Download Ford Power Stroke Diesel No-start Diagnosis

FORD
POWER STROKE
DIESEL NO-START
DIAGNOSIS
BY BOB PATTENGALE
Service opportunities on diesel-powered
vehicles are on the rise. If your shop is looking
for additional revenue, taking on the oil-burners
could be the ticket. But to be successful, you’ll
need the right tools and training.
H
ow do you approach a familiar no-start or driveability problem? Do you
jump right in, relying on
past knowledge of common problems, or do you
follow a set diagnostic strategy to ensure
nothing is overlooked.
What about when a vehicle manufacturer makes changes to the engine man-
36
November 2011
agement system? Do you take time to
understand the system first or do you
dive right into the diagnostic process,
hoping your experience wins out? What
happens if your first couple of educated
guesses don’t resolve the problem?
Effective and efficient repair of today’s vehicles requires an understanding of how each system operates before the diagnostic process begins. It’s
Photoillustration: Harold A. Perry; images: Thinkstock & Wieck Media
Don’t Start Something
You Can’t Finish
November 2011
37
FORD POWER STROKE DIESEL NO-START DIAGNOSIS
High-Pressure
Oil Rails
Oil
Filter
Oil Reservoir
for
High-Pressure
Pump
HighPressure
Oil Pump
Oil
Cooler
IPR Sensor
ICP Sensor
Drain to Crankcase
Fig. 1 This illustration shows the low-pressure and high-pressure oil systems for the 6.0L diesel engine. The fuel system
must have the correct oil pressure to operate, so oil-related problems are common causes of hard-start/no-start issues.
nice to have troubleshooter tips, but
there’s no substitute for a firm grasp of
how the components relate to one another and what happens when everything is working right.
Many assume top driveability technicians quickly diagnose problems because they’re able to complete all the
tasks in a fault tree the fastest or because they know all the common issues. The truth is they’re able to look
at the symptoms, make a logical decision on where the diagnostic process
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November 2011
should begin and then follow the best
path for resolution.
The opportunity to repair diesel vehicles is on the rise, and if your shop is
looking for additional revenue, diesel
repair can be it. To be successful you
need to have the right tools and technicians who understand how diesel systems work.
Ford diesel truck repair is a good opportunity. It’s also an excellent example
of how things can change very quickly.
In the past 10 years, Ford has offered
four different platforms—7.3L, 6.0L,
6.4L and now the 6.7L—and although
the basic combustion process for each is
similar, how the fuel is supplied to the
cylinders is very different.
This article will focus on a common
driveability complaint with the Ford
6.0L diesel engine, then explain how
the 6.4L fuel delivery system differs
from the 6.0L.
Hard-start and no-start complaints
are a common issue with Ford 6.0L
diesel engines, and experienced techni-
Courtesy Ford Motor Co.
Fuel Injectors
Oil
Pump
Photo courtesy Automotive Training Group, Inc.
cians are able to determine the root
cause very quickly. But they can do this
only because they understand how the
system operates.
Technicians with limited experience
will most likely begin with the “Hard
Start/No Start Diagnostic Guide” developed by Ford. We don’t have the space
to reproduce it here, but it can be found
at http://tinyurl.com/64dvmu5. This
comprehensive guide is designed to provide a logical diagnostic flow and help
the technician avoid overlooking potential issues, which from Ford’s perspective
will ensure that the vehicle is repaired efficiently and correctly the first time.
Technicians using this guide will locate the root cause, but they may not
understand why they’re performing the
steps listed. One example is step 2:
“Check Engine Oil Level – Check for
contaminants (fuel, coolant), Correct
Grade/Viscosity, Miles/Hours on oil,
correct level.” Engine oil quality and
level are critical for correct operation of
the fuel injectors and a common cause
of hard-start/no-start issues. Why is the
engine oil so critical?
Fig. 1 on page 38 shows a simple oil
flow schematic for the 6.0L diesel engine. In order for the fuel injectors to
operate, a minimum of 500 psi oil pressure is required for start-up. The highpressure oil pump can deliver up to
3600 psi, but only if the low-pressure oil
system delivers the oil to the high-pressure pump.
Understanding the low-pressure and
high-pressure oil systems is critical for
diagnosing hard-start/no-start problems,
so let’s take a closer look at these systems in detail.
The low-pressure oil system begins
with the oil pump drawing oil from the
oil pan. Oil pressure in excess of 70 psi
between the pump and oil cooler is
vented back to the oil pan.
The oil travels from the oil pump to
the oil cooler and any pressure greater
than 25 psi is diverted around the oil
cooler to the oil filter. The benefit is providing an alternative oil flow path during
high oil flow conditions.
This is what can happen when a customer skips preventive maintenance. Oil
sludge builds up and can damage the reservoir filter screen. Once the screen is
compromised, debris can enter the high-pressure pump.
The oil travels from the oil cooler to
the oil filter, and any pressure greater
than 20 psi bypasses the oil filter and
travels to the high-pressure reservoir.
The oil filter housing contains two critical valves: One is an oil change drain
valve that opens when the oil filter is
Understanding
the low- and
high-pressure
oil systems is
critical for
diagnosing
hard-start/nostart problems.
removed, allowing the oil to drain back
into the pan; the other is an antidrainback valve that uses a one-way check
valve to keep oil in the housing with the
engine off and the filter installed. This
ensures that oil is available on initial
start-ups.
The oil travels to the high-pressure
reservoir, where approximately 1 quart of
oil is stored. The high-pressure oil pump
draws oil from the reservoir through a 3in. screen designed to catch debris. The
photo above shows what can happen
when preventive maintenance is neglected. Keep in mind that once this screen is
damaged, debris will enter the highpressure pump and be carried through
the high-pressure system.
The high-pressure oil pump is driven
by the camshaft and produces the highpressure oil needed to properly operate
the fuel injectors. The pump is capable
of producing more volume and pressure
than is needed for normal operation,
and the excess volume is controlled by
the powertrain control module (PCM).
Next in line is the injection control
pressure (ICP) sensor, which measures
the oil pressure leaving the pump and
reports this to the PCM. The PCM uses
November 2011
39
FORD POWER STROKE DIESEL NO-START DIAGNOSIS
Here are two examples of where oil pressure may be lost in the high-pressure system. Injection pressure regulator (IPR)
damage (left photo) and O-ring issues (right) are very common causes of hard-start and no-start complaints.
the information from the ICP sensor to
regulate the oil pressure using the injection pressure regulator (IPR). This is a
duty-cycle-controlled solenoid that
opens and closes to achieve the desired
oil pressure. The IPR duty cycle for a
normal hot idle engine is approximately
30%. In order to maintain the correct
oil pressure, excess oil is diverted back
to the oil pan.
During engine start-up, the PCM
needs to see at least 500 psi. If the pressure is too low, the PCM increases the
duty cycle percentage; in other words, it
closes the IPR, creating a restriction to
increase the oil pressure. If the PCM
command reaches 85%, the IPR is fully
closed, which indicates a major problem
in the oil supply chain.
The photo above left shows a damaged IPR where the debris catch screen
is almost completely gone. IPRs are
common failure items and will normally
point to additional problems. For example, if you find the high-pressure oil
reservoir screen is damaged, then the
IPR will likely have debris present, and
if the IPR screen is damaged or
40
November 2011
clogged, the high-pressure oil reservoir
screen is likely damaged as well.
After leaving the high-pressure oil
pump, the oil travels through a series of
branch tubes, standpipes, passages,
During engine
start-up, the
PCM must
see at least
500 psi. If the
pressure is too
low, the PCM
closes the IPR.
high-pressure oil rails and finally the fuel
injectors. Keep in mind that these connection points will have O-rings sealing
the system. Fig. 1 cannot properly
demonstrate all the possibilities, but if
you look at where the lines connect to
the components described, each point
would likely have an O-ring. O-rings
should never be reused under any circumstance. We’ll discuss how to check
for leaks later in the article.
Steps 1 through 6 in the “Ford Hard
Start/No Start Diagnostic Guide” deal
with visual inspection, engine oil quality,
intake/exhaust restrictions, fuel quality
and fuel pump pressure and volume.
Steps 7 through 9 cover checking for diagnostic trouble codes (DTCs) and performing KOEO tests.
Experienced technicians will check for
DTCs first. If the following DTCs are
present—P1378, Fuel Injection Control
Module (FICM) voltage circuit low;
P0611, FICM Internal Failure; P0261,
P0264, P0267, P0270, P0273, P0276,
P0279 and P0282, All Fuel Injector Circuits are low; and/or U0105, Lost communication with FICM—the most likely
FORD POWER STROKE DIESEL NO-START DIAGNOSIS
cause will be a faulty FICM. Powers,
grounds and connections between the
FICM and PCM should be checked prior to replacement of the FICM.
In cases where the FICM connections
test okay, it’s always a good idea to check
for newer PCM/FICM calibrations. It’s
not uncommon to find TSBs where the
only fix is updating the controller software.
If no DTCs are present or if the
DTCs do not relate to a no-start condition, continue to step 10, Scan Tool –
Data List Monitoring. This is the step
where you really get to see what’s happening with the engine management
system. It lists eight specific parameters
that should be monitored while cranking the engine.
Fig. 2 These screen captures show the critical parameters that should be
watched while cranking the engine. The capture on the top is from a knowngood vehicle, while the one above is from a defective vehicle.
42
November 2011
The two screen captures in Fig. 2
show the parameters that should be
monitored while cranking the engine.
Keep in mind that if the battery voltage
drops below 9.5 volts, the scan tool
might reset. If this occurs, correct the
battery issue before continuing.
In this example, Engine Oil Temperature (EOT) is included but is not a parameter that needs to be monitored while
cranking. The initial note on the Diagnostic Guide is checking EOT. If it’s below 60°F and the vehicle will not start,
and the recommendation is to check the
Glow Plug System Operation first.
A – V PWR. Module Voltage
B – FICMLPWR. FICM Logic
Power
C – FICMVPWR. FICM Vehicle
Power. The Guide specifies 8 volts minimum for all three (A, B and C), but
above 9.5 is a real-world value. If the
voltage values are below the recommended specification, this should be
corrected first.
D – RPM. The form states 100 rpm
minimum, but a real-world value is
above 120 rpm. Low rpm can be caused
by electrical issues. If the value is 0, check
the crankshaft position sensor (CKP).
E – ICP. ICP Pressure. A minimum of
500 psi is required for injector operation.
As detailed earlier, there are many possible causes for low ICP pressure. The
possible causes could be located in the
low-pressure or high-pressure section.
F – ICP V. ICP Voltage. Minimum
voltage is specified as .80 volt while
cranking. Zero volts might indicate
wiring or connector issues.
G – Fuel PW. Injector pulse width
defaults to 0 without a CKP signal.
Range 500µS to 2mS.
H – FICMSYNC. No sync from the
FICM could be caused by camshaft
position sensor (CMP) or CKP faults.
The value should be YES after 120 rpm
is reached.
The Diagnostic Guide does not reference IPR % = Inj Press Reg, but this is a
critical parameter for checking the state
of oil system health. As discussed earlier,
IPR should be approximately 30% idling
FORD POWER STROKE DIESEL NO-START DIAGNOSIS
hot. If the value is higher or has reached
85%, there’s an issue with the oil system,
and it’s only a matter of time before a
hard-start or no-start issue develops. If
you service vehicles equipped with this
shows the vehicle running after warm
restart with the ICP pressure high. But
the pressure will continue to lower to
the desired level. The Inj Press Reg
percentage will continue to decrease
until the ICP desired pressure is reached.
The screen capture on
the bottom shows that the
vehicle will not start. The
voltage values are normal,
rpm is greater than 120,
sync from the FICM is normal. The ICP is below 500
psi and the Inj Press Reg
has reached 85%, which
means there’s an issue in
the oil system.
Fig. 3 graphically displays two vehicles while
cranking. The recording at
the top shows a vehicle that
will not start. The red vertical lines relate to the values
below the graph. In this
case rpm is good but ICP is
not capable of reaching 500
psi and the IPR is fully
closed. The bottom recording shows a vehicle that’s
operating properly. The
timeline shows that it takes
less than 4 seconds to start
and stabilize the injection
control pressure.
By now you should start
to see a trend. After a quick
glance at the other parameters, the primary focus
should be the ICP and the
IPR percentage. If the ICP
is unable to reach 500 psi,
you need to determine why.
Step 1: Check the lowside oil pump pressure. Also, pay close attention to
the oil filter and related
check valves.
Step 2: Using a scan tool
with IPR bidirectional conFig. 3 These are graphical examples of how the ICP, IPR and rpm work together. The screen trol, open and close the IPR
capture on top is from a known-bad vehicle that will not start, which had an oil pressure to see if any pressure change
leak; the screen capture above is from a known-good vehicle.
occurs. If nothing hap-
44
November 2011
engine on a regular basis, it’s not a bad
idea to check these values.
Now let’s take a closer look at the
two scan tool examples. In Fig. 2 on
page 42, the screen capture on the top
FORD POWER STROKE DIESEL NO-START DIAGNOSIS
pens, the IPR will need to be checked.
Step 3: The photo below shows an
adapter used to check for leaks at the
ICP port. The ICP is removed and the
adapter/air hose are installed. The
shop air pushes the oil out of the high-
pressure system through the IPR into
the oil pan. Once you hear the air flowing easily, use a scan tool to command
the IPR to 85%, which closes off the
high-pressure system. If the airflow
does not decrease, check the IPR. Now
Here are two test devices for diagnosing a no-start condition on a Ford 6.0L
Power Stroke diesel engine you cannot live without. The adapter with hose attached (top photo) is used to check for high-pressure leaks at the ICP. The two
block-off tools above check the high-pressure pump’s deadhead pressure.
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November 2011
use a stethoscope and listen for leaks.
Step 4: If no leaks are found, use the
high-pressure deadhead isolation tools
to determine if the high-pressure pump
can produce sufficient pressure. Follow
the manufacturer’s recommendations
for the proper test sequence. The pump
should be able to produce 1500 psi
while cranking and IPR over 60%.
One quick check to determine if ICP
is above 500 psi and the vehicle will not
start is to verify that the ICP is accurate.
Simply disconnect the IPR; if the vehicle starts, the ICP is out of calibration
and should be replaced.
If vehicle does not start, continue
with other non-oil-related issues. If you
skipped Steps 4 through 6 on the “Hard
Start/No Start Diagnostic Guide,” now
would be a good time to review the fuelrelated items. Check fuel quality, electric fuel pump pressure and fuel pump
inlet restriction. Keep in mind that one
bad injector will not create a no-start, so
if the oil-related systems test good, the
likely cause is fuel-related.
Unfortunately, we cannot cover all
possible causes and test sequences in
detail here, so it’s important to follow all
manufacturer recommendations.
As for the 6.4L diesel engine, one
critical difference between it and the 6.0
is that the 6.4L engine does not use a
high-pressure oil system for fuel injector
operation. It uses a high-pressure pump,
but it’s pressurizing diesel fuel, not oil. If
you decided to connect a scan tool looking for ICP, IPR or FICMSYNC, you
won’t find these parameters. You’ll be
monitoring parameters like pressure
control valve, volume control valve and
fuel rail pressure sensor.
In order to be accurate and efficient
when diagnosing Ford’s 6.0L diesel, you
need to understand the system you’re diagnosing. The most successful driveability
technicians do not rely on troubleshooting tips; they use a logical process based
on how the system functions.
This article can be found online at
www.motormagazine.com.