Problem: The customer complained that the car had no power and poor acceleration primarily in the mornings when it was cold.
Details: The technician verified the low power, poor throttle response and slow acceleration during cold engine operation conditions.
No DTCs were set – when the engine reached normal operating temperature, it ran normally.
The catalytic converter had already been replaced and the muffler and resonator were original.
The technician pulled the front O2 Sensor to install an exhaust back pressure gauge. Test results were good – 2.8 psi at 2000 RPM.
Long Term Fuel Trim while cruising and during heavy acceleration was staying at +16%.
Confirmed Repair: On recommendation of the Tech-Assist consultant, the technician disconnected the Mass Air Flow (MAF) and the Long Term Fuel Trim slowly dropped to zero. He replaced the MAF sensor and the engine ran normally.