MAF Sensor Question

[gadgety]

Hello,

I have a 1999 2WD Ranger 3.0L FF that is running rough. An OBD scan showed a DTC of P0102 (MAF or VAF A Ckt Low Input). A snapshot of the realtime data seemed to confirm a bad MAF sensor (the MAF flow would not vary from 0.05):

MIL STATUS ON
ABSLT TPS % 16.0
ENG SPEED RPM 1061
CALC LOAD % 39.6
MAF FLOW GR/SE 0.05
 COOLANT F 64
 IAT F 51
IGN ADVANCE DE 16.5
ST FTRM1 % -23.1
LT FTRM1 % 0.0
ST FTRM2 % -23.1
LT FTRM2 % 0.0
VEH SPEED MPH 0
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.870
ST FTRM11 % -23.1
O2S12 V 0.000
O2S21 V 0.800
ST FTRM21 % -23.1
OBD2 STAT CA

I changed out the sensor, cleared the DTC, but the engine still won't idle smoothly. A snapshot of the realtime data with the new MAF follows:

MIL STATUS OFF
ABSLT TPS % 16.8
ENG SPEED RPM 1065
CALC LOAD % 39.2
MAF FLOW GR/SE 10.72
 COOLANT F 118
 IAT F 60
IGN ADVANCE DE 30.5
ST FTRM1 % -23.1
LT FTRM1 % -2.2
ST FTRM2 % -23.1
LT FTRM2 % -2.2
VEH SPEED MPH 0
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.945
ST FTRM11 % -23.1
O2S12 V 0.875
O2S21 V 0.925
ST FTRM21 % -23.1
OBD2 STAT CA

Some questions:
1) Does anyone know what the MAF flow nominal value for this engine should be, at say 1000 RPM? (I'm not sure if the new sensor is good - it looks rebuilt)

2) Does the ECU need to recalibrate itself to the new sensor? Do I disconnect the battery (for how long)? and/or drive it for a few miles?

Any help is appreciated.

-TIA

 

[McCormack]

How much have you driven the vehicle after you swapped MAF's? You need to put some miles on in order to give the computer a chance to reset itself, and then hopefully your rough idle will clear up.

 

[gadgety]

Thanks to everyone who provided input on my question.

I just wanted to give you an update. I purchased a second refurb'ed MAF from RockAuto, and this time it was a Motorcraft part (the first one was a Standard part). Although the MC MAF looked really used/old, it did the job and the engine seems back to normal. I drove it around the area for 15 minutes, varying rpm and gears, going up hills, etc. and the engine response and idle are smooth again. No DTCs either. Hopefully it will stay that way.

I will attach a couple snapshots of the Motorcraft vs Standard MAF flow rates at about 2000 RPM. As you can see the Standard was way off. I read somewhere that someone else had a similar issue with non-OEM MAFs, but I figured his experience was a fluke. Live and learn.

Motorcraft MAF:
MIL STATUS OFF
ABSLT TPS % 20.7
ENG SPEED RPM 2085
CALC LOAD % 33.3
MAF FLOW GR/SE 10.50
 COOLANT F 190
 IAT F 109
IGN ADVANCE DE 20.5
ST FTRM1 % 2.3
LT FTRM1 % 0.0
ST FTRM2 % 4.6
LT FTRM2 % 0.0
VEH SPEED MPH 0
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.810
ST FTRM11 % 0.0
O2S12 V 0.720
O2S21 V 0.775
ST FTRM21 % 2.3
OBD2 STAT CA

Standard MAF:
MIL STATUS OFF
ABSLT TPS % 20.7
ENG SPEED RPM 2036
CALC LOAD % 34.1
MAF FLOW GR/SE 19.85
 COOLANT F 127
 IAT F 60
IGN ADVANCE DE 36.5
ST FTRM1 % -23.1
LT FTRM1 % -6.3
ST FTRM2 % -23.1
LT FTRM2 % -2.2
VEH SPEED MPH 0
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
O2S11 V 0.930
ST FTRM11 % -23.1
O2S12 V 0.900
O2S21 V 0.935
ST FTRM21 % -23.1
OBD2 STAT CA

 

[McCormack]

Thanks for giving us an update, and it's good to hear that you got things straightened away.