ewill thanks for the reply take a look at this could it be the MAF sensor?
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Numerous manufacturers have been
having troubles with their mass airflow (MAF)
sensors recently. The affected sensors are a
Bosch product used widely by foreign and domestic
manufacturers. The symptoms range
from hesitation to stalling to bucking on acceleration.
The malfunction indicator light (MIL)
is often illuminated. The diagnostic trouble
code (DTC) may or may not indicate a faulty
MAF sensor. On many vehicles DTCs P0171
or P0174 for system too lean may be set.
Sometimes an oxygen sensor DTC will be set
as well because the system is running so lean
that the sensor voltage consistently stays low.
Several manufacturers have technical service
bulletins published regarding this problem.
The suggested repair for the problem is to replace
the sensor.
The fault with the sensor appears to
be contamination of the sensor’s hot wire.
The sensor wire is heated to a particular temperature.
Air passing across the sensing wire
cools it. The sensor increases the current to
maintain a constant wire temperature. The
more airflow across the wire the greater thecurrent required to maintain the wire temperature.
This varying current is converted to a
variable frequency that the PCM uses to infer
intake airflow. When the wire becomes contaminated,
the airflow across it does not cool it
as it should. The current is not increased as
much and the PCM “sees” less airflow than is
actually occurring. This results in a lean air/
fuel mixture.
In order to diagnose the sensor, some
suggest cleaning the hot wire with Brake
Kleen or electric cleaner. Lint from low quality
air filters is a very common culprit. Excessive
oil on a K and N air filter will also contaminatethe hot wire and limit its sensitivity. Some
technicians are carefully pulling lint off of the
sensing wire with tweezers. After cleaning the
wire, drive the vehicle to see if the symptoms
have lessened. If so, the sensor is the faulty
component. Some technicians are cleaning the
sensors without replacing them though most
are following the manufacturers suggestion and replacing the sensors.
