Isuzu 2000 Trooper Workshop Manual page 1097

6E–228
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0171 – Fuel Trim System Lean Bank 1 (Cont'd)
Step
11 Check the fuel for excessive water, alcohol, or other
contaminants (see Diagnosis in Engine Fuel for the
procedure) and correct the contaminated fuel condition
if present (see Engine Fuel ).
Was the fuel contaminated?
12 1. Visually and physically inspect the PCM injector
grounds, power grounds and sensor grounds to
ensure that they are clean, tight, and in their proper
locations.
2. If a faulty ground condition is present, correct it as
necessary.
Did your inspection reveal a condition requiring repair?
13 1. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in "closed loop" while
monitoring the "BANK 1 S.T. FUEL TRIM" displayed
on the Tech 2.
Does "BANK 1 S.T. FUEL TRIM" value decrease to
near the specified value?
14 Perform the procedure in the "Fuel System Pressure
Test" and repair fuel system problem if necessary.
Did Fuel System Pressure Test isolate a condition
requiring repair?
15 1. Visually and physically inspect the intake manifold,
injector O-rings, EGR adapter, EGR valve and the
EGR feed pipes for vacuum leaks.
2. Repair any problem that is found.
Did your inspection reveal a problem?
16 Visually and physically inspect the Bank 1 exhaust
manifold for leaks and loose or missing hardware and
correct any problem found.
Did your inspection reveal a problem?
17 Perform the "Injector Balance Test," and correct any
problem found (refer to Fuel Metering System ).
Did Injector Balance Test isolate a problem?
18 1. Visually and physically inspect the Bank 1 HO2S 1
to ensure that it is installed securely and that the
Bank 1 HO2S 1 pigtail and wiring harness are not
contacting the exhaust or otherwise damaged.
2. If a problem is found, correct it as necessary.
Did your inspection reveal a problem?
19 Replace the MAF sensor.
Is the action complete?
Action Value(s) Yes
— Verify repair
— Verify repair
Go to Step 19
0%
— Verify repair
— Verify repair
— Verify repair
— Verify repair
— Verify repair
— Verify repair
No
Go to Step 12
Go to Step 13
Go to Step 14
Go to Step 15
Go to Step 16
Go to Step 17
Go to Step 18
Refer to
Diagnostic
Aids
—