2004 Mazda 6 Engine hesitation

BBMAZDA

MEMBER
2004 MAZDA 6
6 CYL
FWD
AUTOMATIC
85,000 MILES

I am experiencing hesitation with my 2004 Mazda 6 V6 sportwagon EXACTLY like the person who posted their problem in 2008. I also was able to retrieve PO170 and PO 171 codes using an OBD reader from the local Autozone store. Supposedly, too lean on the left and right cylinder banks.
I have replaced the plugs, cleaned the MAF, and replaced the PCV valve and hose. The check engine light is out, but maybe because in will take a few miles to register new trouble code(s). Still hesitating the same or worse than before. I plan on changing the fuel filter (integral with the pump in the tank) or the coils next. At $65 each, I'd like to be certain before replacing them. Any advise or past history would be appreciated.
Here is the header for the posted problem in 2008.

Posted at Mon Dec 01, 2008 6:28 pm
By cozmotone, Have Donated
Give Feedback | Votes: 0

Engine Mechanical problem
2004 Mazda 6 6 cyl Automatic 48k miles

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

P0171/P0174

A lean fuel condition:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

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Sunday, January 10th, 2010 AT 11:38 PM

BBMAZDA

MEMBER
3 POSTS

Thanks for the feedback - I have replaced the PCV and hose and cleaned the MAF sensor. It seems like the problem is more apparent when the engine is under slight load. Especially at 40mph and on the verge of shifting from 4th to 5th gear. When I took the intake manifold of to access the rear plugs and pcv valve there was quite a bit of oil residue in the manifold and on the EGR tube. How can I check the EGR valve? Do you recommend dealer for the fuel injection cleaning or is there a good over-the -counter system?

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Monday, January 11th, 2010 AT 9:15 PM

RASMATAZ