A code
P0171 may mean
that one or more of the following
has happened:
- The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use
of "oiled"
air filters may cause the MAF to become dirty if the filter is
over-oiled.
There is also an issue with some vehicles where the
MAF sensors leak the silicone
potting material used to protect the circuitry.
- There could be a vacuum leak downstream of the MAF
sensor
P0305 is cylinder 5 misfire (note if u get this code u have a misfire period. might not be able to tell by listening to or looking at engine but it there) ( if you hooked it up to a computer and monitor that cyl you would see the miss )
first thing i would do is test cylinder 5 fuel injector
to do this unplug cylinder 5 injector
then using a multimeter (if don't have one borrow one or buy a cheap one ) check the resistance of the injector should be around 12-15 ohms but very for different motors check one of the other injectors and if cylinder 5 reads close to other injectors it fine but if reads high or low replace it
second check for a vacuum leak
get some carburetor cleaner spray around intake gaskets vacuum lines etc. if idle changes u have vacuum leak there
thirdly clean the mass air flow sensor the make special spray for it which i highly recommend and should be under $5.00 the parts store u can use carburetor cleaner on it but not recommend because the carb cleaner can leave a residue on senor that will destroy it
if all above fails do a compression check on motor if cyl 5 reads lower than all others then there internal damage (bad rings, or burnt value )
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