Checks
| Action
|
DEFINITION: Momentary lack of response as the accelerator
is pushed down. Can occur at any vehicle speed. Usually more pronounced
when first trying to make the vehicle move, as from a stop sign. May
cause the engine to stall if severe enough.
|
Preliminary
|
| • | Search for service bulletins. |
|
Sensor/System
|
| • | Check the oxygen sensor (O2S 1). The O2S 1 should respond
quickly to different throttle positions. If not, check the O2S 1 for
silicon or other contaminants from fuel or the use of improper RTV
sealant. The sensors may have a white powdery coating. Silicon contamination
causes a high but false O2S 1 signal voltage (rich exhaust indication).
The PCM will reduce the amount of fuel delivered to the engine, causing
a severe driveability problem. |
| • | Check for proper operation of the MAP sensor. |
| • | Check for proper operation of the TP sensor. |
| • | Check for proper operation of the ECT sensor. |
|
Fuel System
|
| • | Check items which can cause an engine to run rich--the Long
Term FT is significantly in the negative range. Refer to Diagnostic Aids
for
DTC P0172
. |
| • | Check items that can cause an engine to run lean--Long Term
FT is significantly in the positive range. Refer to Diagnostic Aids for
DTC P0171
. |
| • | Check for proper operation of the evaporative emission (EVAP)
control system. |
|
Ignition System
|
| • | Check for proper ignition voltage output with the spark tester J 26792
or equivalent. |
| • | Check the spark plugs for the following conditions: |
| - | Wet or fuel fouled spark plugs |
| - | Cracks on the spark plugs |
| - | Improper spark plug gap |
| - | Burned electrodes or heavy deposits |
| • | Using the scan tool and monitoring the cylinder misfire screen
can aid in pinpointing a specific cylinder fault. |
| • | If the spark plugs are fuel or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
| • | Check the ignition control module (ICM) for proper ground connection. |
| • | Check the ignition coils for cracks or carbon tracking. |
| • | Check the spark plug wires for proper resistance and condition. |
|
Additional Checks
|
| • | Check for proper operation of the Automatic Transmission. |
| • | Check the generator output voltage. Repair the generator if the
output voltage is less than 11 volts or more than 16 volts. |
| • | If all procedures have been completed and no malfunctions have
been found, review and inspect the following items: |
| - | All electrical connections within the suspected circuit and/or
systems |
| - | If the short term fuel trim is attempting to lean an engine with
a rich condition--the negative fuel trim numbers are above 20--hesitation
on tip in throttle is usually the result. |
|
