ml 3.2d map low volt/press p0107 errors

[koshari]

houstin we have a problem,

ml 3.2D started throwing cel errors/limp mode due to low manifold voltage / pressure code p0107.

put the scanner on it looked like this,



measuring on middle pin to ground



according to the manual

Judgment Criterion

The manifold absolute pressure sensor output voltage should is lower than 0.28 V for 0.5 seconds.

where as from what i can see it appears to be going well below that .28v for a good while longer than .5 secs on shutdown.

it did throw a code tonight while driving along however,

might have to take the map sensor into work and put on a 5v power supply and use a manometer to compare with known pressures but other than atmospheric pressure that looks correct at 100Kpa (1 AT ) i dont know if the other pressures are correct/expected.

can go a week without a cel then i get a few, seems to happen on hotter days but that could be a coincidence.

engine is stock standard with no egr blanking plate,

anyone have any data to compare to?

cheers.

[hvac guy]

It might be full of carbon in there.

But there has been a few failures on the map
Did U take the reading on the harness gnd or the battery gnd

U could have a earthing issue. or you're swirl valves are sticking or your egr valve sticking.

Causing low manafold pressure

[hvac guy]

Having a close look at the readings the engine is below 0 kpa. Sound like blockage in manafold is carbon build up. How many km on clock

[koshari]

there is no carbon blockages, inlet manifold is relatively clean as EGR valve was replaced by stealer about 6k ago, rubber hose and sensor are clean as a whistle.

done 176k

Did U take the reading on the harness gnd or the battery gnd

voltage reading taken from negative battery post and signal pin on map sensor

[dismatpe]

The elec diagram looks like the sensor is a strain gauge type (wheystone bridge). I'd be checking the 5v to the sensor is not dipping at the same time. If it is a strain guage then the output will most probably be a voltage output and thus low voltage could be open circuit or high resistance where it shouldn't be. Probably a dry/dirty contact in the circuit. Next step is swap sensor with a known working one to eliminate sensor. Have fun!

[koshari]

5 volt supply to sensor rail is solid as a rock,

ordered a new map sensor $220 from the local stealer's, (ouch)

sensing (middle pin) still dipping to .2 of a volt on engine shutdown for at least a full second

none in stock said they had another one on order!


edit: seems the voltage is dropping intermittently to around .18-.2volts regardless of the pressure then will read good for a bit, beginning to look pretty conclusive that its the sensor.

looks like the dip on shutdown isn't a problem/appears normal as i suspect the ECM stops monitoring the map pressure at that point.

[Tony]

MAP sensor should dip at shut down as the TB closes then returns to open at rest.

[koshari]

finally picked up replacement map sensor and replaced it yesterday,

edit: a week and no cels or limpys,