Drivability

OBD 2

1996 and newer Detect components degradation alert driver of needed emission repair.

OBD-II has been on all passenger vehicles in the United States since

1996v

When testing an EGR system for proper operation using a vacuum gauge, how much should the vacuum drop when the EGR is commanded on by a scan tool?

6 to 8 in. Hg

A P0401 DTC (exhaust gas recirculation flow insufficient) is being discussed. Technician A says that a defective EGR valve could be the cause. Technician B says that clogged EGR passages could be the cause. Which technician is correct?

Both

OBD-II regulations require that the EGR system be tested. Technician A says that the PCM can monitor the commanded position of the EGR valve to determine if it is functioning correctly. Technician B says that the PCM can open the EGR valve and monitors for a change in the MAP sensor or oxygen sensor reading to detect if the system is functioning correctly. Which technician is correct?

Both

Technician A states that OBD II generic codes are generated when monitors run. Technician B states that DTCs can be "decoded" to reveal the system fault. Who is correct?

Both Tech A and Tech B

Technician A states that standardized communications protocol will allow any OBD II scanner to retrieve DTC's. Technician B states that the generic protocol will generate limited scanner information that can be used to pass or fail an emission test. Who is correct?

Both Tech A and Tech B

Technician A states that the enabling criteria are the set of conditions required to get the monitor to run. Technician B states that a DTC can only be set if the monitor responsible for the DTC runs.

Bothh Tech A and Tech B

Exhaust gas recirculation (EGR) is generally not needed under all the following conditions

Cruise speed

What is an OBD II drive cycle?

Driving conditions designed to enable a monitor to run to completion

none continuous

Evap 02 emmisons monitors

The computer will automatically clear a DTC if there are no additional detected faults after

Forty consecutive warm-up cycles

Which is a continuous monitor?

Fuel system monitor

DTC P0302 is a

Generic DTC

What causes the nitrogen and the oxygen in the air to combine and form NOx?

Heat above 2500 degrees F (1370 degree C)

EGR is used to control which exhaust emission?

Oxides of nitrogen (NOx)

By looking at the way diagnostic trouble codes are formatted, which DTC could indicate that the gas cap is loose or defective?

P0442

A typical EGR pintle-position sensor is what type of sensor?

Potentiometer

Clogged vent

Problem refueling run rich

An EGR valve that is partially stuck open would most likely cause what condition?

Rough idle/stalling

The PCM determines catalyst efficiency by looking at what two sensor inputs?

S1 O2S and S2 O2S

Technician A says that a low-restriction exhaust system could prevent a back pressure-type vacuum-controlled EGR valve from opening correctly. Technician B says restricted exhaust can cause the EGR valve position sensor to fail. Which technician is correct?

Tech B

Technician A states that the MIL will be illuminated when the PCM runs a monitor. Technician B states that monitors must run before any DTC's will be set. Who is correct?

Tech B

Technician A states that the enabling criteria should be accomplished during normal driving. Technician B states that individual pieces of the enabling criteria must be followed in sequence or the monitor may not run. Who is correct?

Tech B

Abilities of OBD 2

Test outputs of relay vvt injectors solenoid

A pending code is set when a fault is detected on _______.

The first fault of a two-trip failure

It takes at least two drive cycles to turn off the MIL

True

An ignition misfire or fuel mixture problem is an example of what type of DTC?

Type A

A freeze-frame is generated on an OBD-II vehicle __________.

When a type A or B diagnostice trouble code is set

check engine light is on. This indicates that

a monitor has set a DTC

A PID is

a single line of data viewed on a scanner

The sequence of driving conditions to generate DTCs usually is

called the enabling criteria

Pcm

control vaccum to egr

2 types of EGR

external and natural

Purge no working

fuel trim goes negative no fuel trim change no pressure change

The comprehensive component monitor checks computer-controlled devices for

functionality

Egr benefits

helps fuel economy prevent detonation

A generic DTC

is the same for all manufacturers

continous monitors

misfire fuel trim pcv thermostat

What is the FTP standard for tailpipe emissions?

not to exceed 1.5 times

4 types of evap system

vaccum pressure esim natural vacuum

Controlling Nox without EGR

valve overlap vvt

vacuum EGR

works on back pressure > as we increase engine load back pressure increases.