Workshop Manual

6E–530
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom
Step Action Value(s) Yes No
1 DEFINITION:
Momentary lack of response as the accelerator is
pushed down. Can occur at any vehicle speed. Usually
most pronounced when first trying to make the vehicle
move, as from a stop sign. May cause the engine to stall
if severe enough.
Was the “On-Board Diagnostic (OBD) System Check”
performed?
— Go to Step 2
Go to OBD
System
Check
2 Was the “Electric Throttle Control (ETC) System
Check” performed?
— Go to Step 3
Go to ETC
System
Check
3 1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
— Verify repair Go to Step 4
4 Was a visual/physical check performed?
— Go to Step 5
Go to Visual/
Physical
Check
5 1. Check the fuel control heated oxygen sensors
(HO2S, B1S1 and B2S1). The fuel control heated
oxygen sensors (HO2S) should respond quickly to
different throttle positions. If they don’t, check them
for silicon or other contaminants from fuel or use of
improper RTV sealant. The sensors may have a
white powdery coating.
Silicon contamination causes a high but false
HO2S signal voltage (rich exhaust indication).
The PCM will then reduce the amount of fuel
delivered to the engine, causing a severe
driveability problem. For more information, refer
to Powertrain Control Module (PCM) and Sensors .
2. If a problem is found, repair as necessary.
Was a problem found?
— Verify repair Go to Step 6
6 1. Check the fuel pressure. Refer to Fuel System
Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
— Verify repair Go to Step 7
7 Observe the TP 1, 2 angle display on the Tech 2 while
slowly increasing accelerator pedal depression.
Does the TP angle display steadily increase from 8 ∼
10% at closed throttle to 90 ∼ 92% at WOT?
— Go to Step 8 Go to Step 9
8 Monitor the long term fuel trim on the Tech 2.
Is the long term fuel trim significantly in the negative
range (rich condition)?
— Go to Step 9 Go to Step 10
9 1. Check items that can cause the engine to run rich.
Refer to
Diagnostic Aids in DTC P0172 Diagnostic
Support
.
2. If a problem is found, repair as necessary.
Was a problem found?
— Verify repair Go to Step 11