I have a 2004 mazda6 v6 3.0 and it is throwing codes for o2 sensors. No cat but there is a code for heated o2 sensor. Not to Familiar with Mazda’s but when accelerating hard below 3000 rpm it seems to misfire or skip. Only when accelerating hard though. If just barley pressing the pedal and slowly creeping through low rpms it runs fine. Anything above 3000 rpm it accelerates great. Any ideas?
Spark plugs replaced recently?
Yes just replaced all spark plugs and a bad pcv valve. The pcv valve was causing timing to be over retarded. Only problem now is the acceleration under 3000 rpm
Did you use the exact same plugs as specified by Mazda?
(They probably specify an NGK or Denso plug)
When people attempt to substitute cheaper “equivalent” plugs from other manufacturers, it is not unusual to encounter drivability problems.
It had NGK plugs before I changed them and they were doing the same. Replaced with ac delco. They are a good brand don’t think spark is the problem here tho right? Considering a over 3000 rpm it pulls just fine and idles fine?
Forgot to mention it does not have this problem until the engine is warm. Before the engine gets to operating temp there is no skip below 3000 rpm
Even if those Delco plugs are not the proximate source of the current problem, I would suggest replacing them with the specified plugs. Many engines–particularly Japanese engines, in my experience–do not run well with any plugs other than the ones specified by the mfr.
In any event, I think that you need to check the wiring for the O2 sensors, and–possibly–to change them. Bad O2 sensors can lead to drivability problems.
When an engine is cold it’s running in open loop mode. Once it’s warm it runs in closed loop using all the sensor inputs. When you get a O2 heater failure, it’s usually the sensor. If it is failed the fuel and air mixture will be incorrect. This causes drive ability issues and can lead to catalytic converter failure. Get that fixed and I would go back to the OEM plugs. Also, check and make sure the coils/wire are fully seated on the spark plugs. They will make a clicking sound when the are on correctly.