — more than a 12-volt battery can put out. The IDM amplifies voltage so that the injectors have enough to fire quickly.

The powertrain control module sends a signal to the injector control module. In turn, the injector control module or injector driver module fires the injectors. This module uses voltage to fire the injectors. If the injector driver module fails, the engine may run poorly, but in most cases, won’t even start. In addition, if a fuel injector fails, it fails to buzz. The rest of the injectors will also fail to buzz to protect the injector driver module.

Injector driver modules may be modified for higher voltage output, faster injection pulsation and longer injector on-time. Because the powertrain control module does not see what the injector driver module is doing, it doesn’t set a code. A stock injector driver module turns the injectors to fully on in 560 millionths of a second. A modified injector driver module could turn the injectors fully on in 440 millionths of a second, depending on the modification.

If the injector driver module is bad and has been properly diagnosed, you can purchase one here and replace it yourself. Replacement steps depend on the year, make and model of your Ford Powerstroke.

What does an EGR Cooler do?

An EGR, or Exhaust Gas Recirculation valve, halts a portion of the exhaust gas from leaving the vehicle through the tailpipe and reintroduces it into the engine removing from it the nitrous oxide to reduce emissions. The trouble with this process is that exhaust is already hot, and it’s being recirculated into a hot engine. An EGR cooler, then, makes this less of a problem by cooling the recirculated exhaust and NOx before reintroducing it to the vehicle’s cylinders and sending the less offensive emissions out of the vehicle.

The cooled and separated gas mixture is said to increase the vehicle’s gas efficiency and lifespan because a cooler engine has to work less hard to keep all of its moving parts mobile. Most car manufacturers do not publish their findings on the tests they conduct to see ho well engines actually perform with an EGR cooler in place. Two camps have formed on the assumptions that a cooler engine performs better and the engine has to work harder to keep the cooler going and therefore the engine performance isn’t better it’s worse.

While that particular argument rages on, engine manufacturers are testing new models of EGR coolers on newer model cars. One specifically designed for diesel engines is hoped to increase diesel engine’s fuel efficiency and keep the diesel engines cooler. Diesel engines have a tendency to run hotter than standard engines, so this would be quite the boon to the trucking industry.

In the meantime, cars and trucks that are required to meet emissions regulations are equipped with the current working models of EGR valves and coolers. They have been proven to, at the very least, reduce emissions effectively, and since that’s what they were designed to do, they will continue to be installed in all present and future models of vehicles until something better comes along to replace it. California happens to be one of the states that has such regulations, and there are steep penalties and fines if your car or truck doesn’t pass annual emissions testing, cooled or not. Since most cars and trucks sold in these states are previously checked for an EGR and its cooler, only the out of state vehicle owners need to worry.

Replace a 6.0L Fuel Injector

6.0L fuel injector can easily get gummed over time, requiring a replacement.

The first step is to remove the fuel injector valve cover and then remove the CAC tube underneath. Additionally, a repairer needs to remove the wiring associated with the glow plug control module as well as the ICP sensor.

The second part is to then remove the standpipe from its position. The pipe could be long or short, depending on the truck engine configuration. The standpipe needs to be separated if it is a long version. Once the oil rail is removed then the long lower part of the standpipe can be put back into place. The oil rail bolts can then be removed and lifted carefully. Watch out for draining oil.

The third step is to position a 19mm socket so that it is secure on the injector connector. With firm pressure, the socket should be pressed in until the injector lock tabs release. The injector connect will then be free to be pulled up. Now the injector hold down clamp can be removed. The parts will come out of the injector bore as they are loosened.

At this point the inside of the injector bore should be examined to see if any of the copper seal or o-rings need replacement. If not, the new injector can be greased with clean engine oil and inserted after the hold down clamp is attached to it. The injector connector o-ring can then be greased and pushed into position until seating with a click. The position should be the same as the other injector connectors.

Next, before the oil rail is reinstalled, a bit of engine oil should be applied to the new injector top. At this point the rest of the parts removed can be reinstalled back in their original sequence. Engine ignition could take a while before the engine turns over after a change due to significant air in the system.

HPOP Purpose

High Performance Oil Pump, or HPOP for short, is required to pump oil in and around Ford Motor Company’s Powerstroke diesel truck engines. It is the only type of pump that can supply enough pressure to get the oil into every area of the engine it needs to go. Without it most Powerstroke engines would be useless and unable to move or function. Combustion engines, running on diesel fuel, need a lot of oil delivered to the pistons so they don’t overheat and lock up. A heavy duty truck engine is always in danger of freezing up if not enough oil is in the engine.

The HPOP not only delivers oil to the engine’s moving parts, but also monitors the pressure it’s using as it delivers the oil. The amount of oil remaining and any necessary refills is monitored too. When the engine light goes on, the HPOP may be reporting a drop in the amount of oil remaining, or it may be reporting something more serious such as the lack of pressure inside the engine. Not enough pressure means not enough lubrication of the entire system, and that’s just plain bad. Oil leaks decrease the pressure too, because there are small holes in the oil delivery system.

What’s worse is an oil pump that can’t deliver the oil fast enough. Air bubbles can form in the oil pump lines and air bubbles in the engine create havoc because there’s really no way to expel the air bubbles from the engine once they are in. Using a 0w oil reduces the need for more power because the oil’s viscosity moves quickly and easily through the engine parts. More traditional oil weights like 5w or 10w are too viscous to move as fast. In these high performance diesel engines, the 0w oil is exactly what you want and need if you expect your truck to keep running.

Ford’s Powerstroke engine isn’t the only diesel engine that takes advantage of HPOPs. Dodge Ram and General Motors each have their own high performance truck with this component tucked into the engine block. Currently no other truck company is in competition or uses a HPOP in their trucks.

Overview of Powerstroke Engine’s HEUI System

Back in the 1990’s, powerstroke engines that you would find in diesel engines needed to be more fuel efficient while still offering powerful engine torque output. In addition, these powerstroke engines had to operate in a more cleaner method to changing air emission standards. So new technology was invented that consisted of the Hydraulically actuated Electronic Unit Injection (HEUI) to address these issues.

What Is A HEUI? A HEUI was created by Caterpillar and International for all powerstroke engines manufactured in the early 1990’s and into the early 2000’s until the injector was replaced by a high pressure common rail system in 2007. The HEUI injector consists of two parts: a high pressure oil chamber and a low pressure fuel chamber. The basic function of the HEUI was to pressurize fuel through the plungers using high pressure oil.

As the fuel pump pushes fuel into the injector, the oil pump places high pressure oil into the injector. The actuator lets the high pressure oil into the injector’s oil chamber to pressurize the intensifier piston. The intensifier piston pressurizes the fuel at a rate (7.1) times higher than the pressurized oil. The powertrain control module (PCM) controls the operation of the HEUI.

Advantages of the HEUI The HEUI had many benefits compared to the mechanical injectors. When at low engine speeds, the engine could produce higher fuel pressure for better fuel economy. Injection timing could be controlled along with the fuel rate through electronic control means. Basically, the HEUI lowered emissions that caused air pollution while increasing performance of powerstroke diesel engines no matter at what speed the vehicle was traveling.

For diesel engines today, many HEUI injectors are being replaced with the high pressure common rail systems. One engine, the International 6.4L, was developed without an HEUI.

Replace Ford 7.3L 94-97 Injector

Replace Ford 7.3L 94-97 Injector

Draining the HPOP reservoir or the crankcase is not necessary prior to replacing this type of fuel injector. Start by removing the engine cover, CCV assembly, air filter, intercooler tubes and turbo intake hose. In addition, make sure to unplug the wiring harness before removing the side valve cover on the driver’s side of the vehicle. Start with the driver’s side first, where there is more room to maneuver yourself and your tools.

To unplug old injectors, flip down the clips holding them in place. Proceed to pull up on the wire plug in order to remove glow plugs. Then, gently take out the gasket and set it aside to be reused later.

Oil spouts will need removed with a five mm wrench. Your old oil spouts will be placed on the new injectors so lay them in a safe place where you can easily find them later. Next, detach each injector’s lower retaining bold with an eight mm socket. Leave the upper bolt alone because the injector collar easily slides away from the upper bolt.

Begin working with the rear injector and move forward since the engine’s angle permits most of the oil and fuel to drain into the last cylinder. Apply pressure with your prybar between the head’s top and the injector collar. Carefully remove the rear injector when it becomes free from its spot and continue on removing the remaining three injectors.

To soak up oil seeping from the holes, stick rags in the holes and crank the engine by hand several times. Also clean injector holes and make sure all copper washers were removed when you took out the injectors.

Using your 10 mm socket, remove glow plugs and then begin installing the new injectors. Lubricate them with engine oil before placing one in its hole. Seat each injector by giving it two or three good smacks with your hand once you have it firmly in the hole. Use the rubber mallet to secure all four injectors.

With your eight mm socket, torque the lower retaining bolts to 120 inches/pound and put back all oil spouts. Put the valve cover gasket back on and plug in all injectors, making sure the metal clips are secure. When replacing the VC cover, just tighten a couple of bolts since you still need to replace the old injectors on the passenger’s side of the car.

After reinstalling glow plugs, hook up the main wire harness and everything else you removed at the beginning of this project. Rebuild oil pressure by cranking the engine for about 25 seconds. Allow the starter to rest for a few minutes and then try another 15 second crank. If it doesn’t start, just let the starter rest a little longer. You will be able to hear the new injectors clicking prior to the engine firing.