Map sensor issue

[thethinkingman]

Hi all, my map sensor on my E48 setup doesnt seem to be right. Its a Marelli 216kpa, i tried the pressure offset value to get 100kpa with the engine not running but the reading stays at 172 no matter what. I believe the wiring to be correct and the sensor itself was working fine when i took it off a friends car. Can anyone shed some light? Thanks

[stevieturbo]

Unplug the sensor...does the reading change ?

Short 5v and signal wire, does the reading change ?

[adamw]

Note there are two different pinouts for the common Marelli map sensors so you probably have the wrong one.

[thethinkingman]

Stevieturbo - if i unplug it i get a reading of 100.

Adamw - i wasnt aware of that. I looked at a marelli tech page and wired it accordingly

[Rob Stevens]

In general engine settings there is a figure to be used on sensor failure, I suspect that this is set to 172?
In the real time info window if the MAP sensor is red the ecu thinks the sensor is failed, this is the same for all the sensor readings, likewise in 'engine diagnostics'

As suggested above first check the input is working ok by dabbing 5v onto the signal input, if that's ok then check the wiring to the sensor.

[Rob Stevens]

Ah so the default must be set to 100 in general engine settings then

[Rob Stevens]

So if you suck or blow the sensor does the reading change?

[thethinkingman]

Rob, yes i believe the default is 100 and in the real time window theres no indications of a failed sensor. Ive tried blowing/sucking on the map sensor line but still nothing.
I'm now wondering if it is indeed a wiring issue although i am fairly confident i got it right when i made the loom up. I take it if i dab 5v to signal and i get a reading then it must be a sensor issue

[stevieturbo]

Unplugging and 5v'ing the wires will at least prove wiring and ecu are working. ( and a slight assumption signal ground is ok )

After that you need to ensure wiring is correct for your sensor, and then that the sensor is also working.

[thethinkingman]

I will do some investigating later today and see whats what. Really hoping its not a wiring mistake as ive well and truly heat wrapped it all etc