map sensor

[MUDWHISTLE]

Has anyone ever checked the signal voltage from the map sensor to the pcm? if so what is the range? I checked mine and at 0 psi to 25psi my signal voltage stays right at 2.35 volts I'm thinking that I have a problem and need some input. thanks in advance, Lee

 

[Patrick Feeley]

The signal produced is actually a variable frequency signal vice a varying voltage. I can probably locate the frequency versus pressure specs if you want them. Cheers!

Added in edit:

CONNECTOR VOLTAGE CHECKS
(CHECK WITH SENSOR CONNECTOR DISCONNECTED AND IGNITION KEY ON)

Test Points Spec. Comments

A (GR/R) to Grd 0-.25 volts If greater than .25 volts signal wire is shorted to VREF or battery.

B (BR/W) to Grd 5 volts +/- .5 VREF signal, should be 5 volts +/- 0.5.

C (LG/BK) to Grd 5 volts +/- .5 Signal line is pulled up to 5 volts +/- 0.5 volts when disconnected from sensor.

 

[95_stroker]

Hmmmmm.................

MAP Manifold Absolute Pressure Sensor
Strategy and feedback input. The PCM monitors manifold pressure to control fuel delivery in order to minimize smoke. It also optimizes injection timing for detected boost. It also monitors boost to limit fuel delivery to control maximum turbo boost. Frequency output: 111Hz = 14.7 psi, 130Hz = 20 psi, 167Hz = 30 psi.

 

[MUDWHISTLE]

So the map can control timing too then, correct? rich and I were chatting about the studdering/blubbering problem i have had for the last 60,000 miles and he thought maybe the map could be the cause but i don't really want to just buy a map and throw it on there and not have it fix it. any one have a link on strategy of the map? also with zero boost i would think that the signal should be lower then 2.35 volts and it shout rise as the boost comes up, right?

 

[Patrick Feeley]

Check my edit (which was posted while/after you guys were posting). Cheers!

 

[94f450sd]

mud,if you want i will overnight my MAP sensor to you to try.if it works go buy a MAP and send mine back overnite.

 

[MUDWHISTLE]

Thanks man I will try that and see what I come up with.

 

[MUDWHISTLE]

HMMMM I just measured the voltage and found that the

Green and red had 5 volts when unplugged and the key on.

brown/white has 5 with the key on

The grey/red has nothing other then around 17.0 milivolts. also it is light grey with red.

Thanks rich i might have you do that is your map grey or the black one? mine is grey IIRC that is the correct one.

 

[94f450sd]

mine is black i believe.i think the black one is the correct sensor but unsure,but still my truck runs perfect when it runs

 

[94f450sd]

the gray map is the right one.mud,check PMs in a minute