29400-01071 PUMP ASSY, SUPPLY Denso Cross

System Operation
The PEEC III 3406 Diesel Truck Engine is an electronically-controlled 3406. PEEC III controls fuel rate and timing electronically instead of using flyweights and linkages. The electronics also replaces the mechanical fuel-air ratio control, torque control group, and various adjustment screws.PEEC III uses several sensors as inputs to control two basic functions: rack and timing. Operation of each of these are similar. PEEC III decides where it wants to position the rack or timing advance. It then varies the voltage to the solenoid (BTM) to move the rack or timing to the desired position. Position sensors tell PEEC III when rack or timing is at the desired position.Electronic Controls
The electronic controller consists of two main components: the Electronic Control Module (ECM) and the Personality Module. The ECM is the computer which controls the PEEC engine. The Personality Module is the software which controls how the computer behaves. The two must be used together: neither can do anything by itself.Rack Controls
The rack mechanism on a PEEC III engine is very similar to a mechanical 3406 engine. The fuel injection pump is nearly identical; the rack is moved by a servo valve which receives oil pressure from the fuel injection pump. However, the PEEC III servo spool is moved by a solenoid (BTM) rather than by a linkage controlled by flyweights and springs.PEEC III determines a "desired rpm" based on the throttle position, vehicle speed, customer specified parameters, and certain diagnostic codes. The PEEC III governor tries to maintain the desired rpm by sensing actual engine speed using the engine speed sensor, then controlling the rack to achieve the desired rpm.PEEC III RPM Control Logic To move the rack, PEEC III adjusts the voltage to the rack solenoid (BTM) to increase rack. More voltage results in more rack. PEEC III knows how far the rack went by reading the rack position sensor. PEEC III increases the voltage to the rack solenoid until it senses the rack is in the desired position.PEEC III Electronic Governor PEEC III sets certain limits on rack motion. "FRC Rack" is a rack limit based on fuel-air ratio control, for emissions purposes. It works similar to a mechanical engine FARC; when PEEC III senses a higher boost pressure (more air into cylinder), it increases the FRC Rack limit, which allows more fuel into the cylinder. "Rated Rack" is a rack limit based on horsepower of the engine. It is similar to the rack stops and torque springs on a mechanical engine. It provides horsepower and torque curves for a specific engine family and rating. All of these limits are programmed by the factory into the personality module.Timing Advance Controls
The timing advance mechanism is the same as the 3406 mechanical engine, except the Timing solenoid (BTM), instead of the flyweights, controls timing advance. PEEC III adjusts voltage to the timing solenoid to change timing advance. More voltage results in more timing advance. PEEC III knows how much advance was achieved by reading the timing position sensor.