HOW TO DIOGNOSE THE MAP SENSOR
To test the MAP sensor you will need a vachum pump, and a digital volt ohm meter capable of reading frequency. Hook the + lead of the meter on the center wire of the map sensor, and the - lead to the battery - post. Set the meter to read HZ, and turn key on (do not start engine), apply vachum and note the frequency readings. They must be within + or - 3 Hz.
MAP SIGNAL READINGS
| Vachum | Map Hz |
|---|
| 0 | 159 |
|---|
| 3 | 150 |
|---|
| 6 | 141 |
|---|
| 9 | 133 |
|---|
| 12 | 125 |
|---|
| 15 | 117 |
|---|
| 18 | 109 |
|---|
| 21 | 102 |
|---|
| 24 | 95 |
|---|
| 27 | 88 |
|---|
| 30 | 80 |
|---|
Now for those of you who have a digital dwell/tach meter, you are in luck. I just happen to have the little known MAP test procedure using the dwell/tach meter.You need to probe the MAP harness with the key on, and find the wire that has approximately 5 volts, then hook the dwell/tach leads to the othertwo leads. You set it to the 6 cylinder scale. Again, without starting the engine, turn key on, and apply vachum, and compare the RPM reading with the chart below, and this should let you know that the MAP is reading somewhat normally.
MAP RPM READINGS
| Vachum | RPM'S |
|---|
| 0 | 3134 |
|---|
| 5 | 2814 |
|---|
| 10 | 2538 |
|---|
| 15 | 2282 |
|---|
| 20 | 2016 |
|---|
I hope this helps in your quest for the finest running vehicle you can have. I will continue to expand and upgrade my pages to assist all of you home mechanics. Thanks for visiting my Fordman"s Page.
T L MILLER 11/17/1998