My 1997 pontiac grand am 2.4l
Dear JK: Had miss fire problem first, replacing the ignition
parts fixed problem. But, cat went bad. Replaced cat and front and rear
o2 sensors.Then gas cap for evap leak. Now have a p0420 code.Is it the
cat or rear o2 sensor? or something else? mass airflow or map sensor?
Thanks for your help,if you could respond soon it would really help
me. Because I think the shop that replaced the cat is trying to get out of
warranty. Thanks
JK:
Hello and welcome. Since you seem to be in a bind, i will help now. We were
all taking a break for a while, its been busy. P0420 is cut and dry 'cat.
converter Inefficient' 99% of the time it IS the converter. Have only had 1 bad
post cat. O2 sensor cause this in the last 10 years. If the post cat. o2 is bad,
it will set a code for 02 sensor, not usually catalytic Inefficient.
Dear JK: Had miss fire problem first, replacing the ignition
parts fixed problem. But, cat went bad. Replaced cat and front and rear
o2 sensors.Then gas cap for evap leak. Now have a p0420 code.Is it the
cat or rear o2 sensor? or something else? mass airflow or map sensor?
Thanks for your help,if you could respond soon it would really help
me. Because I think the shop that replaced the cat is trying to get out of
warranty. Thanks
JK:
Hello and welcome. Since you seem to be in a bind, i will help now. We were
all taking a break for a while, its been busy. P0420 is cut and dry 'cat.
converter Inefficient' 99% of the time it IS the converter. Have only had 1 bad
post cat. O2 sensor cause this in the last 10 years. If the post cat. o2 is bad,
it will set a code for 02 sensor, not usually catalytic Inefficient.
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Problem with my 2001/ Pontiac / Grand Am
2.4 L
GM Computer codes = no
Changed spark plugs
Work done to repair this problem = changed spark plugs
GM tech = JK
question = The car intermittently misses under normal driving conditions every once in a while.
Changing the spark plugs makes it go away but a day or so later it comes back.
JK:
If changing the plugs helps, i would look closely at the plugs that were removed. Make sure they all
seem the same color. If one is oil fouled, or looks a little greenish or orange (depending on which
coolant is in the system at this time) this would indicate an internal engine problem. If one is totally
black, this would indicate a rich fuel condition which may be caused by a faulty injector or is more
than one is black, then i would suspect a leaking fuel pressure regulator. MORE...
2.4 L
GM Computer codes = no
Changed spark plugs
Work done to repair this problem = changed spark plugs
GM tech = JK
question = The car intermittently misses under normal driving conditions every once in a while.
Changing the spark plugs makes it go away but a day or so later it comes back.
JK:
If changing the plugs helps, i would look closely at the plugs that were removed. Make sure they all
seem the same color. If one is oil fouled, or looks a little greenish or orange (depending on which
coolant is in the system at this time) this would indicate an internal engine problem. If one is totally
black, this would indicate a rich fuel condition which may be caused by a faulty injector or is more
than one is black, then i would suspect a leaking fuel pressure regulator. MORE...