Mercury EFI
If the sensor in a pull up circuit is removed from the harness with the key on, the pcm will report _________ at the analog to digital convertor for that sensors circuit.
5V
An engine seems to be idling fine, but the G3 data shows the IAC is being commanded to be a completely closed. What problem could cause this?
Air from somewhere
When testing a battery with the MidTronics Tester, please list the 4 steps you must take in order to obtain an accurate result.
Connect to batt post disconnect from all other batt test fully charged batt remove surface charge
Mercury temp sensors ___________ in resistance as they _____________ A decrease, cool down B increase, warm up C decrease, warm up D none of the above
Decrease, warm up
Sensors that monitor temp such as the ECT and IAT/MAT are primarily used by the ECM/PCM to modify:
Fuel
A pre catalyst oxygen sensor. has become contaminated and is sluggish (it is responding slowly). what will most likely be the result? A fuel economy will drop B fuel economy will stay the same C fuel economy will increase D it doesn't matter because the PCM uses the post O2 sensors input to adjust fuel delivery
Fuel economy will drop
In most every instance, the PCM controls actuators. by controlling the A 12V power B Ground C Pulse Width D frequency
Ground
It does not matter if an engine uses one or multiple ground ignition coils. Mercury ignition coils receive power and ___________, and fire when the ___________ is removed by either a coil controller or the the PCM/ECM
Ground
When an engine is accelerated, info from the ___________ sensor is used by the ECM/PCM to increase the fuel injector pulse width to add additional fuel needed for the acceleration event ( acts like an accelerator pump input)
TPS (throttle position sensor)
Mercury 3 wire circuits are: A all pull up circuits B all pull down circuits C can be pull up or pull down D none of the above
can be either pull up or pull down
input from the __________ & _____________ sensor is needed in order for many PCMs to. determine what stroke the engine is on (engine phase). A cps, 02 B cmp, mapt C cmp, cps D cps, map, iat/mat (if equiped)
cmp, cps
Narrow band oxgen sensors cannot provide accurate feedback to the ECM/PCM under all operating conditions A true B false
true
If the sensor in a pull down circuit is removed from the harness with the key on, the pcm will report _________ at the analog to digital convertor for that sensors circuit.
0v
A circuit has a high fault being reported. The counts might be in the range of: A 200-580 B 600-800 C 1017-1023 D 1023-1203
1017-1023
A fast way to identify a narrow band from a wind band oxygen sensor is to count the wires. A Merc narrow band sensor has ____________ wires, a Mercury wide band sensor has _____________ wires.
4, 5
What number in the in the Equivilence Ratio/PHI Table represent a richer air/fuel ratio than the stoichiometric ratio? A Any number lower than 1 B 1.00 C Any number greater than 1
Any number greater than 1
When a manifold reference line is connected to the reference port of the fuel pressure regulator, fuel pressure will vary with manifold pressure. Fuel pressure will ___________ as intake pressure drops and _____________ as manifold pressure rises.
Drop, Rise
An engine experienced a failed head gasket and fresh water (closed) coolant was sucked into the cylinder and went out the exhaust. What do you think might happen to the O2 sensor in the corresponding exhaust manifold?
Failure
The analog to digital converter: A How the ECM converts voltages into computer language it can work with internally and. where counts are calculated B Necessary only in DTS applications C able to. easily and inexpensively be replaced when it fails D none of the above
How the ECM converts voltages into computer language it can work with internally and. where counts are calculated
Why can a short or open on a single wire effect multiple circuits?
If they share the same common ground
A MAP sensor circuit sensor has failed in range. The MAP sensor is reporting very low load while the engine is running under a high load. The engine will most likely: A run just fine, the ECM/PCM will know how to adjust B Run incorrectly because it is receiving incorrect fuel and timing C run poorly only when it is initially started and warming up D none of the above
Run incorrectly because it is receiving incorrect fuel and timing
The voltage or counts reported on the scan tool are calculated and sent by: A the sense lead in the harness B the ground lead in the harness C the analog to digital convertor (ADC) inside PCM D the sensor
The ADC
The insulation of a wire has been pierced and internal corrosion has begun to create resistance. The wire is part of a sensor circuit. What will most likely happen? A The PCM will begin to get readings from the circuit that are inaccurate due to the resistance B nothing will happen. Every time the system. is powered up, the sensors are reset to a starting point so it wont matter C The sensor will fail D None of the above
The PCM will begin to get readings from the circuit that are inaccurate due to the resistance
The term Stoichiometric always means: A 14.7:1 B The air/fuel ratio where best power is produced C The air/fuel ratio where complete combustion occurs and emissions are cleanest D The air/fuel ratio that burns the coolest
The air/fuel ratio where complete combustion and emissions are cleanest
As an engine has no faults and seems to labor a little when starting cold. Also, the cold idle RPM is slightly below spec. As it warms up, it idles a little higher. than spec. The tech should: A Replace the CTC sensor - it's probably bad B Verify IAC function C graph the TP data and look for fluctuations D nothing - it idles ok when it warms up so its non-issue
Verify IAC function
Gas burns at a constant rate. Because of this, spark timing must be _________ as. engine RPM increases.
advanced
An IAT Circuit Low is being reported. The: A signal lead circuit might. be shorted to engine block ground B sensor may have failed internally C. IAT wires in the harness. might be pinched together and. shorted D All of. the above
all of the above
An engine has low fuel pressure. This could be caused by: A failed pressure regulator B Failing high pressure fuel pump C Clogged fuel filter or pinched/restricted fuel line D All of the above
all of the above
As engine load increases toward maximum, spark timing is reduced. This means it occurs: A further before TDC B closer to TDC
closer to tdc
An engine is started cold and the ECM begins monitoring the. coolant temp. sitting at idle, the fuel injector pulse width will _________ as it warms up to operating temp. A stay the same B decrease C increase
decrease
Anything that makes it harder for the spark to jump the gap at the sparks lowers the kV readings, and anything. that makes it easier for the sparks to jump the gap raise the kV. A true B false
false
Sensors make decisions. A true B false
false
Wide band oxygen sensors are used after the catalyst. A true B false
false
A tech is monitoring the data on an emission controlled engine. He disconnects an IAT sensor and a fault is reported by the PCM. He reconnects the sensor and the fault remains active. He turns the key off and back on. The fault still remains active. This is: A normal, the tech probably bent a pin and the fault is probably real B normal, emission related faults stay active until they are repaired and either manually cleared or the PCM sees enough start and run cycles to clear by self C abnormal, the PCM has an internal processor failure D abnormal, the fault should have immediately gone inactive - the sensor has most likely failed
normal, emission related faults stay active until they are repaired and either manually cleared or the PCM sees enough start and run cycles to clear by self
What will happen if the gap between the tip of the CPS or the CMP and the corresponding reluctor teeth is too large? A the sensor will trigger, but will be delayed by approximately a tooth B the sensor will become inaccurate because it will "see" too many teeth at the same time due to being spaced farther back C the sensor will not be triggered D nothing - the air gap can be any distance from the reluctor teeth - the sensor just has to be spaced far enough away from the reluctor teeth not to touch them
nothing - the air gap can be any distance from the reluctor teeth - the sensor just has to be spaced far enough away from the reluctor teeth not to touch them
A power 1 low fault is being reported and numerous sensor circuits have faults A all the sensors should be replaced B power 1 is most likely shorted to ground. unplugging the sensors one at a time while monitoring the power 1 fault might locate a faulty sensor C every wire should be checked for continuity from the harness connector to the PCM D none of the above
power 1 is most likely shorted to ground. unplugging the sensors one at a time while monitoring the power 1 fault might locate a faulty sensor
When measuring voltage on and Mercury 2 wire temp circuit the voltage A drops to 0v when the circuit is open, and rises to reference voltage when the sense lead is to ground B rises to reference voltage when the circuit is open, and drops to 0v when the sense lead is shorted to ground C drops to 0v when the circuit is either shorted or opened D rises to reference voltage when the circuit is either shorted or opened
rises to reference voltage when the circuit is open, and drops to 0v when the sense lead is shorted to ground
The ECM/PCM sends a 5v reference voltage to many _______________ and receive a signal/sense voltage back.
sensors
The fuel rail connects the all of the fuel injectors to a common fuel ___________ at a common fuel pressure.
supply
A noid light has been installed in the place of a fuel injector on an engine that runs well except for a dead on one miss cylinder. The cylinder appears to be fuel starved/dry. The noid light blinks when the engine is cranked or when it is running. This tells you: A the injector is good- check the wiring B the injector is most likely the issue because if the light blinks, the wirings good C both the injector and the wiring are bad
the injector is most likely the issue because if the light blinks, the wire is good
On the low circuit side of a relay, the control coil is activated and the contact points are closing - you can hear the click each time the circuit is turned off and on. The high current side of the relay, 12 v going in and 0v are being measured on the output leg when the relay is activated (points are closed). A this is normal and nothing needs to. be done B this is abnormal and the harness is most likely the cause C this is abnormal and the relay is most likely the cause D none of the above
the is abnormal and the relay is most likely the cause
A three wire circuit high fault. when the sensor is removed the does not change A the sensor might still be the problem. this may be a pull up circuit and removing the sensor. should result in circuit high fault B the sensor is ok and the problem is in the wiring or PCM C the sensor is the problem - replace the sensor D none of the above
the sensor might still be the problem. this may be a pull up circuit and removing the sensor. should result in circuit high fault
When the harness connector of an engine equipped with an Electronic throttle body is disconnected, a circuit high fault is generated for one of the TP sensors and a circuit low is generated for the other. When the voltages are measured at the signal/sense leads in the harness, both read 0v. this is because: A one of the circuits is shorted to power and reading. high B one of the circuits is open and reading low -they should both be reading high C they are both pull down circuits and should be readings are normal. the calibrations inverts one of the readings D the service tool. has a problem in it
they are both pull down circuits and should be readings are normal. the calibrations inverts one of the readings
A bad battery, a battery that does not meet min. specs or poor battery connections can be cause of intermittent fault or false faults. A. true B false
true
Wasted. spark ignition coils fire. both ports at nearly the same time and. are called wasted. spark because one plug fires on the exhaust stoke A true B false
true
When faults appear to be intermittent, one technique to try and recreate them is by wiggling the harness and connectors A true B false
true
kV meter report the firing voltage required in each cylinder. Using a kV meter can quickly help you identify suspect cylinders. A true B false
true
The pre catalyst oxygen. sensor is: A used by the PCM to monitor the health of the catalyst B used by the PCM to adjust fuel delivery for injection events C considered an actuator D none of the above
used by. the PCM to adjust fuel delivery for injection events
A crank / no start is occurring on an engine. the engine makes all the normal clicks and sounds it should when the key is turned on. there are no engine faults. what data item should the tech pay attention to in G3 when cranking engine? A MAP sensor reading B IAT sensor reading C CPS reading D CMP sensor reading
CPS reading
What three sensors give the ECM/PCM the information necessary to perform the Speed Density? (some earlier non-current systems may only use two of them and a default value for the third) A CPS, CMP, IAT/MAT B CPS, MAP, IAT/MAT C ECT,TP, IAT/MAT
CPS, MAP, IAT/MAP
Speed Density electronic fuel injection systems ___________ the actual oxygen content in the air, they do truly measure it.
Calculate
The ECM/PCM only understands ____________. It does not understand temp. pressure or RPM
Counts
Mercury two wire circuits are: A pulse width modulated circuits B pull down circuits C pull up circuits D none of the above
Pull up circuits
When we discuss airfuel ratios, they are measured in parts of air to parts of fuel by: A volume B Weight C Cubits D Stones
Weight
Actuators on the the ____________ side of the ECM/PCM.
Output
E15 has been installed in an open loop EFI system. The engine will run: A Too rich B Too lean C The same D It won't run at all- it will most likely result in a crank/no start condition
Too lean
A circuit can show 12v on a DVOM and fail to light a test light. This is a normal condition in some circuits. A true B false
True
A leak down test will help determine where compression is being lost. A true B false
True
Closed loop EFI systems can run in open loop mode all the time. A true B false
True
It is normal for a catalyst to have a crown after it has been in service and has heat cycled many times. A true B false
True
Why must we never disconnect a spark plug wire from the cylinder of a. running. catalyst equipped engine?
Will damage catalyst.
A fault means: A a problem with a sensor has been detected B a circuit is reporting a value that is out of range C the sensor needs to be replaced D there is a short in the wiring
a circuit is reporting a value out of range
Numerous faults are being reported. The faults affect two and three wire sensors. A all of the sensors should be replaced B a common power wire is most likely at fault C a common ground wire is most likely at fault D None of the above
a common ground wire is most likely at fault