Kia Carens. Manual - part 75

Transaxle range switch(A/T) Detects shift lever position and sends to ECM

1. For idle speed control
2. Load/no/load
determination

OBD-II overview

• Primary emission control system/components
• Heated oxygen sensors (includes heater)
• Catalyst
• Fuel system
• Evaporative emission system
• Misfire
• Comprehensive components (input and output)

Heated oxygen sensor monitoring

System description

Monitoring process

• Heater voltage and current.
• Period of front HO2S reaction
• Other parameter (Tv) to monitor sensor aging.

Heater voltage and current

The voltage readings taken from the HO2 Sensor are very temperature sensitive and are not particularly accurate below
300C. For this reason, heating of the HO2 sensor is necessary to allow the engine crontroller to shift to closed loop
control as soon as possible. The heating element used to heat the HO2 Sensor must be tested to ensure that it is
heatingthe sensor properly.

Period of front HO2 reaction

The ECM is supplied with information regarding the oxygen content of the exhaust gases by the front HO2S. The signal
isused to compute the injection period. The front HO2S monitors the contaminated exhaust gases. This, in time, causes
agingof the device and a change in the signal. To monitor the front HO2S responsiveness, the response period of the
upstreamoxygen sensor signal is compared with a lower and upper threshold. This comparison is done in an applicable
range of engine speed and load with the engine at operating temperature. If the actual mean value of the period is
outsideof the lower and upper period thresholds the diagnostic trouble code is set.

Other parameter (Tv) to monitor sensor aging

The sensor aging is monitored by comparing the front and rear HO2S and also using the correction value (Tv) which
determines the mean value of the lean/rich shift necessary for optimal air/fuel ratio-control. With the help of this
information, the ECM can make allowance for aging of the front HO2S in its injection period calculations. When the
parameter-Tv is above or below the specific limits, the ECM will set the diagnostic trouble code HO2S Slow Response by
aging.

MIL illumination

If any fault relating to HO2S is detected, then the MIL is only turned ON if the same fault is again detected during a
second drive cycle.

Three way catalytic converter (TWC) monitoring (System description)

Fuel system monitoring (System description)

• Engine load (MAF sensor)
• Engine Speed (SGT)
• Short fuel trim correction factor
• Long fuel trim correction factor

Fuel trim is monitored to meet the OBD-II requirements

1. Short fuel trim (FT)

Short FT is a temporary correction to fuel delivery which changes with every cycle of the front Heated Oxygen Sensor.
Under normal conditions, it fluctuates rapidly around its ideal value of 0% correction and is set to 0% during open loop
operation.
Short FT is a parameter of the OBD-II serial data stream and can be displayed by a scan tool. The normal range of
shortFT is ±25%, but under normal operating conditions it rarely goes beyond ±10%. Short FT responds to changes in
front HO2S output. If basic injection duration results in a lean air/fuel ratio, Short FT responds with positive corrections
(+1% to +25%) to add fuel and enrich the mixture. If basic injection is too rich, Short FT responds with negative
corrections (-1% to -25%) to subtract fuel and lean the mixture.

2. Long Fuel Trim

Long FT is a data parameter on the OBD-II data streams. It is a more permanent correction to fuel delivery because it
ispart of the basic injection duration calculation. Long FT changes slowly, in response to Short FT. It's normal rangeis
±25%, positive values indicating rich correction and negative values indicating lean correction.

Unlike Short FT which affects injection duration calculation in closed loop only, the Long FT correction factor affectsthe
basic injection duration calculation in open and closed loop. Because Long FT is stored in a non-volatile RAM andis
not erased when the ignition is switched OFF, the fuel system is able to correct for variances in engine and fuel
conditions even during warm-up and wide open throttle conditions.

Monitoring process

MIL illumination

Evaporative emission controls (Evaporative Control System)

1. Fuel tank

The fuel tank is located under the rear of the vehicle. The fuel pump, fuel level sending unit and fuel tank pressure
sensor are installed on the upper part of the fuel tank.

2. Fuel filler cap

A ratchet tightening device on the threaded fuel filler cap reduces the chances of incorrect installation, which would
prevent sealing fuel vapors. After the gasket on the fuel filler cap and the fill neck flange contact each other, the
ratchet produces a loud clicking noise indicating the seal has been set

3. Evaporative emissions canister

A maintenance free, EVAP canister is used on the Rio located under the right side of the vehicle near the fuel tank.
TheEVAP canister is filled with granules of an activated carbon mixture. Fuel vapors enter into the EVAP canister are
absorbed by the charcoal granules. Fuel tank pressure vents into the EVAP canister and are temporarily held in the
canister until they can be drawn into the intake manifold.

4. Purge solenoid valve

This valve is actuated by the purge control signal from the ECM and controls fuel vapor from the EVAP Canister to the
intake manifold.

Misfire monitoring (System description)

Monitoring conditions

Monitoring process

MIL illumination

The MIL flashes while a catalyst damaging misfire is being detected.

COMPREHENSIVE COMPONENTS MONITORING

Any input or output components that can affect emissions or any input or output component used to monitor any other
monitored component/system is monitored.
The lack of circuit continuity any rationality, and out-ofrange values to ensure proper operation of the input devices, are
monitored for proper response to ECM commands.

  2001 > 1.8L DOHC >

 

Components

Underhood emission control components