Barometric (Altitude) Sensor Location?

[Big MAK]

Anyone know which sensor is specific to barometric 'altitude' readings? I see that it's a parameter the ECM tracks specifically (a seperate reading from the MAPS).



Anyone know which one it is and where it's at? I suspect my '03 sensor is bad.

 

[Little Bill]

I believe the ECM reads the MAP sensor output at key-on, so it's not a dynamic measurement. This was true on my '01.

 

[nickleinonen]

the one on the intake air piping by the intake air filter. . it is the combo baro/iat sensor. . p0105 to p0109 codes for faulty baro sensor. .

 

[Big MAK]

hmm. No codes thrown but behaves like it's bad.

 

[nickleinonen]

i had one fail. . it kicked up a p0107 code. . the engine had a very nasty stumble at ~1900rpm then very heavy defueling after that. . if you drove it nicely it didn't stumble. when you were on the throttle hard and hit that 1900, it felt like the engine lost all boost instantly. .



what sympton is your truck having??

 

[Little Bill]

The doodad on the plumbing by the airfilter is a mass air flow sensor. Faults for that are P0100-0104.



P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction

P0106 Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem

P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input

P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input

P0109 Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent

 

[Big MAK]

Ordered one and putting it in tonight. I'm not building power after apporx 2400 -- it acts like it's on the rev limiter at 2350/2400. It'll build RPM all the way up to 3200 but no power since fueling gain stopped at 2350/2400.



I was told a flat line power curve in that range would typically be

1) torque management engaging

2) elevation sensor getting an incorrect signal -- they mentioned this is sometimes the case when a comp vendor thinks it's not an important signal to forward. I'm pretty sure my comps forward the signal so I think the sensor may be sending bad info but not enough to trip a code.

 

[nickleinonen]

The doodad on the plumbing by the airfilter is a mass air flow sensor. Faults for that are P0100-0104.

it is not a mass air flow sensor. it is a combined barometric pressure and intake air temp sensor.

SENSOR-TEMPERATURE/PRESSURE-INTAKE

DESCRIPTION

The combination, dual function Inlet Air Temperature/Pressure Sensor (4) is located on the air cleaner (filter) cover.

OPERATION

The Inlet Air Temperature/Pressure Sensor is a combination dual-function sensor. The sensor element extends into the intake air stream at the top of the air filter housing. Ambient air temperature as well as barometric pressure is monitored by this sensor. The Engine Control Module (ECM) monitors signals from this sensor.

 

[Little Bill]

My bad !



Lousy place for barometric pressure reading. The only time it will be correct is key on, engine off. Otherwise it will see lower than atmospheric depending upon filter condition, humidity and boost level. So I'll agree it reads absolute pressure on the intake side of the turbo but it cannot accurately and continuously measure barometric pressure.



It'd be very suitable to replace the mechanical filter minder !

 

[Big MAK]

Since this isn't a MAF would it actually read more accurately when not in it's mounting location? I. e. should I just zip tie it to the side of the engine compartment? It seems to me that'd be a more accurate reading. Maybe drill a hole in the fender where it feeds the airbox and get true intake air temp and barometric pressure without having it in a tube after the filter.



Mine is presently mounted in the AFE tube. The mounting position is such that the sensor is blocked quite a bit imo.

 

[nickleinonen]

it would read more accurate outside the piping, but then the ecm could not componsate fueling for an extremely plugged filter. i had mine like that for a long time when i switched to a bhaf. the only reason i stuck it in the piping was when i went in for warrenty work, and didn't want them asking any questions about it. made no difference in how the engine felt driving with it in the pipe or out of the pipe. i'd move it back out, but now i have a ~1/2" hole in the rubber elbow, so i'll leave it in place.



if you had the tooling to make a little scoop [venturi] for it, you could trick it to make the ecm think you are below sea level under boost, allowing more fueling. the flow of air across the venture would cause a higher pressure area while you are under heavy load [lots of air flow]. . but that is a lot of work for not much gain [or even setting a code if your venturi is too efficent and overpressurizes the sensor]

 

[bellsclan]

Is that the one that tells the relays to open in real cold weather, to heat the grid heaters?



Thanks, In alaska and having hard starting, grids work and relays r ok also



HOTRODDING IN ALSAKA