Looking for the "Understanding Cerb Diagnostics" thread
Discussion
If you post up a screen grab of your traces I can decifer it for you and make reccomendations if you want a 2nd opinion 
Stage 1 of it all is making sure the lamdas are both working properly (i.e. bounce from low to high every 2 seconds or so when car is at a warm idle). When they are working they will shift the adaptives to make the mixture right - you then play with TPOts to get respective banks adaptives from -10 to 0. You also pray that your linkrod is correct, as then you don't have to worry about balancing them relative to eachother
Stage 1 of it all is making sure the lamdas are both working properly (i.e. bounce from low to high every 2 seconds or so when car is at a warm idle). When they are working they will shift the adaptives to make the mixture right - you then play with TPOts to get respective banks adaptives from -10 to 0. You also pray that your linkrod is correct, as then you don't have to worry about balancing them relative to eachother
Help on real-time Display
The real-time display has 4 screens.
Use the PgUp and PgDn keys to toggle between them.
The first screen is the main screen and it is called the engine monitor screen
it shows all the main inputs and outputs of the ECU.(Press PgDn whilst in help
to find HELP for other real-time screens)
SCREEN 1 - ENGINE MONITOR SCREEN
INPUTS
ENGINE SPEED
Engine speed is displayed in RPM and it should correspond to actual engine speed.
Spurious or non-existent readings denote a faulty sensor or sensor wiring. Check
sensor for damage, metal debris on its end, corrosion or water in its terminals,
and correct polarity (see wiring diagram )
THROTTLE POSITION
Throttle position is displayed as a percentage of throttle potentiometer movement.
15% corresponds to a fully shut throttle, 94% to a fully open one. Idle position
is at approx. 19%. There are two throttle position sensors, one for each bank.
Page down to the third real-time screen to display throttle pot. readings only.
Throttle pot readings should be equal on both banks to within a few percent, and
must not fluctuate more than 3%. The readings should increase smoothly with
increasing throttle travel and remain approximately equal on both banks. If the
ECU detects a fault with one of the throttle pot readings it will substitute the
value from the other throttle pot, so they will both display EXACTLY THE SAME
READING.
AIR TEMP
Air temperature is measured by the sensor by the side of the air filter. If the
ECU detects a fault with this reading it will substitute a value of 10 degrees C.
WATER TEMP
Water temperature is measured by the sensor in the metal water pipe underneath the
trim panel in the front of the engine bay.If the ECU detects a fault with this
reading it will substitute a value of 95 degrees C. The engine cooling fans are
controlled by this temperature reading, and are turned on at 92 deg C, off at
88 deg C. Therefore under fault conditions the cooling fans will be turned on.
BATTERY VOLTAGE
Battery voltage is displayed in volts. It should normally read between 12.0 & 13.8V
There is no default value.
BAROMETRIC PRESSURE
Barometric pressure is measured from the left hand air box and is displayed in mBAR.
It should correspond to the air pressure as measured on a barometer. If the ECU
detects a fault with this reading it will substitute a value of 1000 mBAR. The
pressure sensor is mounted inside the car to protect it from excessive heat. If
incorrectreadings are displayed, check the pipe between the sensor and airbox for
blockages or leaks.
LAMBDA 1 & LAMBDA 2
Lambda 1&2 show the signals from the lambda sensors on each bank. After starting the
sensors will take at least 30 seconds to warm up, before they will read correctly .
Once warmed up, the lambda signals should switch between approx. 0 & 1-1.5 volts.
0 volts shows that the fuel mixture is lean, 1 volt shows that the mixture is rich.
The rate of switching will alter with engine speed, and the percentage of time spent
rich relative to lean will alter with engine load. If reading is a CONSTANT 0 V, check
sensor for proper connection, and sensor heater wires for continuity (6 ohms between
white red wires)
NOTE: Lambda sensors are supplied with 12V on the red wires ONLY WHEN THE
FUELPUMP IS RUNNING, the WHITE wire is earth and BLACK the signal.
OUTPUTS
FUEL 1 & FUEL 2
Fuel injection time is displayed for each bank. When water temp >80 C at idle it
should be between 2.2 & 2.4 ms. Higher readings than this could indicate misfiring
due to fouled plugs, incorrectly balanced throttle assemblies, or faulty lambda
sensor readings. Check primary exhaust pipe temperatures to detect poorly running
cylinders, and check cylinder airflow with syncrometer to detect poor balance. If
all cylinders are running correctly check lambda sensors as above, replace if
faulty. If a cylinder is still not running properly, disconnect the suspect injector
and connect the injector circuit tester. Start the engine and run for A FEW SECONDS
ONLY. If the injector circuit is OK, then the tester will flash whilst the engine is
running. DO NOT RUN THE ENGINE FOR EXTENDED PERIODS WITH THE INJECTORS
DISCONNECTED AS SERIOUS DAMAGE TO THE CATALYTIC CONVERTERS WILL OCCUR.
ADAPTIVE 1 & ADAPTIVE 2
These numbers represent the percentage by which the ECU has adjusted the amount of
fuel being injected in order to achieve the correct mixture. There are adaptive
values for every combination of speed and load, which will change independently of
each other. If the engine is running correctly this percentage should be low. If it
is high ( >+/-20 percent) then a fault or maladjusted throttle pot should be
suspected.
IF A CAR HAS BEEN RUNNING BADLY WITH FAULTS PRESENT, THE ADAPTIVE MAPS
MUST BE RESET TO ZERO. This is done by selecting "ZERO ADAPTIVE MAPS" from
the ECU TOOLS menu.
Disconnecting the ECU does not erase its memory on 941 series ECUs!
IGNITION
Ignition timing is displayed in degrees before TDC. At idle, with coolant temp above
80 C , it should be between 17 & 22 degrees. If it is not, check all inputs for
correct readings, and check idle speed is set at 950 RPM.
FUEL PUMP
This denotes if the ECU has turned on the fuel pump. It does this by grounding pin 25
of the ECU, which completes the circuit for the fuel pump relay, thus turning the
relay on. If the pump appears turned on by the ECU but does not work, check that the
inertia switch has not tripped (the MIL lamp will turn on for 3 seconds when ignition
is turned on.) The inertia switch is located in the boot above the fuel tank. If the
fuel pump still doesn't work, check the relay No. 4 has a 12V supply to pins 85 & 30/51
if it does not check fuse 19.
NOTE! The fuel pump relay must be a twin make (brown) relay.
RAD FAN
This denotes if the ECU has turned on the radiator cooling fans. It does this when the
water temp input is above 92 C fan 1 ,94 C fan 2, or if a fault is present in the water
temp input. ECU pins 6 & 41 are grounded, to turn on the cooling fan relay(s). If the
fans appear turned on by the ECU but do not work, check the relay 1 & 7 has a 12V
supply to pins 85 & 30/51, if it does not, check fuse 1 , 3 and 20.
FAULTS, CURRENT & LOGGED - screen 2
This screen shows any input faults that the ECU has detected. Current faults are shown
at the top, logged faults below.
Logged faults are ones that have been detected in the past and may or may not still be
present. NOTE: FAULTS WILL BE LOGGED IF ANY SENSOR WIRES ARE
DISCONNECTED WHILST THE IGNITION IS TURNED ON!
Current faults will turn the MIL lamp on. Logged faults will not.
Observing the logged faults can be useful when tracing intermittent faults.
Logged faults can be removed by using the ECU Tools menu, or by connecting the fault
code diagnostic box to the diagnostic plug adjacent to the ECU connector, turning the
immobiliser off, and the ignition on. Then press and hold the black button on the
diagnostic box for at least three seconds.
THROTTLE 1 or 2 FLT
These faults are shown if the throttle pot readings are out of range.Thottle 1 is for
bank 1(cylinders 1357), throttle 2 is for bank 2(cylinders 2468) If a fault is detected
on one bank, then that input signal will be ignored, and both cylinders will be run
using the "good" throttle pot signal from the other bank.The MIL lamp will be turned
on.
bank 1 (cylinders 1357 ) , throttle 2 for bank 2 (cylinders 2468 ) If a fault is detected on one bank, then that input signal will be ignored, and both banks will be run using the "good" throttle pot signal from the other bank. The MIL lamp will be turned on.
Throttle pot faults
can be caused by: Water ingress into throttle pot, its connector or wiring.
(usually due to the use of a power washer)
Corrosion on throttle pot connectors.
(only use TVR gold plated connectors and throttle pots)
Mechanical damage to pot or wiring.
Throttle pot worn or "noisy"
WHEN A THROTTLE POTENTIOMETER IS REPLACED, IT MUST BE SEALED ONTO THE
THROTTLE BODY USING A SMALL AMOUNT OF SILICONE SEALANT TO PREVENT WATER
INGRESS. IT MUST THEN IMMEDIATELY BE SET CORRECTLY BEFORE THE SEALANT
SETS.
WATER FLT
This fault is shown if the water temperature signal is out of range.If it occurs,
a water temp of 95 C will be substituted, the cooling fans will be turned on to
prevent overheating, and the MIL lamp will be turned on.
Water fault can
be caused by: Water ingress into the water temperature sensor's connector
or wiring
Mechanical damage to sensor or wiring
Corrosion on sensor terminals or connector
Faulty sensor
AIR FLT
This fault is shown if the air temperature signal is out of range.If it occurs, an air
temp of 10 C will be substituted, and the MIL lamp will be turned on.
Air fault can
be caused by: Water ingress into the air temp sensor's connector or wiring
Mechanical damage to sensor or wiring
Corrosion on sensor terminals or connector
Faulty sensor
BARO FLT
This fault is shown if the barometric pressure signal is outside its normal range.
If it occurs, an atmospheric air pressure of 1000 mBAR will be substituted, and the
MIL lamp will be turned on.
Barometric fault
can be caused by: Kinked,broken or blocked barometric sensor pipe
Excessively clogged air filter
Mechanical damage to sensor or wiring
Corrosion on sensor terminals or connector
Faulty sensor
BAT FLT
This fault is shown if the battery voltage falls below 11 V,or rises above 17v whilst
engine speed is above 1500 RPM.
LAMBDA 1 & LAMBDA 2
These faults are shown if the lambda sensor signal rises above 1.7V.If it occurs the
MIL lamp will be turned on.
Lambda fault
can be caused by: Water ingress into the lambda sensor's connector or wiring.
Mechanical damage to sensor or wiring, causing a short
between the supply and signal wires.
Faulty sensor
AFR 1357 & 2468 FLT
These faults are shown if the adaptive values have reached their limits for bank 1357
or bank 2468, i.e. the system has attempted to adjust the mixture by an excessive
amount.
If either occur the MIL lamp will be turned on.
AFR fault can
be caused by: Excessive fuel pressure ( > 58 psi )
Air leaks in exhaust or inlet manifolds
Liquid fuel in purge system (check that the fuel tank breather
pipe is higher than the filler cap, and carbon can is empty of
liquid fuel)
Excessive purging due to overheating fuel (check fuel pipe routing
for heat pickup, insulate or reroute as required)
Incorrectly adjusted or faulty throttle potentiometers (check readings)
Faulty lambda sensors, or lambda sensor wiring
CRANK WIRING
This fault is shown if the crankshaft speed sensor is incorrectly wired up. Check polarity
and reconnect as shown in wiring diagram (black to pin 1 on sensor and to pin 2 on ECU,
white to pin 2 on sensor and to pin 12 on ECU )
CRANK SENSOR
This fault is shown if the crank sensor signal is poor.If it occurs the MIL lamp will NOT
be turned on. It may however flash as a poor signal is detected, depending on the severity
of the fault.
Crank sensor fault
can be caused by: Debris on end of crank sensor (remove and clean)
Water ingress into sensor connector or wiring Corrosion on sensor
terminals (clean or replace connector terminals using only gold plated
terminals)
Damaged trigger wheel on flywheel
Damaged crank sensor wiring (replace ONLY WITH SPECIAL CRANK
SENSOR WIRE)
SCREEN 3 - THROTTLE POT SETTING SCREEN
This screen shows the readings from throttle pot 1(at the top of the screen) and
throttle pot 2 (below) in large text.
This enables you to see the throttle pot readings from a large distance when adjusting
the throttle pots.
The throttle pot readings should be set to 15% WHEN THE THROTTLE BUTTERFLIES
ARE COMPLETELY CLOSED (i.e. with the THROTTLE STOP WOUND FULLY IN and with the
LINK ROD REMOVED)
When idling at 950 rpm at normal operating temperature the readings should be 18%+-2%
The throttle pot inputs are very sensitive and may be subject to a certain amount of
electrical noise (+/-2%) THIS IS NORMAL. However if this "noise" is excessive the
ECU may start to add acceleration fuel. If this occurs (observe dTHROTTLE box in the
AFR STATUS SCREEN) check that the HT leads are in good condition,FITTED TO ALL
THE PLUGS CORRECTLY and NOT TIE-WRAPPED TO THE MAIN ENGINE HARNESS.
Change the throttle pot if this fault persists.
AFR STATUS SCREEN
This screen shows in more detail the workings of the closed loop fuel system.
It should be viewed to establish that system is working correctly.
In order to work correctly, the catalytic converters must be supplied with exhaust gas
from chemically correct combustion. This means that the air fuel ratio must be
maintained at 14.6:1. This is done by using LAMBDA sensors in the exhaust gas to
measure whether combustion was rich or lean. When in a "rich" gas, the lambda sensor
will read appox 1-1.5V (provided it has warmed up) When in a "lean" gas, it will read
approx 0V. If it was rich the ECU reduces the amount of fuel to be injected at the
particular speed and load that the engine was at, when the exhaust gas being measured,
was created. If the mixture was lean, the ECU would increase the amount of fuel to be
injected. This adjustment is remembered as an adaptive value. There many adaptive
values created for all combinations of speed and load. Thus the ECU "retunes" the
engine throughout its life to maintain optimum performance.
Before lambda control can begin the lambda sensors must be allowed to warm up. This is
shown in the warm up timer box, and should last for approx. 30 seconds.
The engine temp must also be high enough to maintain combustion at an AFR of 14.6:1.
This is shown by the water temp box.
In order to accelerate cleanly without missing a richer mixture is required. This is
provided when rate of change of throttle position (dTHROTTLE) is detected. So, close
loop control is suspended whilst dTHROTTLE is present.
Very rapid changes in engine speed make reliable closed loop control impossible, so it
is also suspended under these conditions, as shown in the dSPEED box.
When running correctly, the lambda voltages should switch between 0 & 1V (approx.).
When under light load these voltages will stay predominantly lean (0V), with rich
spikes (1V).
As the load increases the engine should tend towards equal periods of running rich and
lean.
As the throttle position tends towards fully open, or the engine speed increases above
4000rpm closed loop control will be suspended in order to maximise performance.
This is shown in the LAMBDA CONTROL box.
The real-time display has 4 screens.
Use the PgUp and PgDn keys to toggle between them.
The first screen is the main screen and it is called the engine monitor screen
it shows all the main inputs and outputs of the ECU.(Press PgDn whilst in help
to find HELP for other real-time screens)
SCREEN 1 - ENGINE MONITOR SCREEN
INPUTS
ENGINE SPEED
Engine speed is displayed in RPM and it should correspond to actual engine speed.
Spurious or non-existent readings denote a faulty sensor or sensor wiring. Check
sensor for damage, metal debris on its end, corrosion or water in its terminals,
and correct polarity (see wiring diagram )
THROTTLE POSITION
Throttle position is displayed as a percentage of throttle potentiometer movement.
15% corresponds to a fully shut throttle, 94% to a fully open one. Idle position
is at approx. 19%. There are two throttle position sensors, one for each bank.
Page down to the third real-time screen to display throttle pot. readings only.
Throttle pot readings should be equal on both banks to within a few percent, and
must not fluctuate more than 3%. The readings should increase smoothly with
increasing throttle travel and remain approximately equal on both banks. If the
ECU detects a fault with one of the throttle pot readings it will substitute the
value from the other throttle pot, so they will both display EXACTLY THE SAME
READING.
AIR TEMP
Air temperature is measured by the sensor by the side of the air filter. If the
ECU detects a fault with this reading it will substitute a value of 10 degrees C.
WATER TEMP
Water temperature is measured by the sensor in the metal water pipe underneath the
trim panel in the front of the engine bay.If the ECU detects a fault with this
reading it will substitute a value of 95 degrees C. The engine cooling fans are
controlled by this temperature reading, and are turned on at 92 deg C, off at
88 deg C. Therefore under fault conditions the cooling fans will be turned on.
BATTERY VOLTAGE
Battery voltage is displayed in volts. It should normally read between 12.0 & 13.8V
There is no default value.
BAROMETRIC PRESSURE
Barometric pressure is measured from the left hand air box and is displayed in mBAR.
It should correspond to the air pressure as measured on a barometer. If the ECU
detects a fault with this reading it will substitute a value of 1000 mBAR. The
pressure sensor is mounted inside the car to protect it from excessive heat. If
incorrectreadings are displayed, check the pipe between the sensor and airbox for
blockages or leaks.
LAMBDA 1 & LAMBDA 2
Lambda 1&2 show the signals from the lambda sensors on each bank. After starting the
sensors will take at least 30 seconds to warm up, before they will read correctly .
Once warmed up, the lambda signals should switch between approx. 0 & 1-1.5 volts.
0 volts shows that the fuel mixture is lean, 1 volt shows that the mixture is rich.
The rate of switching will alter with engine speed, and the percentage of time spent
rich relative to lean will alter with engine load. If reading is a CONSTANT 0 V, check
sensor for proper connection, and sensor heater wires for continuity (6 ohms between
white red wires)
NOTE: Lambda sensors are supplied with 12V on the red wires ONLY WHEN THE
FUELPUMP IS RUNNING, the WHITE wire is earth and BLACK the signal.
OUTPUTS
FUEL 1 & FUEL 2
Fuel injection time is displayed for each bank. When water temp >80 C at idle it
should be between 2.2 & 2.4 ms. Higher readings than this could indicate misfiring
due to fouled plugs, incorrectly balanced throttle assemblies, or faulty lambda
sensor readings. Check primary exhaust pipe temperatures to detect poorly running
cylinders, and check cylinder airflow with syncrometer to detect poor balance. If
all cylinders are running correctly check lambda sensors as above, replace if
faulty. If a cylinder is still not running properly, disconnect the suspect injector
and connect the injector circuit tester. Start the engine and run for A FEW SECONDS
ONLY. If the injector circuit is OK, then the tester will flash whilst the engine is
running. DO NOT RUN THE ENGINE FOR EXTENDED PERIODS WITH THE INJECTORS
DISCONNECTED AS SERIOUS DAMAGE TO THE CATALYTIC CONVERTERS WILL OCCUR.
ADAPTIVE 1 & ADAPTIVE 2
These numbers represent the percentage by which the ECU has adjusted the amount of
fuel being injected in order to achieve the correct mixture. There are adaptive
values for every combination of speed and load, which will change independently of
each other. If the engine is running correctly this percentage should be low. If it
is high ( >+/-20 percent) then a fault or maladjusted throttle pot should be
suspected.
IF A CAR HAS BEEN RUNNING BADLY WITH FAULTS PRESENT, THE ADAPTIVE MAPS
MUST BE RESET TO ZERO. This is done by selecting "ZERO ADAPTIVE MAPS" from
the ECU TOOLS menu.
Disconnecting the ECU does not erase its memory on 941 series ECUs!
IGNITION
Ignition timing is displayed in degrees before TDC. At idle, with coolant temp above
80 C , it should be between 17 & 22 degrees. If it is not, check all inputs for
correct readings, and check idle speed is set at 950 RPM.
FUEL PUMP
This denotes if the ECU has turned on the fuel pump. It does this by grounding pin 25
of the ECU, which completes the circuit for the fuel pump relay, thus turning the
relay on. If the pump appears turned on by the ECU but does not work, check that the
inertia switch has not tripped (the MIL lamp will turn on for 3 seconds when ignition
is turned on.) The inertia switch is located in the boot above the fuel tank. If the
fuel pump still doesn't work, check the relay No. 4 has a 12V supply to pins 85 & 30/51
if it does not check fuse 19.
NOTE! The fuel pump relay must be a twin make (brown) relay.
RAD FAN
This denotes if the ECU has turned on the radiator cooling fans. It does this when the
water temp input is above 92 C fan 1 ,94 C fan 2, or if a fault is present in the water
temp input. ECU pins 6 & 41 are grounded, to turn on the cooling fan relay(s). If the
fans appear turned on by the ECU but do not work, check the relay 1 & 7 has a 12V
supply to pins 85 & 30/51, if it does not, check fuse 1 , 3 and 20.
FAULTS, CURRENT & LOGGED - screen 2
This screen shows any input faults that the ECU has detected. Current faults are shown
at the top, logged faults below.
Logged faults are ones that have been detected in the past and may or may not still be
present. NOTE: FAULTS WILL BE LOGGED IF ANY SENSOR WIRES ARE
DISCONNECTED WHILST THE IGNITION IS TURNED ON!
Current faults will turn the MIL lamp on. Logged faults will not.
Observing the logged faults can be useful when tracing intermittent faults.
Logged faults can be removed by using the ECU Tools menu, or by connecting the fault
code diagnostic box to the diagnostic plug adjacent to the ECU connector, turning the
immobiliser off, and the ignition on. Then press and hold the black button on the
diagnostic box for at least three seconds.
THROTTLE 1 or 2 FLT
These faults are shown if the throttle pot readings are out of range.Thottle 1 is for
bank 1(cylinders 1357), throttle 2 is for bank 2(cylinders 2468) If a fault is detected
on one bank, then that input signal will be ignored, and both cylinders will be run
using the "good" throttle pot signal from the other bank.The MIL lamp will be turned
on.
bank 1 (cylinders 1357 ) , throttle 2 for bank 2 (cylinders 2468 ) If a fault is detected on one bank, then that input signal will be ignored, and both banks will be run using the "good" throttle pot signal from the other bank. The MIL lamp will be turned on.
Throttle pot faults
can be caused by: Water ingress into throttle pot, its connector or wiring.
(usually due to the use of a power washer)
Corrosion on throttle pot connectors.
(only use TVR gold plated connectors and throttle pots)
Mechanical damage to pot or wiring.
Throttle pot worn or "noisy"
WHEN A THROTTLE POTENTIOMETER IS REPLACED, IT MUST BE SEALED ONTO THE
THROTTLE BODY USING A SMALL AMOUNT OF SILICONE SEALANT TO PREVENT WATER
INGRESS. IT MUST THEN IMMEDIATELY BE SET CORRECTLY BEFORE THE SEALANT
SETS.
WATER FLT
This fault is shown if the water temperature signal is out of range.If it occurs,
a water temp of 95 C will be substituted, the cooling fans will be turned on to
prevent overheating, and the MIL lamp will be turned on.
Water fault can
be caused by: Water ingress into the water temperature sensor's connector
or wiring
Mechanical damage to sensor or wiring
Corrosion on sensor terminals or connector
Faulty sensor
AIR FLT
This fault is shown if the air temperature signal is out of range.If it occurs, an air
temp of 10 C will be substituted, and the MIL lamp will be turned on.
Air fault can
be caused by: Water ingress into the air temp sensor's connector or wiring
Mechanical damage to sensor or wiring
Corrosion on sensor terminals or connector
Faulty sensor
BARO FLT
This fault is shown if the barometric pressure signal is outside its normal range.
If it occurs, an atmospheric air pressure of 1000 mBAR will be substituted, and the
MIL lamp will be turned on.
Barometric fault
can be caused by: Kinked,broken or blocked barometric sensor pipe
Excessively clogged air filter
Mechanical damage to sensor or wiring
Corrosion on sensor terminals or connector
Faulty sensor
BAT FLT
This fault is shown if the battery voltage falls below 11 V,or rises above 17v whilst
engine speed is above 1500 RPM.
LAMBDA 1 & LAMBDA 2
These faults are shown if the lambda sensor signal rises above 1.7V.If it occurs the
MIL lamp will be turned on.
Lambda fault
can be caused by: Water ingress into the lambda sensor's connector or wiring.
Mechanical damage to sensor or wiring, causing a short
between the supply and signal wires.
Faulty sensor
AFR 1357 & 2468 FLT
These faults are shown if the adaptive values have reached their limits for bank 1357
or bank 2468, i.e. the system has attempted to adjust the mixture by an excessive
amount.
If either occur the MIL lamp will be turned on.
AFR fault can
be caused by: Excessive fuel pressure ( > 58 psi )
Air leaks in exhaust or inlet manifolds
Liquid fuel in purge system (check that the fuel tank breather
pipe is higher than the filler cap, and carbon can is empty of
liquid fuel)
Excessive purging due to overheating fuel (check fuel pipe routing
for heat pickup, insulate or reroute as required)
Incorrectly adjusted or faulty throttle potentiometers (check readings)
Faulty lambda sensors, or lambda sensor wiring
CRANK WIRING
This fault is shown if the crankshaft speed sensor is incorrectly wired up. Check polarity
and reconnect as shown in wiring diagram (black to pin 1 on sensor and to pin 2 on ECU,
white to pin 2 on sensor and to pin 12 on ECU )
CRANK SENSOR
This fault is shown if the crank sensor signal is poor.If it occurs the MIL lamp will NOT
be turned on. It may however flash as a poor signal is detected, depending on the severity
of the fault.
Crank sensor fault
can be caused by: Debris on end of crank sensor (remove and clean)
Water ingress into sensor connector or wiring Corrosion on sensor
terminals (clean or replace connector terminals using only gold plated
terminals)
Damaged trigger wheel on flywheel
Damaged crank sensor wiring (replace ONLY WITH SPECIAL CRANK
SENSOR WIRE)
SCREEN 3 - THROTTLE POT SETTING SCREEN
This screen shows the readings from throttle pot 1(at the top of the screen) and
throttle pot 2 (below) in large text.
This enables you to see the throttle pot readings from a large distance when adjusting
the throttle pots.
The throttle pot readings should be set to 15% WHEN THE THROTTLE BUTTERFLIES
ARE COMPLETELY CLOSED (i.e. with the THROTTLE STOP WOUND FULLY IN and with the
LINK ROD REMOVED)
When idling at 950 rpm at normal operating temperature the readings should be 18%+-2%
The throttle pot inputs are very sensitive and may be subject to a certain amount of
electrical noise (+/-2%) THIS IS NORMAL. However if this "noise" is excessive the
ECU may start to add acceleration fuel. If this occurs (observe dTHROTTLE box in the
AFR STATUS SCREEN) check that the HT leads are in good condition,FITTED TO ALL
THE PLUGS CORRECTLY and NOT TIE-WRAPPED TO THE MAIN ENGINE HARNESS.
Change the throttle pot if this fault persists.
AFR STATUS SCREEN
This screen shows in more detail the workings of the closed loop fuel system.
It should be viewed to establish that system is working correctly.
In order to work correctly, the catalytic converters must be supplied with exhaust gas
from chemically correct combustion. This means that the air fuel ratio must be
maintained at 14.6:1. This is done by using LAMBDA sensors in the exhaust gas to
measure whether combustion was rich or lean. When in a "rich" gas, the lambda sensor
will read appox 1-1.5V (provided it has warmed up) When in a "lean" gas, it will read
approx 0V. If it was rich the ECU reduces the amount of fuel to be injected at the
particular speed and load that the engine was at, when the exhaust gas being measured,
was created. If the mixture was lean, the ECU would increase the amount of fuel to be
injected. This adjustment is remembered as an adaptive value. There many adaptive
values created for all combinations of speed and load. Thus the ECU "retunes" the
engine throughout its life to maintain optimum performance.
Before lambda control can begin the lambda sensors must be allowed to warm up. This is
shown in the warm up timer box, and should last for approx. 30 seconds.
The engine temp must also be high enough to maintain combustion at an AFR of 14.6:1.
This is shown by the water temp box.
In order to accelerate cleanly without missing a richer mixture is required. This is
provided when rate of change of throttle position (dTHROTTLE) is detected. So, close
loop control is suspended whilst dTHROTTLE is present.
Very rapid changes in engine speed make reliable closed loop control impossible, so it
is also suspended under these conditions, as shown in the dSPEED box.
When running correctly, the lambda voltages should switch between 0 & 1V (approx.).
When under light load these voltages will stay predominantly lean (0V), with rich
spikes (1V).
As the load increases the engine should tend towards equal periods of running rich and
lean.
As the throttle position tends towards fully open, or the engine speed increases above
4000rpm closed loop control will be suspended in order to maximise performance.
This is shown in the LAMBDA CONTROL box.
There's also the stuff here on using the software on a SP6 engine, but the explanations are good:
http://www.thetvrsite.com/ecu-diagnostic-software/...
http://www.thetvrsite.com/ecu-diagnostic-software/...
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