I just ordered a new 2011 Duramax so I have been snooping around about the new powerplants. Found some cool info that may be interesting for the diesel guys!

Will EFIL support this controller?

The Emissions Challenge

Meeting these new requirements by engine hardware changes alone has proven to be extremely difficult. However, the advanced aftertreatment technologies of the new Duramax diesel engines (Fig. 1) have shown great effectiveness in dealing with these emissions.





Fig. 1
Two new Duramax diesel engines were developed to meet the 2010 Federal emission standards for oxides of nitrogen (NOx) and particulate matter (PM). They reduce NOx to 0.2 grams per brake horsepower per hour (g/bhp-hr). The 2007 standard was 1.2 (g/bhp-hr).

Engine Applications

The 6.6L Duramax diesel engine (RPO LGH, VIN code L) is used on 2010 interim and 2011 Express and Savana (GMT 610) vans and 2011 Silverado and Sierra (GMT 900) trucks with RPO ZW9 (chassis cabs or trucks with pickup box delete).

The 6.6L Duramax diesel engine (RPO LML, VIN code 8) is used on 2011 Silverado and Sierra pickup models.

Mechanical Features

These engines use an iron block and aluminum cylinder heads. The bore and stroke are unchanged. The main bearing has been changed to enhance oil film thickness, and oil pump flow is increased.

In the cooling system, the thermostat is equipped with bleed holes to improve bleeding air from the system. The thermostat must be positioned with the bleed holes oriented toward the front of the engine.

An oval air filter is used on vans and a flat panel air filter is used on pickups. Also on pickups, the charge air cooler system has plastic lock rings on the inlet and outlet ducts. Use care when removing the lock ring to avoid damage. Twist the lock ring counterclockwise to release the tabs.

A single variable nozzle turbocharger (VNT) is used. The oil feed has been relocated from the number 4 cam bearing to a dedicated supply port at the left rear of the engine valley. The turbo mounting bosses have been revised. On the LGH engine, one boss was removed and another was added. On the LML engine, one boss was revised and another was added.

The EGR valve and stepper motor are contained in one unit. The position sensor now reflects the true position of the valve -- the valve moves when the stepper motor extends or retracts.

A single EGR cooler is used on the LGH engine for Express and Savana van applications, and a dual cooler is used on the LGH engine for Silverado and Sierra truck applications. The LML engine for the pickups also uses a dual cooler with an EGR cooler bypass controlled by the ECM to prevent coking of the EGR cooler during light load and idling.

Fuel System Features

The fuel system supply side is equipped with a fuel filter vacuum switch (Fig. 2) near the fuel filter. The switch opens if there is a restriction on the supply side, indicated by a vacuum of 13.6 - 15 Hg.




Fig. 2
The fuel system high pressure side uses a two-chamber pump that generates 200 megaPascals (mPa) of pressure (29,000 psi). Two high pressure lines feed the right fuel rail. A transfer tube carries fuel to the left fuel rail. A Fuel Rail Pressure sensor (FRP) is located on the rear of the left fuel rail.

The high pressure pump is timed so the peak pressure pulses match the injection events. Matching the pressure pulses results in a more constant pressure within the fuel rails. If the pump is removed, it must be retimed when it is installed. There are timing marks on the pump gear and camshaft gear that must be aligned, following SI procedures.

Two Fuel Rail Pressure Regulators (FRPR) are used. FRPR1 is still located on the injection pump as on previous Duramax engines. FRPR2 is located on the front of the left fuel rail. This solenoid is normally open. The ECM supplies pulse width modulation to change the duty cycle of FRPR2 to control the amount of fuel returned to the fuel tank.

The new Duramax engines are equipped with Bosch piezoelectric fuel injectors. These injectors operate a high voltage, indicated by the orange color of the injector harness.

IMPORTANT: Do not make contact with the fuel injector harness, ECM or fuel injectors while the ignition is in the On or Run position. Use certified insulated gloves EL-48286. These Class 0 gloves are rated at 1000 v. Check for functionality and check the expiration date of the gloves.

The ECM supplies high voltage and provides a ground. Voltage is supplied up to 160v at 20 amps, and can peak up to 240 v. This causes the injector to open. The capacitor discharges through an injector for initial opening and holds open with 12 v.

Injectors are grouped into four pairs: 1-4, 6-7, 2-5, and 3-8. If a condition is detected in a group, that group is disabled and a DTC is set.

On the fuel system return side, the return lines are now equipped with snap-in connections. The return side is under pressure.

A pressure retention valve maintains 0.4 to 1.1 mPa of pressure within the return lines to provide proper fuel injector operation.

TIP: Improper injector return line pressure may cause a no-start or performance concern.

If the engine runs out of fuel, or if the fuel system is serviced, the system must be primed. After priming, a feed line from the low pressure side of the pump backfills the injector return lines. The feed line will also backfill if pressure falls below 0.3 mPa in the injector return lines.

Electronic Control Features

The Bosch E86 ECM is larger and has three connectors instead of two. It also controls the HCI (Hydrocarbon Injector), FRPR 2, DEF pump, and DEF injector. The ECM has more than 160 new DTCs and you can use the Tech 2 to communicate with it.

TIP: This ECM will be on parts restriction for six months.

TIP: During programming, the download to the ECM should not be interrupted for the first 10% to 15% of the information transfer, or the ECM may not be recoverable for service.

The Glow Plug Control Module (GPCM) is located on the alternator bracket on the right side of the engine. The GPCM also provides regulated B+ for the NOx sensors and reductant heaters.

Electrical Features
On the pickups, a mega fuse block is part of the battery postive cable assembly. It contains a 175 amp main fuse that protects the UBEC and generator, a 125 amp glow plug control module fuse, and a 175 amp intake air heater fuse.
TIP: On vehicles with two generators, there is a second 175 amp fuse for the additional generator.


Aftertreatment System

The new Duramax diesel engines use an aftertreatment system (Fig. 3) to reduce oxides of nitrogen (NOx) by 90%. This system features a :
A. Diesel Oxidation Catalyst (DOC)
B. DEF injection and mixer
C. Diesel Exhaust Fluid (DEF)
D. Selective Catalyst Reduction (SCR)
E. Diesel Particulate Filter (DPF)
F. Exhaust cooler


Fig. 3
SCR technology permits NOx reduction to occur in an oxidizing atmosphere. It's called selective because it uses ammonia to reduce NOx levels as a reductant within a catalyst system. The reducing agent is automotive-grade urea -- also known as Diesel Exhaust Fluid (DEF) or Emission Reduction Fluid (ERF) -- that reacts with NOx to convert the pollutants into nitrogen, water and trace amounts of CO2. The urea is quickly hydrolyzed to produce oxidizing ammonia.

Two NOx sensors are used. Each sensor and its associated smart module are permanently connected and are serviced as a unit. Sensor 1 reads engine-out NOx. Sensor 2 reads SCR-out NOx. Sensor information is used by the ECM to adjust DEF dosing to the SCR. Sensor 2 allows the SCR system to detect poor DEF control and a damaged SCR catalyst.

The ECM controls the DEF delivery system. Based on engine NOx emissions level as communicated by calibration tables in the ECM or by the NOx sensor feedback, the ECM will send a command to the DEF injector to dose a given quantity of DEF. The injected DEF mixes with the exhaust gas with the help of a mixer before contacting the SCR. The SCR brick stores the ammonia, and by way of a chemical reaction with the NOx in the exhaust gas, produces nitrogen (N2) and water.

Diesel Particulate Filter

The DPF operates the same as on previous engines to remove diesel particulate matter, or soot, from the exhaust. The regeneration parameters are still based on time, distance, fuel and soot loading, but the algorithms used to determine regeneration now allow more time between generation events.

A Hydrocarbon Injector (HCI) is located on the right side of the engine, with a nozzle located in the exhaust downpipe between the turbo and the Diesel Oxidation Catalyst (DOC). Diesel fuel is injected into the exhaust system ahead of the DOC to raise the temperature of the exhaust for DPF regeneration.

TIP: HCI replaces the late post injections used in previous engines, although late post injections can be used if there's a fault in the HCI system.

HCI is triggered when ECM data indicates that the conditions for regeneration have been met.