P0171 Mazda - 3 2008 (Automatic)

Question

Help…
Was over oil change by 1,000 miles. Noticed lack of power on acceleration, and car stalled out in driveway - CEL went on. Went to Walmart (don't bash me here please - it was what my budget allowed) changed the oil (was low by a quart) and had them flush the engine with a detergent. CEL went off drove fine but a little sluggish for a few days. Did local driving and a little highway driving and CEL came back on. Went to O'Reillys had them run a CEL check and got a 0171. They suggested changing the spark. I swapped in a new spark CEL went off for a few more days. Still had questionable power on acceleration. Figured WM didn't flush engine good enough, went back to O'Reillys ran ceh check again, same code 0171 - threw a can of Seafoam in the tank and filled up. Few more days, driving fine (better acceleration). Today, CEL came back on again - went to O'Reillys again, check engine code - same came up 0171. They said to go onto highway and open it up to blow out the "clogs" and clean her out. I had to make a stop before going onto the highway and the engine wouldn't start in the parking lot - turned the key and it stalled. Finally got it started and went onto highway. I floored it and it went to 6,000 RPM barely got up to 60MPH - stayed in 5. Noticed this every time I floored it, barely any power, stayed in 4 or 5 when accelerating, felt a jump or surge at times. Drove for about 7 minutes on highway. Pulled off and turned around to head home. Stopped for an errand on way back and the engine had a hard time starting again.

Not sure what I should do… any help would be appreciated. Thanks.

Answer 1

P0171 Fuel trim lean

This code is a condition that has nothing to do with changing oil, or being low on oil. Changing the sparkplug was a good thing to do in this code case P0171 .What this mean is that there is more air than to fuel ratio.That is why it has a hard time starting.I would like to say this is a fuel problem but you achieved 60 MPH and at time you felt it surge? So this becomes more of a air induction problem, This engine uses a MAF (mass air flow) if that air duct from the air cleaner to the throttle is torn or not properly fitted  it will allow false air and the MAF will under report and cause a lean condition.This is most probable so you will need to check for this,