2010 ASTON MARTIN V8 VANTAGE Workshop Manual

AML EOBD System Operation Summary

Rory O’Curry Aston Martin Lagonda CONFIDENTIAL 1 May 2009
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Dual MAF Diagnostic Overview

The dual MAF diagnostic performs 11 separate tests on the measured MAF values. Each test is designed
to identify specific faults many of which, are only applicable to the dual MAF hardware configuration.
Many of the tests compare the measured MAF values to the estimated MAF (calculated from throttle
position, barometric pressure, act and engine speed). The tests are performed continuously (apart from the
conditions outlined later) and are always completed in the same sequence:

Test1 - Does MAF1+MAF2 = estimated MAF
Test2 - Does MAF1 = ½ estimated MAF
Test3 - Does MAF2 = ½ estimated MAF
Test4 - Is MAF1 Test5 - MAF1 low voltage
Test6 - MAF2 low voltage
Test7 - MAF1 high voltage
Test8 - MAF2 high voltage
Test9 - Is MAF1> estimated MAF
Test10 - Is MAF2> estimated MAF
Test11 - Does MAF1 = MAF2

By pass/fail combinations of the above tests a vari ety of conditions can be detected discretely on each
MAF:
Partly blocked MAF
Fully blocked MAF
Electrical short to ground MAF
Electrical short high MAF
Backflow
Failed in range MAF

AML EOBD System Operation Summary

Rory O’Curry Aston Martin Lagonda CONFIDENTIAL 1 May 2009
Fault Matrix
ConditionMAF 1 + MAF 2 = EST
MAF 1 = ½ EST
MAF 2 = ½ EST
MAF 1 < MAF 2
MAF 1 low voltage
MAF 2 low voltage
MAF 1 high voltage
MAF 2 high voltage
MAF 1 > EST
MAF 2 > EST
MAF 1 = MAF 2Air Charge P-codes
Normal operating. YY--------f(maf_raw)
None
MAF 1 partly blocked. N-N----f(maf_raw)
P010F, P0100
MAF 1 fully blocked @ low load.
Y-N---- f(maf_raw)
P010F, P0100
MAF 2 partly blocked. -N-N- - -f(maf_raw)
P010F, P010A
MAF 2 fully blocked @ low load. -Y-N---f(maf_raw)
P010F, P010
AMAF 1 shorted to ground.
-Y-N----f(maf_raw)
P0102
MAF 1 shorted to high. -N-Y----f(maf_raw)
P0103
MAF 1 failed in range. -N-N----f(maf_raw)
P0101
MAF 2 shorted to ground. --Y-N---f(maf_raw)
P010C
MAF 2 shorted high. --N-Y---f(maf_raw)
P010D
MAF 2 failed in range. --N-N---f(maf_raw)
P010B
Estimated value wrong. --
Yf(maf_raw)None
MAF 1 and MAF 2 failed in range. --Nf(fmem)
P0101, P010B
Backflow via MAF 1. -
Y-f(fmem)
P0104
MAF 1 short to ground MAF 2 failed in rng. -N-f(fmem)
P0102, P010B
MAF 1 shorted high, MAF 2 failed in rng. -NN
YN---f(fmem)
P0103, P010B
Backflow via MAF 2.Y-- f(fmem)
P010E
MAF 1 failed in rng, MAF2 short to ground. N- -f(fmem)
P0101, P010C
MAF 1 failed in rng, MAF 2 shorted high. NNN
Y---f(fmem)
P0101, P010D
MAF 1 & MAF 2 shorted to ground. -YYNN---f(fmem)
P0102, P010C
MAF 1 & MAF 2 shorted high. -NNYY---f(fmem)
P0103, P010D
Severe backflow via MAF 2.Y-- f(fmem)
P010E
MAF 2 fully blocked @ high load N- -f(fmem)
P010F, P010B
Severe backflow via MAF 1. -
Y-f(fmem)
P0104
MAF 1 fully blocked @ high load. -N-f(fmem)
P010F, P0101
YNNY N
N
NN - NNNN
-
-NYY N
-NYNN
-YNN
Y
N
NY
Y
NN
YN
























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AML EOBD System Operation Summary

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Dual MAF Diagnostic Operation:
DTCs P0100 – Mass Air Flow A Circuit
P0101 – Mass Air Flow A Circuit Range/Performance
P0102 – Mass Air Flow A Circuit Low Input
P0103 – Mass Air Flow A Circuit High Input
P0104 – Mass Air Flow A Circuit Intermittent/Erratic
P010A – Mass Air Flow B Circuit
P010B – Mass Air Flow B Circuit Range/Performance
P010C – Mass Air Flow B Circuit Low Input
P010D – Mass Air Flow B Circuit High Input
P010E – Mass Air Flow B Circuit Intermittent/Erratic
P010F – Mass Air Flow Sensors A/B Correlation
Monitor execution Continuous (exceptions below)
Monitor Sequence Continuous (exceptions below)
Sensors/Components OK No Throttle Position Failure
No Vehicle Speed Failure
Monitoring Duration Continuous (exceptions below)

Global Entry Conditions
Entry condition Minimum Maximum
Battery Voltage 11 volts 18 volt

Global Abort Conditions
SAIR monitor running

Abort Conditions for P0100,P0101,P010A,P010B,P010F
Throttle position < 3 degrees & Vehicle Speed > 15mph

AML EOBD System Operation Summary

Rory O’Curry Aston Martin Lagonda CONFIDENTIAL 1 May 2009
SAIR Monitor

SAIR Hardware

The V8 uses SAIR to enhance the emissions performan ce. The SAIR pump is supplied with clean air from
the ‘Y’ junction prior to the throttle. This air is th en supplied to the exhaust via two vacuum operated
valves, which are controlled from a common electrically operated control valve.


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Clean
air pipe

Vacuum
valves
Electric
valve
Air supply
to exhaust
Secondary
Air Pump

AML EOBD System Operation Summary

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SAIR System Monitor – Flow Check

When the air pump is energized, the MAF sensor will show a corresponding increase in airflow. The
SAIR pump flow check monitors the MAF sensor signal and two air flow models during normal
secondary air system operation to determine if secondary air is being delivered into the exhaust system.
The SAIR pump flow test compares the actual change in MAF during the pump on and off transitions to
the expected change in airflow from the secondary air fl ow model. (A throttle body flow model is used to
"zero out" errors in the air meter and to compensate fo r transient driving conditions.) The actual airflow is
divided by the expected airflow to calculate an "On flow ratio" and an "Off flow ratio".

A flow ratio that is much less than 1.0 means that the air pump has no/low flow, or the inlet hose to the
pump is disconnected. If secondary air system operation ex tends into closed loop fuel, fuel trim feedback
is used to discriminate between low pump flow and in let hose disconnection. A low flow ratio with a lean
fuel system indicates a disconnected inlet hose. A flow ratio significantly higher than 1.0 (and/or a rich
fuel system indication) indicates that th e outlet hose from the pump is disconnected.

SAIR Diagnostic


The V8 uses the standard FORD non-intrusive monitor that has been adapted for use on a V-engine. The
detection capability is detailed below with the V8 specific modifications highlighted

P0410 - Pump inlet hose disconnection.

P0491 - Low airflow into the exhaust on Bank1. Blocked hose OR failed to open vacuum valve.

P0492 - Low airflow into the exhaust on Bank 2. Blocked hose OR failed to open vacuum
valve.

P2448 - Low airflow into the exhaust on Bank1. Disconnected outlet hose.

P2449 - Low airflow into the exhaust on Bank 2. Disconnected outlet hose.

P0412 - SAIR electrical circuit fault high/low on ecu control pin.

P2257 - SAIR electrical circuit fault high on monitor pin.

P2258 - SAIR electrical circuit fault low on monitor pin.

The determination of which bank is receiving low ai rflow is performed by monitoring the closed loop
fuelling correction supplied from the oxygen sensors. The bank that has the highest enleaning correction is
the bank that has the lowest SAIR flow. If closed loop fuelling is not active when the SAIR pump is
disabled the diagnostic cannot determ ine which bank is receiving low flow and so a fault on both banks is
raised.

The relative difference between the commanded lambda values for each bank is used to determine a
restricted flow to either bank1 or 2 due to a restricted outlet. This enables P0491, P0492 to be raised if the
flow ratio is calculated as in range.

The SAIR functional tests run when SAIR is active and the results are stored until the HEGO monitor has
completed (150-200 seconds after SAIR is off on a typical FTP74). It is only when the HEGO monitor has
completed successfully that any functional SAIR fa ults and SAIR monitor complete is reported.

AML EOBD System Operation Summary

Rory O’Curry Aston Martin Lagonda CONFIDENTIAL 1 May 2009
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SAIR Diagnostic High Level Flow


AIR Monitor Flow Check Operation: onitor Flow Check Operation:
DTCs P0491 Pump Low Flow Bank1
P0492 Pump Low Flow Bank2
P0410 Pump Inlet Hose Off
P2448 Pump Outlet Hose Off Bank1
P2449 Pump Outlet Hose Off Bank2
P0412 primary side circuit check
P2257, P2258 secondary side circuit checks
Monitor execution Flow check - once per driving cycle, circuit checks – continuous
Monitor Sequence Runs approx. 5 seconds after start during normal SAIR operation
Sensors OK ECT, IAT, MAF, TP, ETC, and HO2S
Monitoring Duration From 5 to 70 seconds

Typical AIR flow check entry conditions: (The monitor will run when the air pump
runs, the entry conditions below are secondary air system entry conditions.) re secondary air
system entry conditions.)
Entry condition Minimum Maximum
Time since engine start-up 5 seconds 70 seconds
Engine Coolant Temperature -7oC (20oF) 35oC (90oF)
Predicted Pump Flow 18.5kg/h (0.68lb/min)
Manifold Vacuum 13.2kPa (3.9”Hg)
Catalyst Temperature 847oC (1558oF)
Inlet Air Temperature -12oC (10oF)
Battery Voltage 11 volts 18 volts
Note: There is a Throttle position stability ch eck that can delay the calculation of the flow ratio. If the throttle is continuously moving, it is
possible, to delay calculation of the flow ratio.

Typical AIR functional check malfunction thresholds:heck malfunction thresholds:
On Flow ratio < 0.75 (P0491, P0492 - Low Flow or, P0410 - Inlet Hose Off)
Off Flow ratio < 0.75 (P0491, P0492 - Lo w Flow or, P0410 - Inlet Hose Off)
Fuel Shift >0.3/Long term fuel shift bank1/bank2 (Clears possible outlet blocked P0491/92, but leaves valid P0410)
Bank1 – Bank2 lambda correcti on error >0.5 (P0491, P0492)
Closed Loop Fuel Control Active >10 seconds (P0491, P0492 – Low Flow)
On Flow ratio > 1.58 (P2448, P2449 – Outlet Hose Off)

AML EOBD System Operation Summary

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VCT Monitor

Variable Cam Timing System Monitor
VCT Hardware

Variable Cam Timing (VCT) enables rotation of the camshaft(s) relative to the crankshaft (phase-shifting)
as a function of engine operating conditions. Intake Only (phase-shifting only the intake cam) is used in
the AML application.

VCT is used primarily to increase internal residua l dilution at part throttle to reduce NOx, and to
improve fuel economy. With Intake Only VCT, the in take camshaft is advanced at part throttle and WOT
(at low to mid-range engine speeds) to open the in take valve earlier for increased residual dilution and
close the intake valve earlier in the compression stroke for increased power. When the engine is cold,
opening the intake valve earlier warms the charge which improves fuel vaporization for less HC
emissions; when the engine is warm, the residua l burned gasses limit peak combustion temperature to
reduce NOx formation.

The VCT system hardware consists of a contro l solenoid and a pulse ring on the camshaft. The PCM
calculates relative cam position using the CMP input to process variable reluctance sensor pulses coming
from the pulse ring mounted on the camshaft. Each pul se wheel has N + 1 teeth where N = the number of
cylinders per bank. The N equally spaced teeth are used for cam phasing; the remaining tooth is used to
determine cylinder # 1 position. Relative cam position is calculated by measuring the time between the
rising edge of profile ignition pickup (PIP ) and the falling edges of the VCT pulses.

VCT Diagnostic

The PCM continually calculates a cam position error value based on the difference between the desired
and actual position and uses this information to cal culate a commanded duty cycle for the VCT solenoid
valve. When energized, engine oil is allowed to flow to the VCT unit thereby advancing and retarding cam
timing. The VCT logic calculates the instantaneous va riance in actual cam position (the squared difference
between actual cam position and commanded cam position), then calculates the long term variance using a
rolling average filter (Exponentially Weighted Moving Average).
If the VCT system is stuck or operates with an consta nt error relative to the target position, the monitor
will detect a variance which will quickly accumulate. There are three variance indices that monitor cam
variance in the retard direction, the advance directi on, and for V engines, the difference between banks. If
any variance index is greater than the malfunction threshold, a VCT target error malfunction will be
indicated (P0011, P0012 Bank 1, P0021, P0022 Bank 2).

The VCT solenoid output driver in the PCM is check ed electrically for open circuit and shorts (P0010
Bank 1, P0020 Bank 2).
VCT Monitor Operation:

AML EOBD System Operation Summary

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