I'm posting from UK, I have a 94 Maxima with 118k miles which has an erratic fault. Apart from this the car is in good order.
The symptoms are good performance from cold but misfires and poor response to the throttle as it warms up. Suggesting good open loop running and a fault as it goes into closed loop.
The exhaust gets very hot and it has just scraped through our annual test with a high lambda reading, suggesting un burnt fuel is carrying over and being burnt in the exhaust.
The problem is getting worse and yesterday it went into "limp home" mode again, with revs limited to 2000.
I've checked the flash code and got a code 12, mass flow meter or circuit fault.
On clearing the code and starting from cold this morning there is no problem and the fault codes are clear.
The mass flow meter has 4 wires, white+black, black, black then white. The two black wires show about 4 Ohms resistance to earth and when the ignition is on the white+black terminal carries battery voltage.
Ignition on and engine off the signal (WHITE) gives .3V between it and ground, at idle 1.5V and with the torque converter stalled at 2500rpm and full throttle 2.8V. So on the surface it appears to be working.
Anyone with any ideas what next to look for?
AJH