Jeep Diesel Diagnostics

2007-2008 3.0 L Jeep Grand Cherokee | 2005 – 2006 Jeep 2.8 L Liberty CRD


2007– 2008 Jeep OM642 Diagnostics

PDF: 2007 – 2008 Jeep OM642 Diagnostics

Note: The 3.0 L engine in the 2007 – 2008 Jeep is very similar to the engine used in the 3.0 L 2007 – 2009 Sprinter, both are manufactured by Mercedes. You may see some references to Mercedes codes down below, you should go by the code description and related diagnostics.

In order to do proper diagnostics, you will need a scan tool and some special tools available from Mopar Special Tools. As an inexpensive option, read our Blog Post on using a phone app and dongle for diagnostics
If you don’t have service information, you can buy a subscription online at alldatadiy.com or eAutorepair.net.

Piezo High Pressure Common Rail Basic Information

The high pressure pump builds rail pressure and delivers it to the fuel rail manifold, where it flows through the injector lines to the injectors. The fuel pressure regulator in the high pressure pump and the pressure regulating valve in the rail control rail pressure. The injectors have a piezo stack instead of an electromagnetic solenoid. When energized, the piezo crystals expand, lifting the control valve off of its seat via a hydraulic coupler (connecting plunger below) to begin injection. If the valve seat in the injector is leaking or the pressure regulating valve leaks, then it will not build enough rail pressure to start the engine.

CAUTION
The fuel system contains high pressure fuel up to 23,500 PSI. Do Not use your fingers to find leaks! High pressure fuel entering your bloodstream may result in amputation or loss of life.

Preliminary checks

  1. Record and repair any active DTC, they may be related to complaint
  2. Ensure that you have a good, clean fuel supply.
  3. Verify that battery voltage is above 12.0 volts.
  4. Verify that cranking speed is above 200 rpm

No Start or Hard Start

  1. First, verify rail pressure while cranking. If rail pressure matches desired and the engine will not start, there is another problem causing the no start. If the rail pressure does not reach desired, continue with fuel system diagnosis.
  2. No, or low fuel supply pressure to the high pressure injection pump (CP). See “Fuel Supply” below.
  3. Injectors; monitor rail pressure and see if you have over 3600 PSI, or 1.0 volt, during cranking. If not, one or more internally leaking injectors can cause a hard start. See injector section for further diagnostics. No smoke from the tailpipe after about 10 seconds of cranking means no fuel is getting into the cylinders. Buy Genuine Bosch OE Injectors
  4. Leaking fuel pressure solenoid (in fuel rail). There should be no fuel coming out of the solenoid while cranking. Perform the fuel rail pressure solenoid leak quantity test to determine if it is faulty. If the injectors check good, the fuel pressure solenoid should hold 870-1450 psi when unplugged during cranking. See “Fuel Pressure Solenoid” below for more information. Buy Replacement Fuel Pressure Solenoid
  5. If the above tests pass and rail pressure is still below spec, try unplugging the Fuel Quantity Control Valve (FCA) in the CP pump and see if the pressure goes up. If not, the pump may be bad.

Black Smoke

*Smoke may not be visible on DPF equipped vans. The exhaust may need disconnected, or a test pipe temporarily installed to diagnose smoking issues. Black smoke related problems will often cause frequent regenerations and premature DPF loading.

  1. Dirty air filter
  2. Exhaust leaks or Boost leaks, you can usually hear a boost leak as a high-pitched squeal under load.
  3. VGT turbo sticking and/or not operating properly.
  4. EGR system fault. Usually this will set a code.
  5. Dirty or damaged Mass Air Flow sensor
  6. Plugged intake manifolds and/or defective swirl valves

Miss, Rough Run, Knock

  1. A bad or incorrect torque on an injector, missing or damaged chamber gasket, low compression, excessive valve lash, flat lobes on camshafts could all cause a miss.
  2. Injector hold down bolts must be replaced if they are removed, they are a torque to yield bolt. If not, they could stretch and allow combustion gasses to blow past the injector, which can overheat the injector and cause it to fail.
  3. There is a relative compression test available using the wiTECH scan tool. Acceptable values between two cylinders must be equal to or less than 15 rpm.

Surge at idle

  1. Restricted or aerated fuel supply to the high pressure pump.
  2. Actual versus desired too far apart, map the fuel pressure graph, if you have a fluctuation over 500 psi this may cause a surge. It may be a bad fuel quantity solenoid valve (FCA) in the CP pump. Verify fuel pressure solenoid (in the rail, see below) operation before replacing the fuel quantity solenoid in the high pressure pump. Buy OE Flow Quantity Control Valve for Jeep

Blue-White smoke at idle when cold

*Smoke may not be visible on DPF equipped vans. The exhaust may need disconnected, or a test pipe temporarily installed to diagnose smoking issues.
If the smoke clears in less than 1 minute, this could be normal depending on temperature and altitude. Blue white smoke that burns your eyes is UN-burnt fuel. Cold temperatures, high altitude and excessive idle time all mean incomplete combustion.

  1. Possible bad injector, leaking at the nozzle tip.
  2. The intake air temperature, coolant temperature, inlet air temperature and battery temperature should all display normal ambient temperatures when cold. If not, repair as necessary.
  3. Check glow plug system operation when cold.
  4. Check rail pressure when engine is off, it should be 0 PSI (+/- 500 PSI).
  5. Aerated or restricted fuel supply.
  6. Excessive idle time can cause white smoke when cold due to carbon build up on injector tips. More than 20% idle time is excessive.

Fuel Supply

2007-2009 model years use an electric supply pump in the tank to feed the CP pump at 59 ± 2 PSI. Measure before and after the fuel filter to verify any possible filter restrictions. The fuel pressure relief valve (cascade overflow valve), in the CP pump, limits the fuel supply pressure to the fuel quantity control valve (FPR, FCA, MPROP). The fuel supply system also provides pressure to the return, or back leakage, side of the injectors. See “Injectors” for more information.
Fuel Pressure Solenoid, In Fuel Rail Buy Jeep Fuel Pressure Control Solenoid
⦁ The fuel pressure solenoid is attached to the rear of the fuel rail. The tip of the fuel pressure solenoid uses a knife edge, for metal to metal sealing. The knife edge actually deforms the metal in the fuel rail in order to seal the surfaces. The solenoid must be replaced if it is removed from the rail. The solenoid controls and maintains the rail pressure as commanded by the ECM.
⦁ In a DE-energized state, the fuel pressure solenoid is held closed by spring force, like a relief valve. During starting, the fuel pressure solenoid is held closed by magnetic force to allow enough pressure for starting. When plugged in, the fuel pressure solenoid should not leak any fuel out of the return during cranking.
⦁ When unplugged, it should hold 870-1450 PSI during cranking and should return some fuel. If it doesn’t hold pressure, and the injectors are OK, then the fuel pressure solenoid is bad.
⦁ When driving, the fuel pressure solenoid is constantly somewhat open, the pressure of the fluid counteracts the magnetic force of the coil and the slight spring force to help maintain desired rail pressure.
⦁ If the actual fuel pressure, vs the fuel pressure set point, gradually drops, and then spikes well above the set point, then the fuel pressure solenoid is sticking and usually needs to be replaced.

*To perform the fuel rail pressure solenoid leak quantity test, follow these steps:

  1. There are two types of lines going to the solenoid. One rubber line and one braided steel line. Disconnect the rubber return fuel line from the fuel rail. Plug the rubber fuel return to prevent leakage. Use a short section of hose to route the fuel from the rail into a suitable container.
  2. For the braided line disconnect the large fuel rail return hose at the banjo fitting and clamp it off. Attach hose to the banjo fitting and direct the hose into a suitable container.
  3. Crank the engine for 10 seconds. There should be no leakage out of the solenoid.
  4. If there is, check the pulse width modulated signal from the ECM. It is normally 18% to 24% when cranking or idling.
  5. If it is and there is leakage, replace the fuel pressure solenoid.

High Pressure Injection CP3 Pump Buy Bosch Rebuilt High Pressure Pumps

The high pressure pump is driven by the camshaft, and requires no timing. Fuel that enters the high pressure pump is pressurized between 200-1600 bar (2,900 – 23,205 psi). The pressurized fuel is then supplied to the fuel rail. The high pressure pump and flange located behind the pump are supplied as an assembly. Fuel passages and control elements in the flange regulate the flow of fuel to the high pressure pumping chambers, and control the lubrication of the pump.

  1. Most starting problems due to low rail pressure are caused by bad injectors or the fuel pressure solenoid in the fuel rail. If there is a leak in the injection system then the pump will not build enough pressure. If there has been a major contamination issue with dirt and or water then it is very likely that the high pressure pump will need to be replaced. The injectors are typically damaged first, but any contamination that got into the injectors also went through the CP pump.
  2. You can unplug the fuel quantity control valve, in the CP3, and the pressure should default to maximum (23,200 PSI).
  3. If the cascade overflow valve is bad this can send fuel out the return line instead of to the charging circuit of the CP pump.

Injectors Buy Bosch OE Injectors for Jeep Diesel

*The injector hold down bolts are torque to yield. They must be replaced when removed, they are one time use only! If they are not replaced, it will most likely lead to the injectors coming loose while running, and possible damage to the cylinder head.
The injectors incorporate piezoelectric actuators required for high-speed activation. The higher switching speed allows the intervals between individual fuel injections to be reduced and controlled more precisely. This feature contributes to a quiet and more efficient engine.
The engine requires a high number of injections during normal operation. At an engine speed of 1000 rpm, for example, the ECM may activate the injectors up to 250 times every second. Enough energy needs to be quickly stored to activate the injectors within these time constraints. The piezoelectric actuators also require high-voltage (150+ volts) for proper operation.
It takes about 3000 PSI rail pressure in order for the injectors to deliver fuel for starting. The injectors also require low fuel supply pressure on the return side to function. Without back pressure, the hydraulic coupler (connecting plunger) will have excessive clearance and the piezo actuator will not function correctly.

  1. Excessive leakage in the injector usually results in a starting issue, which could occur hot or cold, but usually occurs hot because the fuel is thinner when hot. Excess leakage from the injector is returned to the tank, it is not an external fuel leak.
  2. If the rail pressure is lower than specification and the fuel supply to the CP pump is good, check the injector return volume. Remove the engine covers. Disconnect the fuel return hoses at the top of the injectors. Install separate hoses and put in individual containers to measure the return volume. Pinch off the fuel return line to prevent pressurized fuel from the supply pump coming out of the return line while cranking. Each injector should have little to no return fuel while cranking, and must not exceed 2.5 ml in 10 seconds.
  3. The injectors can be very difficult to remove at times due to carbon build up around the injector body in the cylinder head. This is usually caused by leaking chamber gaskets. The hold down bolts are marginal at best, and if re-used after removal they will not hold torque. The bolts are torque to yield, they must be replaced any time they are removed. Buy Injector Hold Down Bolts

Turbocharger

The turbochargers on these engines are a variable geometry type turbo. They use an electric actuator, controlled by a pulse width modulated signal from the ECM, to vary vane position depending on load and throttle position. Like any of the other VGT type turbos, these turbos are susceptible to carbon build up causing the vanes to stick, resulting in several drivability problems. Most commonly these complaints would include poor response, low power, DPF loading, and poor fuel economy, among others. The turbocharger, charge air cooler and EGR system operate with one another and must be tested as a system. Buy Jeep OE Turbos

  1. Check the vane actuator for movement at key on and then when starting the engine. It should have full travel when the engine is started.
  2. The actuator can be replaced separately from the turbo, but the condition of the vanes in the turbo can also affect actuator movement. Free and full travel must be verified if replacing the actuator.

Swirl Valves
The 3.0L engine in the Jeep is equipped with a unique feature. Swirl valves help to improve low speed response and lower emissions. Per Chrysler:
“The intake manifolds feature swirl intake ports to reduce particulates at low engine speeds. Each cylinder incorporates one swirl port and one charge port. The swirl ports can be closed by the swirl valves. The valves are connected via a linkage which is operated by the swirl valve actuator.
The swirl valves are normally open by spring tension. The spring is integral with the swirl valve actuator. In the lower engine speed and load range, the swirl valves are closed by the swirl valve actuator. The entire air mass flows through the charge ports only, which results in greater swirling. The increased swirling produces uniform combustion for better engine performance and reduction of particulates. As rotational speed and load increases, the swirl valves open, so that optimal swirling and the required air mass are provided for the current operating conditions.”
These swirl valves are prone to sticking due to carbon build up in the intakes from the EGR system. The linkages are also prone to breaking or otherwise failing. When the swirl valves fail or stick, the engine will have very low power and codes related to the swirl valves. Some codes are not commonly found in service information. See the DTC list below for further information.

Diesel Particulate Filter

The diesel particulate filter traps soot from the exhaust to lower particulate emissions. During certain driving conditions, the engine will perform a regeneration cycle, which will use additional fuel injections and the catalyst to heat up the exhaust temps to the point where the soot will be burnt out and form ash. Over time, the DPF will become “ash loaded” and need replaced or cleaned.
Any engine drive-ability issues or fuel system failures will cause premature plugging or failure of the DPF. If the DPF is plugging repeatedly or requiring excessive regeneration cycles, there is probably another problem with the engine, fuel system, or EGR system.

  1. DO NOT reset the DPF timer unless the DPF has been replaced or cleaned (removed and cleaned, not regenerated in the vehicle). The ECM keeps track of fuel used, soot, and ash load. Excess soot and ash load will result if the timer is reset without replacing or cleaning the DPF.
  2. A plugged DPF can cause a turbo failure by forcing exhaust under excess pressure around the turbine shaft seals. Low boost/low power complaints must be diagnosed properly and completely prior to repairs!
  3. Excessive idle time will also cause DPF restriction due to particulate build up at idle. This will cause poor mileage (zero MPG when idling) due to more frequent regeneration events. Excess idle time could be defined as leaving the vehicle running while hooking up a trailer or loading/unloading.
  4. Using Stanadyne Performance Formula fuel additive, which improves cetane, will reduce regeneration events and improve mileage around town. This is due to a better burn when cold and fewer particulates getting to the DPF. Buy Stanadyne Performance Formula Use the following information regarding diagnostic trouble codes in addition to the normal diagnostic procedures outlined in the service manual or technical service bulletins.
    *Sprinter OEM codes do not start with a “P”, just four digits like “2626”. However, most service information sites use a P due to the standard OBD protocol. When searching for codes, try both configurations, for example “P2626” and “2626”. Also, many of the Sprinter codes will have a standardized OBD alternate, such as “P0299” for “2359”. Not all codes have the OBD counterpart, which tends to create some confusion as to which codes need to be addressed. OEM service information and scan tools are suggested for these reasons.

DTC Codes

DTC P0087 Fuel rail pressure malfunction- pressure too low
*This code is not listed in Chrysler service literature for Sprinter, but may set or show with some scan tools.

  1. Restricted or aerated fuel supply to CP3 pump
  2. Excessive leakage from fuel injectors
  3. Fuel pressure solenoid in fuel rail not operating correctly

DTC P0201 – P0206 Injector control circuit short to ground/voltage or “general error”

  1. Damaged injector wiring
  2. Check injector resistance. It should be 185k ohms +/- 10%.

DTC P0299 Turbo under boost condition
*This code is not listed in the Chrysler service information for Sprinter, but it is an OBD2/Global code that can be stored in the Sprinter ECM and will show with some scan tools, often in conjunction with P2359 or in place of.

  1. Cracked and/or leaking plastic turbocharger resonator
  2. Leaking charge air cooler tubes, hoses, or seals from turbo, intercooler or intake
  3. Dirty or Damaged MAF sensor
  4. Other boost leaks and or exhaust leaks (before the turbocharger)
  5. Turbo and or VGT system failure- VGT actuator stuck open
  6. EGR valve sticking or other EGR system failure
  7. Plugged air filter
  8. Plugged DPF

DTC P0300 Misfire detected

  1. Restricted or aerated fuel supply
  2. Defective injector(s)
  3. Fuel injector hold down lost torque, chamber gasket leaking
  4. Use scan tool to isolate each cylinder
  5. Perform Fuel Correction Test with scan tool to isolate cylinders
  6. Damaged cams and/or lifters

DTC P2025 Intake pressure sensor plausibility

  1. Basically a barometric pressure/intake restriction sensor. Mounted on air box and is often damaged during service or other repairs

DTC P02043 Camshaft position sensor circuit- open circuit

  1. Usually defective cam sensor, however occasionally a bad crank sensor may set this code.
  2. Often sets in conjunction with P2045 crankshaft position sensor circuit lost signal

DTC P02045 Crankshaft position sensor circuit lost signal

  1. Usually defective cam sensor, however occasionally a bad crank sensor may set this code.
  2. Often sets in conjunction with P2043 camshaft position sensor circuit-open circuit

DTC’s P2133 Cylinder 1, P2134 Cylinder 2, P2135 Cylinder 3, P2136 Cylinder 4, P2137 Cylinder 5, P2138 Cylinder 6 Glow Plug Open, Short Circuit, or Excess Temperature
(May also show as P0671, P0672, P0673, P0674, P0675, P0676)
⦁ Check glow plug system as outlined in service information. Almost always caused by bad glow plugs and/or module.

DTC P2359 Boost pressure too high/too low
⦁ Many scan tools will show a P0299 code in place of this code. 2359 is the code listed in Chrysler literature.

  1. Most commonly sets due to a cracked and/or leaking turbocharger resonator assembly.
  2. Other boost leaks at intercooler, intercooler piping/hoses, etc.
  3. Sticking VGT actuator
  4. Plugged air filter
  5. Restricted DPF
  6. Defective turbocharger

DTC P2510 Boost Pressure Regulator Circuit Performance, P0046 Turbo Boost Control Circuit Performance (Jeep)
⦁ This code indicates that the VGT actuator is operating outside a normal position range and is usually associated with a severe lack of power. Boost or turbo intake leaks are often the culprit, however defective turbos and actuators are not uncommon.

  1. Check for boost leaks at intercooler, intercooler piping/hoses, seals, ETC.
  2. Inspect turbo inlet ducting for loose clamps and/or connections.
  3. Verify VGT actuator function with a scan tool
  4. Defective turbocharger

DTC P2513 Swirl Valve Motor Position Error, P1270 Intake Manifold Runner Performance (Jeep)
⦁ It is not uncommon for scan tools to not have a description or correct description for this code. (Sprinter)

  1. Check the swirl valve linkage for range of movement. It can be actuated using some scan tools and should move key on engine off. The valves commonly stick and do not allow movement.
  2. Inspect the swirl valve linkage and sensors. If the linkage is loose or broken, or the sensors are loose/out of position, this code may set.
  3. Replacement of the swirl valve assemblies is recommended if the valves are sticky/stuck, the linkage is worn/broken, or if the motor is bad. Cleaning the intakes and valves usually is only a temporary fix.

DTC P2621 Diesel Particulate filter, Ash Accumulation High
⦁ May also show as “P242F”, which is the OBD2 code alternate
⦁ This code is usually just what the description states- a restricted DPF. The DPF can be restricted by a number of things, including: driving habits, fuel system/engine failures, sensor failures.
⦁ The vehicle may just need to be driven at steady highway speeds for 45 to 90 minutes to clean the DPF.

  1. Check for any other engine related codes and repair as needed first.
  2. Inspect the entire exhaust system to be sure there is no damage, leaks, or modifications.
  3. If the exhaust system checks ok, attempt a manual regeneration. It may take multiple attempts to get the DPF to burn out completely. In some cases the DPF may need to be removed for cleaning at a service facility or replacement.
  4. If the regeneration was successful, test drive the vehicle to see if the fault returns. If it does, check the DPF differential pressure sensor for skewed readings and replace as needed, then re-test.

DTC P2626 Diesel Particulate Filter- Soot Content Too High
⦁ This code is usually just what the description states- a restricted DPF. The DPF can be restricted by a number of things, including driving habits, fuel system/engine failures, sensor failures.
⦁ The vehicle may just need to be driven at steady highway speeds for 45 to 90 minutes to clean the DPF.

  1. Check for any other engine related codes and repair as needed first.
  2. Inspect the entire exhaust system to be sure there is no damage, leaks, or modifications.
  3. If the exhaust system checks ok, attempt a manual regeneration. It may take multiple attempts to get the DPF to burn out completely. In some cases the DPF may need to be removed for cleaning at a service facility or replacement.
  4. If the regeneration was successful, test drive the vehicle to see if the fault returns. If it does, check the DPF differential pressure sensor for skewed readings and replace as needed, then re-test.

DTC P2952 Left Swirl Valve Position Sensor Fault, P2953 Right Swirl Valve Position Sensor Fault
⦁ It is not uncommon for scan tools to not have a description or correct description for these codes.

  1. Check the swirl valve linkage for range of movement. It can be actuated using some scan tools and should move key on engine off. The valves commonly stick and do not allow movement.
  2. Inspect the swirl valve linkage and sensors. If the linkage is loose or broken, or the sensors are loose/out of position, this code may set.
  3. Replacement of the swirl valve assemblies is recommended if the valves are sticky/stuck, the linkage is worn/broken, or if the motor is bad. Cleaning the intakes and valves usually is only a temporary fix.


2005 – 2006 2.8 L Jeep Liberty Diesel

PDF: 2005 – 2006 2.8 L Jeep Liberty Diesel

In order to do proper diagnostics, you will need a scan tool and some special tools available from Mopar Special Tools. As an inexpensive option, read our Blog Post on using a phone app and dongle for diagnostics.

If you don’t have service information, you can buy a subscription online at alldatadiy.com or eAutorepair.net.

High Pressure Common Rail Basic Information

The high pressure pump builds the high pressure and delivers it to the fuel rail manifold, which buffers out pressure fluctuations and distributes fuel to the individual injectors. The fuel quantity solenoid (fuel control actuator, M-Prop) in the high pressure pump controls pressure output from the pump. The fuel pressure solenoid (pressure control valve) in the fuel rail has final control of rail pressure and prevents over pressurizing of the system. The injectors have a hollow check ball that holds rail pressure until the fuel solenoid is actuated by the ECM, this allows the check ball to rise off its seat and an injection to take place. If the check ball in the injector is leaking or the fuel pressure solenoid is defective, then it will not build enough rail pressure to start the engine.

Dodge-Diesel common rail diagnostcis

CAUTION

The fuel system contains high pressure fuel up to 23,500 PSI. Do Not use your fingers to find leaks! High pressure fuel entering your bloodstream may result in amputation or loss of life.

Preliminary Checks

  1. Record and repair any active DTC, they may be related to complaint.
  2. Ensure that you have a good clean fuel supply.

No Start or Hard Start

  1. No or aerated fuel supply to the high pressure injection pump (CP3)
  2. Monitor rail pressure and see if you have over 2,900 PSI during cranking, if not one or more injectors leaking internally can cause a hard start, see injector section for further diagnostics. No smoke from the tailpipe after about 10 seconds of cranking means no fuel is getting into the cylinders. Buy Jeep 2.8 CRD Injectors
  3. Fuel filter head sucking air. Install a clear fuel line between filter and high pressure pump to check for air. The fuel heaters in the filter head are known to melt the electrical connector and suck air. Remove the connector from the filter head and inspect for melted plastic and/or heat damage. An update is available from Chrysler to fix this issue.
  4. Leaking fuel pressure solenoid (in fuel rail). There should be no fuel coming out of the solenoid while cranking, and it should hold 870-1450 psi when unplugged during cranking. If it doesn’t, and the injectors are OK, then the fuel pressure solenoid is bad. Buy Jeep CRD Fuel Pressure Solenoid
  5. If other work has just been performed, be sure that the #4 injector connector and the fuel pressure solenoid connectors are not swapped. This will cause the fuel pressure solenoid to dump pressure and the engine will not start.

Black Smoke

  1. If at idle, use the scan tool to cut out one cylinder at a time and see if the smoke disappears.
  2. Dirty air filter
  3. Exhaust leaks or Boost leaks, you can usually hear a boost leak as a high pitched squeal under load.
  4. VGT turbo sticking and/or not operating properly.
  5. EGR system fault. Usually this will set a code.
  6. Dirty or damaged Mass Air Flow sensor
  7. Worn or damaged engine camshafts and followers (see DTC P0101)

Miss

  1. Perform the “Fuel Correction Test” with a scan tool. During the test, the values should fluctuate slightly above or below 0 mg/stroke. If the values increase to +6 or -6 mg/stroke or more, it would indicate a balance issue with that cylinder.
  2. A bad or incorrect torque on an injector, missing or damaged chamber gasket, low compression, excessive valve lash, flat lobes on camshafts could all cause a miss.
  3. There is a relative compression test available using the DRB3 or wiTECH scan tools. Acceptable values between two cylinders must be equal to or less than 15 rpm.

Knocks

  • Use scan tool to isolate one cylinder at a time

Surge at Idle

  1. Restricted or aerated fuel supply to the high pressure pump. Observe the fuel pressure set point vs. the actual fuel pressure, if the actual fuel pressure oscillates above and below the set point, check for air intrusion in the fuel supply.
  2. Actual versus desired too far apart; map the actual fuel pressure vs. the set point pressure, if erratic and there is no air in the system, it may be a bad Fuel Quantity Solenoid (fuel control actuator). If you have a fluctuation over 500 PSI, this can cause a surge. Fuel contamination can cause the Fuel Quantity Solenoid to become sticky and erratic. Buy Jeep Liberty 2.8 Fuel Pressure Regulator

Slow Deceleration

  • If the engine hangs at higher rpm or is slow to decelerate, injector wear is what normally causes this problem due to excessive return. Injectors will need to be replaced.

Blue-White Smoke at Idle When Cold

If the smoke clears in less than 1 minute, this could be normal depending on temperature and altitude. Blue white smoke that burns your eyes is unburned fuel. Cold temperatures, high altitude and excessive idle time all mean incomplete combustion.

  1. Possible bad injector, leaking at the nozzle tip. Use the scan tool to kill one injector at a time to isolate, or unplug one injector at a time. However, this does not reduce rail pressure in the injector and the tip can still leak fuel.
  2. Perform the “Fuel Correction Test” with a scan tool. During the test, the values should fluctuate slightly above or below 0 mg/stroke. If the values increase to +6 or -6 mg/stroke or more, it would indicate a balance issue with that cylinder.
  3. The intake air temperature, coolant temperature, inlet air temperature and battery temperature should all display normal ambient temperatures when cold. If not, repair as necessary.
  4. Check glow plug system operation when cold.
  5. Check rail pressure when engine is off, it should be 0 PSI (+/- 500 PSI).
  6. Aerated or restricted fuel supply.
  7. Excessive idle time can cause white smoke when cold due to carbon build up on       injector tips. More than 20% idle time is excessive.

Fuel Supply

  1. Similar to the Duramax engines, these engines do not use a fuel supply pump. The CP3 pump pulls fuel through a fuel filter unit mounted on the fire wall. Because these systems are under vacuum, not pressure, they are more susceptible to air intrusion into the fuel system.
  2. The fuel filter heads are a known problem on these engines, and there is an updated filter head assembly available through Chrysler. The biggest problem is the fuel heater connector tends to fail, allowing air into the fuel supply. Use a clear fuel line to check for air in the fuel supply to the high pressure pump.
  3. Worldwide, in other markets, these used a fuel supply pump in the tank. The ECM has a fuel pump driver built in and there is a relay and fuse in the fuse box, and wiring to the rear of the vehicle for a fuel supply pump. It is possible to install a different module in the tank with a fuel supply pump and the correct wiring harness to upgrade the fuel supply system. This is recommended if the engine is equipped with a tuner and/or other performance upgrades. It will also help the gear pump in the CP3 last longer and minimize the chance of other fuel supply issues.

EGR System

  • The EGR system on this engine can set multiple codes, due to multiple issues, some as simple as a vacuum line problem. To properly diagnose, you need to use your scan tool and follow the diagnostic procedures for any DTC codes that may set.

High Pressure Injection Pump (CP3 Pump) Buy Jeep Liberty CRD High Pressure Fuel Pump

  1. Most starting problems due to low rail pressure are caused by bad (check ball seat) injectors or the fuel pressure solenoid in the fuel rail.
  2. You can unplug the fuel quantity solenoid, on the CP3 pump, and the pressure should default to maximum (23,500 PSI), however during the first 30 seconds (during starting) the fuel quantity solenoid is inactive. If there is a leak in the injection system, then the pump will not build enough pressure.
  3. To attempt to look at volume out of the high pressure pump may be misleading, the 5.9 Dodge only puts out 70 ml (cc) in 30 seconds at cranking. There is no specification from Chrysler, but I would expect the volume to be half of the 5.9 Dodge. If there has been a major contamination issue with dirt and or water, then it is very likely that the high pressure pump will need to be replaced. The injectors are typically damaged first, but any contamination that got into the injectors also went through the CP3 pump.
  4. If the cascade over flow valve is bad this can send fuel out the return line instead of to the charging circuit of the CP3 pump.
  5. If you have a surge, observe the fuel pressure set point vs. the actual fuel pressure, if the actual fuel pressure oscillates above and below the set point check for air intrusion in the fuel supply. If there is no air in the system, a sticky fuel quantity solenoid can cause this problem.

Fuel Pressure Control Solenoid, In Fuel Rail  Buy Jeep Liberty 2.8 Fuel Pressure Control Solenoid

  1. The fuel pressure solenoid is attached to the rear of the fuel rail. The tip of the fuel pressure solenoid uses a knife edge, for metal to metal sealing. The knife edge actually deforms the metal in the fuel rail in order to seal the surfaces. The solenoid must be replaced when ever it is removed from the rail. The solenoid controls and maintains the rail pressure as commanded by the ECM.
  2. In a DE-energized state, the fuel pressure solenoid is closed. During starting, the fuel pressure solenoid is held closed by magnetic force. When checking the fuel pressure control solenoid, there should be no fuel coming out the return during cranking, and it should hold 870-1450 psi when unplugged during cranking. If it doesn’t, and the injectors are OK, then the fuel pressure solenoid is bad.
  3. When driving, the fuel pressure solenoid is constantly open; the pressure of the fluid counteracts the magnetic force of the coil and the slight spring force to help maintain desired rail pressure.
  4. If the actual fuel pressure, vs. the fuel pressure set point, gradually drops and then spikes well above the set point then the fuel pressure solenoid is sticking and usually needs replaced.
  5. Low rail pressure under load, and a P0093 code, can be caused by a defective fuel pressure solenoid. Check for return with the engine running, and if possible, use a scan tool to run the high pressure set point test. There should be minimal to no return from the fuel pressure solenoid. If there is more than 15-20cc in 30 seconds, the valve is likely bad. A good solenoid will typically not leak any fuel while cranking or at idle.

Injectors – Buy Liberty 2.8 CRD Injectors

It takes about 2,900 PSI rail pressure in order for the injectors to deliver fuel for starting.

  1. Excessive leakage usually results in a starting issue, which could occur hot or cold, but usually occurs hot because the fuel is thinner when hot. Excess leakage is due to wear, which would be greatly accelerated due to fuel contamination. If the injector has excessive leakage that fuel goes out the return system, it is not an external leak.
  2. Per Chrysler, unplug the cam sensor and plumb the individual injector returns into graduated vials. In 10 seconds of cranking, the highest return should be no more than 3ml higher than any other injector. Any injector with 3ml more return would need to be replaced, per Chrysler.
  3. If removed from the engine and sent in, we can test the injectors to be sure they meet factory specifications and provide replacements for any that do not meet specifications.

Turbocharger  Buy New Replacement Liberty CRD Turbo

  • The turbochargers on these engines are a VGT (Variable Geometry Turbocharger) type turbocharger. They use a vacuum actuator to vary vane position depending on load and throttle position. Vacuum to the actuator is controlled by the boost pressure solenoid, which is controlled by the ECM. Like any of the other VGT type turbochargers, these turbos are susceptible to carbon build up causing the vanes to stick, resulting in several drivability problems. Most commonly these complaints would include poor response, low power, black smoke, and poor fuel economy, among others.
  • A turbocharger failure will usually be accompanied by diagnostic trouble codes pertaining to boost pressure (MAP), intake air volume (MAF), or EGR. Some common codes are P0299 Turbocharger under boost condition, P0101 Mass air flow sensor signal negative deviation, P0401 EGR solenoid circuit negative deviation.

Glow Plug System

  • These engines were originally equipped with ceramic glow plugs. As of 2011 the ceramic glow plugs are no longer available through Mopar. The ceramic glow plugs have been superseded with a metallic glow plug.
  • When replacing one or more ceramic glow plugs with metallic glow plugs, it will be necessary to replace all four glow plugs, the glow plug control module, and reprogram the engine control module. All changes must be done at the same time, but only should need to be done once. After the update, individual components can be replaced.
  • Ceramic glow plugs can be identified by using sand paper to scuff the oxidation off of the plug. Ceramic glow plugs are white in color. Metallic plugs are gray in color.

Timing Belt

The timing belt, pulleys, and tensioner need to be replaced at 100,000 mile intervals.

Use the following information regarding diagnostic trouble codes in addition to the normal diagnostic procedures outlined in the service manual or technical service bulletins.

DTC Codes

DTC P0087; Fuel rail pressure malfunction- pressure too low

  1. Perform re-flash per TSB 18-007-05 (2005 Model Year)
  2. Restricted or aerated fuel supply to CP3 pump. Observe the fuel pressure set point vs. the actual fuel pressure, if the actual fuel pressure oscillates above and below the set point check for air intrusion in the fuel supply.
  3. Excessive leakage from fuel injectors
  4. Fuel pressure solenoid in fuel rail not operating correctly

DTC P0093; Fuel rail pressure malfunction- maximum positive deviation

  1. Perform re-flash per TSB 18-007-05 (2005 Model Year)
  2. Plugged fuel filter.
  3. Aerated fuel supply to CP3 high pressure pump. Observe the fuel pressure set point vs. the actual fuel pressure, if the actual fuel pressure oscillates above and below the set point check for air intrusion in the fuel supply.
  4. Malfunctioning fuel quantity solenoid (FCA) in CP3 pump.
  5. Malfunctioning fuel pressure solenoid in fuel rail. If the actual fuel pressure, vs. the fuel pressure set point, gradually drops and then spikes well above the set point then the fuel pressure solenoid usually is bad and needs replaced.
  6. Low rail pressure under load, and a P0093 code, can be caused by a defective fuel pressure solenoid in the rail. Check for return with the engine running, and if possible, use a scan tool to run the high pressure set point test. There should be minimal to no return from the fuel pressure solenoid. If there is more than 15-20cc in 30 seconds, the valve is likely bad. A good solenoid will typically not leak any fuel while cranking or at idle.

DTC P0101; MAF sensor signal negative deviation

  1. Perform re-flash per TSB 18-007-05 (2005 Model Year)
  2. Plugged air filter
  3. Dirty/damaged MAF sensor
  4. Air leaks in turbo inlet ducting AFTER the MAF sensor
  5. Faulty turbocharger
  6. EGR system malfunction
  7. Engine mechanical failure
  8. Plugged catalytic converter
  9. If the air intake, charge air cooler and hoses, turbocharger, intake manifold, EGR system, and exhaust system check ok, then it is possible there is an internal engine problem causing low air flow. Most commonly this is caused by worn or damaged camshafts and followers. MAF voltage should run around 4.5 volts under hard load on a good running engine with no other issues. Engines with bad camshafts, in our experience, have run in the 3.8-4.0 volt range with low power and heavy black smoke. MAF should read between 1.6-1.9 volts at idle with the EGR valve disabled (Unplugged, or preferably blocked off to prevent any possibility of exhaust flowing into the intake. This can be accomplished by temporarily installing a thin metal plate under the EGR tube flange connection at the valve.).

DTC P0105; Turbocharger inlet pressure signal plausibility

  • Most likely cause is a failed boost pressure sensor

DTC P0201 – P0204; Injector control circuit

  1. Damaged injector wiring
  2. Check injector resistance, should be less than 1 ohm and greater than zero ohms (zero ohm meter leads before test).

DTC P0299; Turbo under boost condition

Set Conditions-Actual boost pressure differs from the boost pressure set point by more than 1000hpa. The boost pressure set point is calculated from MAF sensor input. A dirty MAF sensor will skew the value and cause the P0299 code.

  1. Perform re-flash per TSB 18-007-05 (2005 Model Year)
  2. Dirty/Damaged MAF sensor
  3. Boost and/or exhaust leaks
  4. Turbo and/or VGT system failure- VGT actuator stuck open
  5. EGR system failure
  6. Plugged air filter
  7. Plugged catalytic converter

DTC P0300 – P0304; injector misfire, all and 1 through 4

  1. Perform re-flash per TSB 18-007-05 (2005 Model Year)
  2. Restricted or aerated fuel supply.
  3. Defective injector(s), perform Fuel Correction Test with scan tool to isolate cylinders
  4. Damaged cams and/or lifters

DTC P0340; Camshaft position sensor circuit missing signal

  • Monitor the CKP and CMP signals. There are cases where a bad CKP code will cause a CMP code and vice versa. If the pattern from the CKP is not correct, then replace the CKP.

DTC P0401; EGR solenoid circuit negative deviation

The EGR Solenoid circuit negative deviation code takes a delta measurement from the MAF sensor during EGR valve operation. A dirty MAF sensor can skew the reading and cause a P0401 code.

  1. Perform re-flash per TSB 18-007-05 (2005 Model Year)
  2. Defective EGR valve
  3. Leaks around EGR cooler and/or cooler connecting hoses
  4. Damaged/Dirty MAF sensor
  5. Plugged catalytic converter
  6. Turbocharger and/or VGT system failure

DTC P1252; Vacuum reservoir solenoid short circuit

  • Internal failure in vacuum reservoir solenoid
  • Solenoid coil resistance should be 28-30 ohms