MAF Diagnosis

[SniveTroll]

i came across where my MAF sensor was getting erratic readings. so erratic my maf would give my an ultra rich idle and cruise ratio of 12.9 .. i knew this is bullshit. it was tuned and ran perfectly. i havent done anything after the tune except upgrade my cold side piping to 3".\

*idle with maf connected: 12.x idle

*maf connected idle: 10.x

*maf disconnected: 13.6 idle

*o2s are new and switching as they should.

i used a FLUKE multimeter with alligator clip that i purchased from ebay. i also verified wiring through the 1996 mustang TSM. From my time in the military and doing electrical readings. this tool is invaluable.

on wires A B C D on the maf i notched each with a razor. i did so just enough to expose the wiring.

This Test is to verify the MAF doesnt work. During this test if you have an O.L or 0.00 means you do not have this procedure correct or your wiring is at fault.

1. wire A. (red wire)

note: with engine off and Key on.

a. turn multimeter to VOLTS DC MODE

b. connect POS multimeter probe to Wire A

c. connect NEG multimeter probe to NEG terminal on battery.

note: it should read 12v or 11.68... if voltage exists thats correct. if NOT try again

2. wire B. (black wire)

note: with engine off and Key on.

a. put multimeter in VOLTS DC MODE

b. connect NEG Black probe to wire B

C. Connect POS Red probe to + battery terminal

note: it should read 12v or 11.68... if voltage exists thats correct. if NOT the try again.

3. wire C. ( tan, Light brown/green or blue)

note: with engine off and Key on.

a. put multimeter in VOLTS DC MODE

b. connect NEG black probe to wire C

c. connect POS red probe to + battery terminal

note: you should have 12v or 11.68v DC. if voltage exists thats correct. if NOT the try again.

4. Wire D. (blue, Blue/red stripe)

note: with engine off and Key on.

a. Connect POS Red probe to Wire D

b. connect NEG black probe to NEG - terminal

c. Crank up the engine to idle. write down the value remember this is a 5v Return Signal. idle should be around 1 and some change.

d. manually rev engine release throttle body lever observe the meter. it should rise and engine settle smoothly. write down this after Revving value. if sensor is bad ,it will erraticly spike or skip numbers.this is a MAF resolution error. If the MAF Sensor is good, the Values should rise and fall smoothly and without gaps. it will also be about the same number originally wrote down.