LB7: MAP/Boost pressure

[rupertalf]

So here's some back story, I went to install a batmowheel into my stock turbo. Basically the turbo bearings and everything were shot and the compressor and turbine wheels were hitting the housing. Lucky me I got to get a new turbo. So now days later the new turbo is in and everything is put together. But during the install the MAP sensor was cracked. So I got a new one to prevent any future problem. Go to start the motor and waiting for the light to go out, I see the boost was reading a constant 38 PSI without the engine running. So I start the motor hoping the computer would adjust or whatever. Nope, stayed at 38 PSI plus or minus .2 psi and the check engine light came on. So I checked voltage at the sensor, checked continuity from the ECM pins to the MAP sensor and everything was checking good. So I figured it had to be a bad from stock MAP sensor. Went to the dealership and got the OEM MAP sensor. Nope, still a problem. So brought it to a shop to see if the could figure it out. Got it back from them and it is now reading 2.8 PSI to 3.1 PSI constantly engine on or off, but the check engine light is out...so that's a plus.

I do have the Banks Six Gun in there but I've checked the wiring and sensor reading with it installed and disconnected, and it's the same.

So has anyone ran into this issue ever before. I tried searching everywhere and have seen nothing about this. All I can think left is the ECM may need to be flashed.

 

[C.bowles2]

Take the banks totally out of the equation then check. Your map/boost sensor should read barometric pressure koeo i believe. So it should match your baro pid also




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[rupertalf]

Sorry was busy all weekend. I will do that and post what it reads when I get a chance to. Working night shift makes it difficult to accomplish much during the week unfortunately.

 

[THEFERMANATOR]

Are you getting a MAP or boost pressure sensor? They look the same, but are different. Theres the MAP sensor over on the drivers side of the engine down under the engine bale connectors that reads atmospheric pressure to tell the ECM what altitude you're at. For an 02 there is the boost pressure sensor I believe that hooks up to the intake on the passenger side in the aluminum intake portion coming off of the intercooler pipe. If you put the wrong sensor in, it will max out the reading, or read way off. Aliminate the BANKS to make sure that isn't your issue, but also make sure you are telling them the correct part that you need as the MAP and boost pressure sensor are different parts, but both are used on your truck.

 

[rupertalf]

The Baro sensor is still stock and I got the proper boost sensor (MAP sensor) from the dealer themselves $$. And when I took it to the shop (prior to me even going to the dealer) to fix it they kept assuming bad sensor and ended up changing it a couple time to no avail as it kept the same problem. Unfortunately I still haven't had time to check the sensor readings yet with the banks fully disconnected. Hopefully I'll be able to get to that soon.

 

[THEFERMANATOR]

Check the wiring by your alternator as that is a known problem area, and I believe your boost sensor wiring runs through the loom by there.

 

[rupertalf]

The alternator is in the front passenger side of the engine. The boost sensor is behind there a bit behind the intake, and I have the harness running over the intake horn since I replaced that, so I basically runs almost directly to the wire coupling. But hopefully this weekend I'll be able to get some readings with the Banks disconnected to give some better info as far as what the OBD reader says.

 

[rupertalf]

Ok so here is the live reading from my tool with the banks completely out of the equation.

Engine off ignition on

Live Data
Numbers of DTCs 0
Calculated Load Value(%)0.0
Engine Coolant Temperature(¡£F)181
Intake Manifold Absolute Pressure(psi)17.7
Engine RPM(rpm) 0
Vehicle Speed Sensor(mph)0
Intake Air Temperature(¡£F)64
Air Flow Rate from Mass Air Flow Sensor(lb/s)0.01
OBD requirements to which vehicle is designedOBD
Power Take Off(PTO) StatusOFF
---------------------

Engine on not moving

Numbers of DTCs 0
Calculated Load Value(%)24.7
Engine Coolant Temperature(¡£F)181
Intake Manifold Absolute Pressure(psi)17.7
Engine RPM(rpm) 681
Vehicle Speed Sensor(mph)0
Intake Air Temperature(¡£F)64
Air Flow Rate from Mass Air Flow Sensor(lb/s)0.09
OBD requirements to which vehicle is designedOBD
Power Take Off(PTO) StatusOFF
---------------------

Moving under load

Numbers of DTCs 0
Calculated Load Value(%)82.7
Engine Coolant Temperature(¡£F)176
Intake Manifold Absolute Pressure(psi)17.7
Engine RPM(rpm) 2212
Vehicle Speed Sensor(mph)24
Intake Air Temperature(¡£F)62
Air Flow Rate from Mass Air Flow Sensor(lb/s)0.40
OBD requirements to which vehicle is designedOBD
Power Take Off(PTO) StatusOFF
---------------------

MAP sensor never moved under any change of conditions....

 

[rupertalf]

So with the baro sensor disconnected and boat sensor connected it reads 17.7 psi, but with baro connected and boost disconnected it goes to 7.4 psi. And with both disconnected it read 7.4 still. Any ideas?