Workshop Manual

6E–228
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0172 – Fuel Trim System Rich Bank 1 (Cont'd)
Step NoYesValue(s)Action
8 Inspect the MAF sensor inlet screen for damage or for
the presence of foreign objects which may partially
block air flow through the screen and correct any
problem found.
Did your inspection of the MAF sensor reveal a
condition requiring repair or replacement?
— Verify repair Go to Step 9
9 Start the engine and note the idle quality.
Is a low or unsteady idle being experienced?
— Go to Step 10 Go to Step 11
10 1. Ignition “OFF”.
2. Physically inspect the throttle body bore and throttle
plate for coking and foreign objects.
3. If a problem was found, repair as necessary.
Did your inspection reveal a condition requiring repair?
— Verify repair Go to Step 11
11 1. Disconnect the vacuum hose from the fuel pressure
regulator and inspect the hose for the presence of
fuel.
2. If fuel is present in the vacuum hose, replace the
fuel pressure regulator (refer to
Fuel Metering
System ).
Did the fuel pressure regulator require replacement?
— Verify repair Go to Step 12
12 Ignition “ON”, engine “OFF”, monitor the TP1 Angle
display on the Tech 2 while slowly depressing the
accelerator pedal.
Does the TP Angle display increase steadily and
evenly from minimum value at closed throttle to
maximum value at wide-open throttle?
Minimum 8%
Maximum
92%
Go to Step 13 Go to Step 21
13 1. Disconnect the MAF sensor electrical connector.
2. Operate the vehicle in “closed loop” while
monitoring the “BANK 1 L.T. FUEL TRIM” and
“BANK 1 S. T. FUEL TRIM” display on the Tech 2.
Did both values change to near the specified value?
0% Go to Step 22 Go to Step 14
14 1. Perform “Fuel System Pressure Test”.
2. If Fuel System Pressure Test isolates a problem,
repair as necessary (refer to
Engine Fuel or Fuel
Metering System ).
Did the Fuel System Pressure Test isolate a problem
requiring repair?
— Verify repair Go to Step 15
15 1. Ignition “ON”, engine “OFF”.
2. Connect a test light between the harness connector
terminals of canister purge solenoid.
Is the test light on?
— Go to Step 16 Go to Step 19
16 Check for short to ground in the wire (YEL/RED)
between the canister purge solenoid and PCM terminal
S-48.
Was there a short to ground?
— Go to Step 17 Go to Step 18
17 Repair the short to ground.
Is the action complete?
— Verify repair —