MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-592
STEP 6. Check the following items.
(1) Check the following items, and repair or replace the
defective items.
a. Check the injectors for fuel leakage.
b. Check the ignition coil, spark plugs, spark plug cables.
c. Check compression pressure.
d. Check the positive crank case ventilation system.
e. Check the evaporative emission control system.
f. Check the EGR system.
(2) Then check the malfunction symptom.
Q: Is the malfunction symptom is eliminated.
YES :
The check is completed.
NO :
Replace the catalytic converter. Then confirm that the
malfunction symptom is eliminated.
INSPECTION PROCEDURE 23: Transient, Mass Emission Tailpipe Test Failure.
.
COMMENT
•
The test is failed when the air/fuel ratio is not con-
trolled to the ideal air/fuel ratio. This occurs due
to the feedback control by heated oxygen sensor
signals, insufficient EGR flow rate, or deteriorated
catalyst.
NOTE: If the three-way catalyst temperature is low
when checking the exhaust gas, the three-way cata-
lyst cannot sufficiently clean the emissions. Warm up
the engine sufficiently before checking the exhaust,
and check immediately.
.
TROUBLESHOOTING HINTS (The most likely
causes for this case:)
•
Malfunction of air/fuel ratio control system.
•
Malfunction of the EGR system.
•
Deteriorated catalyst.
DIAGNOSIS
Required Special Tool:
•
MB991502: Scan Tool (MUT-II)
STEP 1. Check the exhaust gas with the engine at normal
operating temperature.
Q: After enough warm up, was the exhaust gas checked
enough?
YES :
Go to Step 2.
NO :
Check it again after enough warm up.
