Check engine light

SWEDENDUDE

MEMBER
PONTIAC

I have a 2002 Trans Am WS6 automatic. I just replaced the mass flow sensor and put a k&N airfilter on it but thought after that, that the car felt a little weaker but still strong from idle, and at about 60 mph if I floored it, it missed like it hesitated and then came pretty strong, and aftera bout 150 miles the check engine light came on, and I have the code checked and here is what it said, code number PO171.
Definition: fuel trim bank one condition
Explenation: The powertrain control module uses the oxygensensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.
Probable causes: 1 If bank one and two codes set together suspect fuel pressure or mass air flow sensor.
2. Oxygen sensor defective
3. Ignition missfire-repair
4. Fuel injector problem
trouble shooting: the pcm has determined that during testing, the fuel system for bank 1 was to lean. (Bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinders on the opposite bank)
I had a new mass air flow sensor from granatelli that are supposed to flow more air and give more power but instead I got less power. But I have just put the stock mass air flow sensor back but the service engine light is still on. What do u think is the problem is it the mass airflow sensor that messed it up or oxygensensor or something else?

1 Reply

TOBYU

MEMBER
89 POSTS

WS-6 Great cars!
It would be hard to damage an O2 sensor in a short period of time. So

The P0171 is a common code with K&Ns. The oil on the filter coats the MAF sensor wires and pops the code.

On yours and all OBDII cars, the check engine light will stay on for a long time. Days. Unless you reset it with a scantool.

A misfire would be shown as a ingition misfire code.

Fuel injectors rarely go out on those.

I would clean out the plenum and throttle body throat good and clean off the MAF. The stock will have screens. It is common practice to remove at least one of them.I belive most performance sites recommend leaving one of them in. Try one of the F-body performance places. The aftermarket one you have might be easier to get to the resistors inside to spray off with brake cleaner.