Map Sensor Pressure Reading
#1
Registered User
Thread Starter
Map Sensor Pressure Reading
My friend has just popped over as his car has thrown a CEL and the fault code was P0108 - Manifold Absolute Pressure High so I am guessing it may be to do with his MAP sensor.
I have reset the CEL and cleared the code, then did a data log of what the pressure readings were and it all seemed pretty steady both with the data and the graph that was shown.
So, does anyone know what the readout should actually be? We did the MAP whack and now its just a matter of waiting to see whether they come back on otherwise.
Cheers,
Floppy
I have reset the CEL and cleared the code, then did a data log of what the pressure readings were and it all seemed pretty steady both with the data and the graph that was shown.
So, does anyone know what the readout should actually be? We did the MAP whack and now its just a matter of waiting to see whether they come back on otherwise.
Cheers,
Floppy
#3
Registered User
Thread Starter
I didn't check the voltage as the fault code reader didn't pick that up i dont think...
The intake manifold pressure was at approx 30kpa when I first connected it and it read a steady 25kpa during the drive we went for unless we booted it and then the min value was 12kpa and the max was about 102kpa.
I can check the voltage somehow with a volt meter I'm guessing?
The intake manifold pressure was at approx 30kpa when I first connected it and it read a steady 25kpa during the drive we went for unless we booted it and then the min value was 12kpa and the max was about 102kpa.
I can check the voltage somehow with a volt meter I'm guessing?
#7
Registered User
Thread Starter
Yeah we did that to try and persuade it to come back to life as soon as I saw what the fault code was
Wayne said that the battery was changed a couple of days ago, could that have affected it in some way and caused a temporary glitch?
Wayne said that the battery was changed a couple of days ago, could that have affected it in some way and caused a temporary glitch?
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#9
I would expect the MAP to be about 100 kpa at engine off.
This is close to 1BAR which is about atmospheric pressure(and MAP are showing an Absolute value).
So, 30kpa is very low engine off.
At idle and therefore drawing a vacuum I would expect a lower value though, maybe 30kpa and on the overrun, much lower again.
Poor vacuum pull at idle often is due to a high AFR, running very rich like 11:1 or worse
HTH
Steve
This is close to 1BAR which is about atmospheric pressure(and MAP are showing an Absolute value).
So, 30kpa is very low engine off.
At idle and therefore drawing a vacuum I would expect a lower value though, maybe 30kpa and on the overrun, much lower again.
Poor vacuum pull at idle often is due to a high AFR, running very rich like 11:1 or worse
HTH
Steve
#10
It depends what scenario, obviously it will depend on altitude but Steve rights. However with readers when I've logged mine, my VAFC2 would be the opposite of what a code reader would be.
But generally OTTOMH
Idle: ~30kpa
WOT: ~100Kpa
Crusing about 60-70kpa.
So from what you say...
Engine off ~100kpa, WOT~100kpa, engine on idling should be 30kpa
It should jump up very quickly after idling if you watch it.
But be aware other problem could cause errenous MAP sensor readings like vacuum leaks, ign timing, valve timing adjustments and low fuel pressure etc.
But generally OTTOMH
Idle: ~30kpa
WOT: ~100Kpa
Crusing about 60-70kpa.
So from what you say...
Engine off ~100kpa, WOT~100kpa, engine on idling should be 30kpa
It should jump up very quickly after idling if you watch it.
But be aware other problem could cause errenous MAP sensor readings like vacuum leaks, ign timing, valve timing adjustments and low fuel pressure etc.