Mag's OSE 12P Thread

[VL400]

Thats what i am trying to work out. Post a log from before you start the car, start it and then drive around under varying loads. Wanna see where the baro starts at, when it changes and why its going to such a low value.

[mag]

Here is a simple question from a simple mind, what sensor provides the baro info.

[Jayme]

the map sensor. on keyon while the engien is not runnning the manifold is at atmospheric pressure and that reading is saved as the baro. between a certain rpm and above a certain throttle position also should be atmo pressure and it saves that again periodically as you drive. what VL400 was gettin at is because you never went full throttle it shouldnt have reset the baro.

maybe your circuitry to recalibrate the funny map sensor hasnt fully initialised at keyon? this is why we need you to take a log that starts at keyon and keep it running while you start the engine, go for a drive and use soem full thorlttle. we need to see what the baro is under all those conditions and why it changes to 67

[mag]

Thanks Jayme, another piece of the puzzle. another question from the novice, if the MAP provides baro info at keyon & it is a 2 bar MAP, is the keyon MAP voltage scaled to compensate the the lower output of the 2 bar MAP. also should the adx file conversion equation for the baro value be changed for the same reasoning.

[Holden202]

the map sensor will be right no matter weather the key is on and the engine is off or on .... adx shouldn't need anything changed for the baro

[VL400]

another question from the novice, if the MAP provides baro info at keyon & it is a 2 bar MAP, is the keyon MAP voltage scaled to compensate the the lower output of the 2 bar MAP. also should the adx file conversion equation for the baro value be changed for the same reasoning.

Yes it uses the scaled value, which also means the baro definition in the adx does not have to be changed when using different MAP sensors.

[mag]

my apologies for wasting people's time looking for solutions to a problem of my own making.

after checking the output of my diy MAP at ignition on & engine running, the MAP output is not linear, as suggested as the problem by delcowizzid at one point. effectiely the MAP was providing a low output at high presseure, which was why the baro values were low, & a high reading at low pressure which was why the idle was poor but if engine loads were light the manifold pressure value would be correct.

there is no reason the sensor should not work & I have not given up on the idea but in the mean time I will use the GM factory 2 bar MAP when it arrives. at least I have learned a little more about how the declo/$12P system works from your kind assistance.

[VL400]

No probs at all mag, glad that its all been sorted in the end. Be sure to post your results on the GM 2 Bar sensor when it arrives too.

[mag]

As luck would have it the 2 bar sensor arrived today & I may also have found the cause of the diy sensor problem. will let you know they both end up.

[mag]

am running GM 2 bar MAP & all is well. mods to diy MAP almost complete, hopefully it will work too.

although my v6 bin is pretty basic, it runs well as a daily drive, I can post it if anyone is interested.