P2190
DTC P2188 SYSTEM TOO RICH AT IDLE (BANK 1)DTC P2190 SYSTEM TOO RICH AT IDLE (BANK 2)
GENERAL DESCRIPTION
Air-fuel feed back control is the modulation which increases or decreases fuel injection quantity as determining exhaust gas rich or lean with HO2S adjust combustion is done at ideal air-fuel ratio to so as to raise the efficiency of catalytic converter. Generally, NOx increases at lean combustion while CO, HC increases in rich combustion. Thus, in order to purge all of these gases with catalytic converter, air-fuel ratio should be nearly at the ideal ratio. However the range in which all gases purified successfully is too narrow, it is impossible to meet ideal range with open loop control, therefore feed back control using HO2S is required. HO2S output signal changes rapidly near ideal air-fuel ratio and this characteristic is used at feed back control, comparing HO2S output signal and reference value, PCM increases fuel injection quantity at lean condition and decreases at rich condition. As deterioration of engine, due to the characteristic changes of many components of intake and fuel line or inevitable tolerance of components at production process, achieving ideal air-fuel ratio is almost impossible with the fixed fuel injection duration. Regarding the change of cross section by clogged injector, feed back correction is performed yet, it cannot cover all the ranges. It means if the correction range is massively separated from the ideal value or if the mean of feed back control range too inclines to lean or rich condition, feed back correction does not work efficiently. Therefore processing correction value throughout long time statistically during driving, PCM controls fuel injection duration as fitting the mean to be the ideal air-fuel ratio value. Through adaptive control, accuracy of the control could be improved and the value of adaptive control varies continuously during driving and is always up-dated.
DTC DESCRIPTION
Checking air-fuel ratio correction value every 0.75 sec. at idle, if the value within the detecting condition for more than 0.3 sec., PCM sets P2188/P2190. MIL (Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition:
MONITOR SCANTOOL DATA
1. Connect scantool to DLC (Data Link Connector)
2. Warm up the engine to normal operating temperature.
3. Monitor sensors related to fuel trim (Ex. HO2S, MAFS, MAPS, TPS, MAPS, TPS, ECTS, PCSV, lnjectors etc.) with scantool
4. Are those parameters displayed correctly?
YES - Fault is intermittent caused by poor contact in Sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Terminal and Connector Inspection" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "System Inspection" procedure.
SYSTEM INSPECTION
1. Check air clog.
1. Check Contamination, Gasket installation.
- Damage or installation of throttle body gasket.
- Check clog of air cleaner
- Clog or contamination of intake manifold or injectors caused by foreign materials
- Check vacuum hose connected to surge tank is normal.
2. Has a problem been found?
YES - Repair or replace as necessary and then, go to "Verification of Vehicle Repair"procedure.
NO - Go to "Check Fuel Pressure".
2. Check Fuel Pressure.
NOTE: Be cautious that fuel is explosive and empty fuel tank can still contain explosive gases. When working on fuel system, make sure to supply when the engine is not running. Release fuel system pressure before disconnecting any fuel line to reduce the chance of personal injury or fire damage to vehicle components.
1. Start the engine and disconnected the fuel pump relay.
2. Wait until fuel in fuel line is exhausted and the engine stalls.
3. Turn the ignition switch OFF position.
4. Install the special service tool for measuring the fuel pressure between the delivery pipe and the fuel feed hose.
5. Connect the fuel pump relay.
6. With fuel pressure applied, check that there is no fuel leakage from the fuel pressure gauge of connection part.
7. Start the engine and measure the fuel pressure at idle.
Specifications : 374 - 384 kPa (3.82 - 3.92 kg/sq.cm, 54.3 - 55.8 psi)
8. Stop the engine and check for a change in the fuel pressure gauge reading.
Specifications : After engine stops, the gauge reading should hold for about 5 minutes.
9. Is the measured fuel pressure within specification?
YES - Go to "Component Inspection" procedure.
NO - Repair or replace according to the table.
COMPONENT INSPECTION
1. Check PCV
1. IG "OFF".
2. Remove PCV valve and then, check that plunger in the PCV is moving.
3. Is the PCV normal?
YES - Go to "Check PCSV".
NO - Substitute with a known-good PCV and check for proper operation. If the problem is corrected.replace PCV and then go to "Verification of Vehicle Repair" procedure.
2. Check PCSV
1. IG "OFF".
2. Remove PCSV and Vacuum Hose
3. Check that PCSV is just one way solenoid valve
4. Is the PCSV normal?
YES - Go to "Check injector".
NO - Substitute with a known-good PCSV and check for proper operation. If the problem is corrected, replace PCSV and then go to "Verification of Vehicle Repair" procedure.
3. Check injector
1. IG "OFF"
2. Remove injector.
3. Check that injector hole is clogged by foreign materials.
4. Measure resistance between terminal 1 an 2 of injector connector. (Component Side)
SPECIFICATION:
Temp. Resistance
20 degrees C (68 degrees F) 11.4 - 12.6 Ohms
5. Is the measured resistance within specification?
YES - Go to "Check component related to fuel trim".
NO - Substitute with a known-good injector and check for proper operation. If the problem is corrected, replace injector and then go to "Verification of Vehicle Repair" procedure.
4. Check component related to fuel trim
1. Check component related to fuel trim such as HO2S, MAFS, MAPS, TPS, ECTS, PCSV and Injectors).
2. Are those component related to fuel trim O.K?
YES - Substitute with a known-good PCM and check for proper operation. If the problem is corrected, replace PCM and then go to "Verification of Vehicle Repair" procedure.
NOTE: There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM.
NO - Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code (DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness test have been verified as "Complete".
5. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.