The PCM (Powertrain Control Module) is the main computer that controls the engine, and the transmission if it is an automatic. All in all, they are very well designed and normally last hundreds of thousands of miles. The single biggest killer is people pulling their chips out with the key on, frying the microprocessor, and often the EEPROM and chip.

7.3 PCM F-Series Automatic

7.3 PCM F-Series Manual

7.3 PCM Excursion

7.3 PCM E-Series Van

7.3 PCM Testing

The 7.3L Power Stroke

The 7.3L Power Stroke engine was released in the summer of 1994. It was considered to be the successor to the 7.3L Indirect Injection, although the only thing the two engines have in common is their displacement. Other than being 7.3 liters, not one single part is the same.

It's biggest distinction at the time is that it was the first computer controlled diesel engine sold in the United States.

A computer controlled diesel is the norm now; then it was revolutionary. Before then, the injection timing on a diesel was essentially fixed. You set it at 12* BTDC at idle, and it was still 12* BTDC at 3,000 RPM. It was 12* at -20*F below zero, and it was 12* at 250*F engine coolant temperature. It was 12* at zero PSI of boost, and it was 12* at 25 PSI of boost.

With the Power Stroke, the injection timing became infinitely variable: there were timing maps (lookup tables) that adjusted the injection timing for any altitude from sea level to 10,000', for any oil temperature from -10* to +290*, for any boost from zero to 21 PSI, and any injected fuel quantity from zero to 100 mg/cyl, and more...on the fly, updating the value every engine revolution.

The other new technology it pioneered was electronically controlled,  independent injectors. Prior to this, most diesels used either an injection pump that metered fuel to each injector, often called a Pump-Line-Nozzle system (PLN), or a Mechanical Unit Injector (MUI) where each cylinder had its own injector, but the injectors were activated by a camshaft or rocker arm  system the activated a plunger in the injector to pressurize the fuel. In other words, in a PLN system, the plungers are mechanically activated by a cam in the pump, and in a MUI system the plungers are activated by a cam on the injectors.

In the Hydraulic Electronic Unit Injector (HEUI) system on the Power Stroke, the force for activating the plungers in the injector came from engine oil pressurized by a High Pressure Oil Pump (HPOP), while when the injectors actually fired, how long they fired for, and at what pressure they injected the fuel, was all controlled by the Powertrain Control Module (PCM).

We break the 7.3 down into 4 generations:

First is the 1994.5-1997 F-Series trucks and 1994.5-1996 E-Series vans, which use a DPC-20x PCM.

Second is 1997 California F-Series and 1997 Vans, which use a DPC-31x PCM. Everything from 1994 through 1997 got a ZF 5-Speed manual transmission or an E4OD automatic transmission.

Third is the Early-99 F-Series trucks and Vans, both Federal/49-State and California Emissions, which use a DPC-40x or 41x PCM. Everything from Early-99 on got a ZF 6-Speed manual transmission or a 4R100 automatic.

Fourth is the Late-99 through early-2003, the end of production of the 7.3 in the US, which use DPC-42x through 49x PCM's.

Although Ford made trucks in 1998, there wasn't really a 1998 model year. In our view, if the truck has the old (square) body style, it's a 1997, and if it has the newer rounded-hood and fenders and an intercooler, it's an Early-99 / Super Duty, regardless of what the build date is.

If the build date is after 12-06-1998, then it is a Late-99 or 2000 model.

The Early-99 was a complete redesign of the entire cab, chassis and drivetrain, and some significant changes to the injectors, turbo, fuel system, etc on the engine. Then, after barely 6 months of production, for some reason Ford did another redesign, changing all sorts of other things, most of it for no apparent reason. (Why change the front wheel bearing unit hub flange from 3/8” thick to 10mm thick? It just meant that if you got the wrong unit bearing, your brake calipers wouldn't line up with the mounting bracket or brake rotor.)