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

 

Ignition on, about 3v and at idle about 1v.

Let me know what you are getting and I might be able to advise.

 

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?

 

kPa values sound about right TBH.

 

Cheers Irvatron

Fingers crossed the CEL reset and clearing of the fault code will sort it.

 

Obviously give the map sensor a tap/thump and clean the contacts etc.

 

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?

 

It seems to be running fine now, will be keeping a eye on it over the next few days though.

 

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

 

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.