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Some boost fooler threads talk about a boost sensor. I'm familiar with the MAP sensor and there's possibly a separate barometric pressure sensor. Is there a separate boost sensor or is this a function of the MAP sensor?

Thanks,
Sixto
97 C2500 'burb 167K miles
 

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She Don't Smoke!
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The MAP sensor on our trucks are the only thing that reads boost.

Some trucks to have a "baro sensor" but that is part of the EGR system had has nothing to do with boost :).
 

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Where is the MAP sensor? I know of the IAT sensor, but I haven't run across the MAP. Obviously the ECU could extract approx pressure value from the temp with a stock setup, but I keep hearing about this MAP sensor.
 

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The MAP (manifold absolute pressure) sensor is on the intake hat.

The barometric pressure sensor (essentially another GM MAP sensor - may be different calibration/range) is typically on the firewall, with nothing connected to its sampling port.

The baro sensor relates to boost control by giving the PCM the ambient air pressure where the truck is operating (at sea level, at 8000 ft' etc.). So within the capability limits of a given turbo, the PCM/solenoid boost control tries to compensate for air density changes & provide the correct/intended mass airflow for a given fueling rate - regardless of altitude/varying air density.
 

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Heres a pic I made that may help...



And yes... my baro sensor in the picture is doing nothing... lol. I'm just been to lazy to take it off.
 

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Believe on F engines ( do not have a Baro sensor on the firewall ) the map(boost) sensor tells the ecm the barometric pressure at start up . but subsequent changes in barometric pressure (due to altitude & weather etc) are not taken into account. Could well be wrong.
Dont believe the 2 sensors are interchangable & parts people can get them mixed up due to teminology applied.
 

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Believe on F engines ( do not have a Baro sensor on the firewall ) the map(boost) sensor tells the ecm the barometric pressure at start up . but subsequent changes in barometric pressure (due to altitude & weather etc) are not taken into account. Could well be wrong.
Dont believe the 2 sensors are interchangable & parts people can get them mixed up due to teminology applied.
My '95 is an OEM F, and its got the baro sensor. But can't say I've really looked at other F engined trucks close enough to note it being there.

These GM sensors in that configuration have been used fairly widely in a lot of applications. The 2 bar & 3 bar GM MAP sensors are common, but I don't know with certainty if there are other calibrations.
 

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I don't believe F engines had the baro sensors either. My truck is actually an S engine but I have an F intake on it lol.

Vac system/solenoids all gone, I just have to remove my baro sensor :).
 

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On my 97 F engine there is only the boost sensor on the intake. Do remember Turbine Doc talking of F engines with the baro sesor as you mention.
 

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Sorry, was reponding to Smihvilles post . Am horribly slow.
 

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Again, I can only speak for my '95 F, but it's got one & I'm pretty confident it came that way:)

While it's a terrible quality pic, you can see the sensor in this pic of what the engine looked like when I bought the truck, stone-stock @ 157k miles.

Seems rather unlikely the old farmer that owned it added the sensor.

Sounds like the OBDII PCM went to a different strategy. I haven't looked at their function closely, but the later PCM has notably different capabilities.
 

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Again, I can only speak for my '95 F, but it's got one & I'm pretty confident it came that way:)

While it's a terrible quality pic, you can see the sensor in this pic of what the engine looked like when I bought the truck, stone-stock @ 157k miles.

Seems rather unlikely the old farmer that owned it added the sensor.

Sounds like the OBDII PCM went to a different strategy. I haven't looked at their function closely, but the later PCM has notably different capabilities.
You're right, my 98 F doesn't have the baro sensor.

I was under the impression that the barometric sensor was part of the boost system, so it could cross check boost, if the MAP gives a value that is out of wack compaired with the baro sensor, the engine opens the WG.

Example being, if you have a boost fooler on the MAP sensor, but not the baro, and you start fooling with the boost levels by making the computer see lower then actual readings, the baro gives out it's reading, and the computer is left goin "WTF?" So you'd actually have to fool both the MAP and baro to actually get more boost on a stock tune.

I could be wrong though, the altitude comment made sense as well.
 

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Sort of an unrelated question about the MAP sensor, while driving today my Service Engine Soon light came on.

So, I stopped on the way home at AutoZone and had them check for codes. The code they found related the MAP sensor and vacuum. It sounded pretty generic.

Should I get a second opinion? Could the MAP sensor be defective?

Thanks in advance!
Geoff
 

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my 94 has both sensors.if you mess with one for the boost fooler you need to do the same to the other one or you get codes 78 wastegate fault.I've got an F engine with 5068 injection pump and old z industries performance chip
 

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my '97 has the MAP on the firewall and the turbo boost pressure on the manifold... i learned that when i went to put on a new MAP and it was the wrong connector, but the right one for the firewall...
 

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DeadVeg what you have on the firewall is the Baro sensor, not a MAP sensor. You are correct, the plugs are different. When i went to replace my original MAP sensor they gave me a sensor with the wrong plug configuration. They had to order the correct one. Guess they gave me the baro sensor?

my OBD II 96 has the map and baro sensor all in one. I don't have a sensor on the firewall. the 94 CCLB "F" engine truck in my yard has a sensor on the intake and on the firewall like yours does. Must be an OBD I thing to have both sensors.
 

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every where i look the part number comes up map sensor (ac delco 213-1545 and gm# 12569240). i saw that standard motor products makes a turbo pressure sensor that will fit...pretty confusing...rock auto doesn't even list a barometer sensor... so is the turbo pressure sensor the equivalent of the map???
 

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every where i look the part number comes up map sensor (ac delco 213-1545 and gm# 12569240). i saw that standard motor products makes a turbo pressure sensor that will fit...pretty confusing...rock auto doesn't even list a barometer sensor... so is the turbo pressure sensor the equivalent of the map???
I guess so. :confused: Now you've got me confused. I"ll have to waste company time tomorrow and look up both parts and check the numbers. :p:
 

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rockauto has the delphi ps10082 listed as the turbo pressure sensor and amazon has it as the baro sensor, but amazon has a pic of the ps10082 and that's the one that fits...i'm guessing that's the right part. ;)
 
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