MAP pressure readings
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
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From: Southwest Georgia
I don't what the max is that it will register, this would be good question for c00nhunter, TJ, or Cuda, someone who has all of the tech data and scanner info. I do know that it will receive boost in the 40 psi range but I don't know if it has maxed out the signal before that. I know on the 99+ trucks you have to have a boost bleed on the map line to keep it from defueling at high boost, I'm glad our trucks don't do this. I'll be watching this for the answer also.
Last edited by plowhand; Mar 20, 2009 at 03:05 PM. Reason: addition
Post Fiend
Joined: Apr 2004
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From: Silver Lake Dunes, MI
They usually won't register over 30 psi. Some lower not many higher. At about those pressures the MAP sensor gets confused and send a junk signal. Some trucks may not even like 25 PSI but most are ok even at 30 psi. My truck doesn't like 33 so I have a regulator to keep the MAP pressure at 28. Before the regulator I had some issues at high boost where the engine defueled due to the junk signal. Its not a function of the PCM. The pressures just go past the workable limit of the sensor.
Postmaster
Joined: Sep 2007
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From: Medford Oregon
They usually won't register over 30 psi. Some lower not many higher. At about those pressures the MAP sensor gets confused and send a junk signal. Some trucks may not even like 25 PSI but most are ok even at 30 psi. My truck doesn't like 33 so I have a regulator to keep the MAP pressure at 28. Before the regulator I had some issues at high boost where the engine defueled due to the junk signal. Its not a function of the PCM. The pressures just go past the workable limit of the sensor.
Can't remember where I got this so
wherever .. it does look about right.tj is correct as if you subtract baseline 14.7 PSI (sea level) then 30PSI is all this sensor can give input to PCM. After that who knows.
Fleet Owner
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From: AZ
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Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
The regulator I use is just a standard mini air pressure regulator you would use a on a small air tool or spray gun. Bought it at Lowe's and added barbed fittings to it to fit the MAP sensor hose. You may not need it as each truck is different. Mine truck would feel like a gasser hitting the rev limited at around 30-33 PSI. The regulator cured it. Most trucks don't need it though.
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