Dodge Ram Diesel Engine Evolution

Emission components

NOx - oxides of nitrogen:

• One of the primary diesel engine pollutants, NOx is formed by reaction between oxygen and nitrogen in the combustion chamber.  NOx formation dramatically increases with increasing combustion temperature, combustion efficiency,  and combustion pressure.
• NOx emissions can be reduced by reducing power, lowering the intake air temperature, retarding the injector timing, reducing the coolant temperature, and/or reducing the combustion temperature. These often reduce fuel economy.

• Another primary diesel engine pollutant, PM is  formed when when insufficient air or low combustion temperature prohibits the complete combustion of free carbon. PM is partially unburned fuel or lube oil and is often seen as black smoke.
• PM emissions can be reduced by reducing oil consumption, higher fuel injection pressures, increasing the power output, reducing engine speed.

• HC is a minor pollutant of diesel engines which consists of unburned fuel, visible as white smoke when the engine is cold.

• Not a major problem with diesel engines because of the high air to fuel ratio.

The 1991 "Super B" diesel

Improvements to meet Jan 1, 1991 EPA standards

• Charge Air Cooling - reduces the intake air temp to 120 degrees F and reduces NOx.
• Turbocharger boost reduced to control NOx
• Turbine housing increased from 18 to 21 sq cm
• Head Casting improvements - to improve fuel combustion and reduce PM
• intake ports modified to increase intake swirl to a factor of 3.5
• injector bore diameter reduced from 9 mm to 7 mm
• Piston bowl geometry modified to enhance intake swirl
• Larger piston pin bearing area - increased to handle increased cylinder pressure
• Piston to piston pin and piston pin to connecting rod bearing tolerances tightened
• Torque plate cylinder honing used to control oil consumption, PM, and HC emissions
• Piston top compression ring finished with a lapped surface
• 3 grades of pistons used to mate the piston to each bore
• Injector bores reduced from 9 mm to 7 mm and fuel pressure increased

• improved cylinder head bolts and head bolt torque procedures
• three lengths of bolts
• increased thread length
• improved head gasket with more metal banding, and a thicker crush ring around the cylinder
• new piston cooling nozzles with a larger diameter and longer length for improved piston cooling
• 16% more flow from the oil pump to feed the piston cooling nozzles
• Larger oil cooler Oil pressure regulator and spring replaced to improve oil pressure regulation

• turbine housing reduced to 18 sq cm to answer complaints of low power

The 1994 "Killer B" diesel (begins January 1 1994)

1994 models built from July 1993 to January 1, 1994 DO NOT have catalytic converters.

Improvements to  meet Jan 1, 1994 EPA standards

• Inline Bosch P7100 injector pump for higher injection pressure an more precise timing
• 52 pound pump required stronger and wider gear housing for support
• Fuel lines redesigned for higher injector pump output
• Fuel filter relocated from a head casting to an intake manifold bracket
• Piston rigs moved up - top ring changed from 14 mm to 8 mm from piston top to reduce "dead space" and cut
• Piston pin bore and connecting rod bushing reduced to tighten piston / pin / rod clearance
• To withstand increased load from valve train:
• Camshaft material changed from chilled iron to chilled ductile iron
• Cam lobes widened, lobes machined for finer surface finish
• camshaft tappet faces hardened
• Wastegate added to H1C turbocharger (WH1C), 12 cm turbo housing  replaces 18 cm housing
• Filter Minder add to indicate intake restriction
• Catalytic converter added after Jan 1, 1994
• Clutch weight reduced and clutch engagement improved
• larger harmonic balancer used on 175 hp crankshaft
• prop shaft damper added to reduce drive train pulses

• Holset HX35W wastegated turbocharger replaces the WH1C.

• Piston rings lowered so that top ring is 14 mm from piston top
• CA engines rated for 180 HP and use EGR valve

• OBD-II required on PCM

The 1998 ISB diesel (begins January 1 1998)

ISB Improvements over the 12 Valve Cummins TurboDiesel
Information obtained from TDR issues and Chrysler Master Tech No 2  February 1998.

• New piston design features a symmetrical combustion bowl
• (combined with vertical centered injector and higher injector pressures) for improved power, fuel efficiency and oil control
• New vertically housed thermostat is easier to access for service and has fewer leak paths for improved in-cab heating
• New electronic fuel system improves engine control, driving performance, engine cleanliness and provides engine/vehicle diagnostics
• New Bosch VP44 Electronic Fuel Injection Pump has higher injection pressures, electronically controlled  timing and fueling for precise, instant control. The pump is driven at half the engine speed by the front gear train to reduce operating noise
• New engine-matched Holset turbocharger is custom-designed for high-speed ratings and wastegated for improved engine performance at all speeds
• New fuel filter has an integral water separator and water-in-fuel sensor. An environmentally friendly cartridge is rated at five microns
• New 24-valve cylinder head produces improved air and coolant flow, more torque over a wider range and improved fuel economy with reduced emissions
• New valve train has wider lobes on the tappet face, on the cam, and longer push tubes.
• To reduce camshaft wear, an electric lift pump eliminates the need for a mechanical lift pump lobe.
• The 60 pound standard valve springs are compatible with engine braking
• New single-piece valve cover allows faster access and easier servicing
• No-adjust overhead has improved lubrication and  requires its first check at 96,000 miles to reduce scheduled maintenance
• The EGR valve (CA) and catalytic converter are eliminated.

See Master Tech Issue 2 from Feb 1998 for more ISB details

1999 ISB engine changes (begins July 1998)

• Diesel towing capacity has been increased
• To reduce oil pressure during a cold start, excess oil from the pressure regulator is now routed to the sump instead of the lub pump inlet.
• A new turbo charger wastegate mount is located on the compressor cover. As before, the wastegate dumps boost at 20 psi.
• The thermostat is redesigned for increased reliability.
• The fuel injection pump bracked has been strengthened for improved durability; it is now cast instead of stamped

2000 ISB engine changes (begins July 1999)

• The red and silver aluminum valve cover replaced by a black and silver magnesium cover.
• The wiring harness was revised to plug directly into the fuel transfer (lift) pump, which no longer has a pigtail connector.
• The fuel filter is redesigned resulting in a new top loading fuel filter housing and filter element.
• The low pressure fuel system added fuel inlet and outlet pressure test ports. Fuel line routing changed to accommodate the test port connections.
• A 10 cm2 HY35W turbocharger replaced the HX35W turbo.

2001 ISB engine changes (begins Jan 1, 2000)

• 235hp / 460 ft. lb. ETC engine installed in 5-speed and automatic equipped trucks
  • ETC continues to use a 10cm2 HY35
• 245hp / 505 ft. lb. ETH engine became available with the DEE 6-speed.
  • ETH returns to the 12cm2 HX35W turbocharger.
  • ETH receives a higher output fuel injection pump.
  • Compression ratio is increased from 16.3 to 17.0.

2001.5 ISB engine changes (begins July, 2000)

• None reported

1998-2002 ISB Engine Components Specific to Chrysler

Fuel Injection Pump – Chrysler ISB engines are equipped with the Bosch® VP44 fuel pump. The VP44 fuel pump used for Chrysler ratings has a unique fueling map to obtain higher governed speeds. The Chrysler ISB injection pump is not interchangeable with other ISB fuel pumps. The VP44 is an electronically controlled rotary distributor fuel pump and is controlled by the Cummins ECM.

Engine Mounted ECM – The Cummins ECM is mounted on the left side of the engine block below the fuel filter. The ECM controls the Bosch® VP44 fuel pump by issuing fueling commands based on engine speed, load, and accelerator position. It also monitors the sensors on the engine to be sure that it is operating properly. The ECM logs fault codes generated internally to the Cummins electronic system as well as fault codes generated by the Bosch® VP44 fuel pump.
This ECM is specific to the Dodge pickup application. It is equipped with a single 50–pin connector which allows it to connect to engine mounted sensors as well as to the trucks electronic system. For this reason, other ISB ECMs, engine harnesses, and calibrations cannot be installed on Dodge trucks.

Wiring Harness – The wiring harness has a 50–pin connector that is specific to the Dodge pickup application. It connects the engine-mounted sensors, as well as the Dodge chassis computer (JTEC), to the Cummins ECM.

Throttle Position Sensor (TPS) – The TPS assembly is engine mounted and is specific to the Chrysler ISB application. The TPS is calibrated by the manufacturer and is not field adjustable. This part is available through the Chrysler parts network.

Electronic Service Tools – INSITE™ Version 4.2 in conjunction with INLINE™2 datalink adapter will have the capability of communicating with the Chrysler ISB engine. The service tool connection can be found above the fuel pump and will be a 3–pin Deutsch plug connection. A 2–pin Weatherpack connection is also available for datalink power.