Ok so I pulled my map hose off yesterday because I have been struggling with a low boost issue. I didn't find any cracks or holes. What I did find was that the little spring clamp wasn't tightening the hose down tight enough. So I moved it up so it clamped on tight. Seemed to fix the problem. Turbo spooled up a lot faster and seemed to build more boost. Thing is I cant tell because my scan gauge II shows -11.5 lbs of boost all the time now and now I have a p0237 code. And it started rolling coal like the thing has a hot tune in it. I think I will pick up a new MAP sensor tomorrow. Any help would be appreciated.

2003 F-350 egr delete, Atlas 40, 4 inch straight pipe. No tuner.

 

https://www.ford-trucks.com/forums/1...her-p0237.html

 

I believe map, baro, and EBP are all monitored by the PCM, it does some math with those numbers to come up with the boost value.

So it reads -11.5 all th time like key on engine off, idle, and under load? I'd double check the electric connector and harness to the map first.

Scan gauge's regular boost gauge kinda flips out over 22.5psi and reads negative numbers so it's probably seeing high boost even though the reading is negative. There is a "tunable" boost gauge for SGII that can be adjusted for baro (altitude) and it doesn't flip out when the boost goes over 22.5psi.

Boost
TXD: 07E0221440
RXF: 046285140640
RXD: 3010
MTH: 012203200000
NAM: BST

With a little tweaking you can adjust this to read boost.

To do this, just plug in the MAP code - get a reading from it with the key in the on position but the engine off, then based on the reading changed the last 4 digits of the MTH to whatever corresponds to your reading on this table

14.0 -- FF74 (I USE THE "FF71" FOR MY AREA, IT WORKS GREAT)
14.1 -- FF73
14.2 -- FF72
14.3 -- FF71
14.4 -- FF70
14.5 -- FF6F
14.6 -- FF6E
14.7 -- FF6D
14.8 -- FF6C
14.9 -- FF6B
15.0 -- FF6A

 

Look at the MAP setting in your SG2, that is the actual value it's reporting to the PCM. At sea-level, normal atmospheric pressure is 14.7 PSI. So, that is what the MAP should be showing (give or take a few tenths based on your altitude and local weather).

How the PCM controls the turbo vanes to maintain boost is way more complex as indicated above, using EBP (unless you have an older strategy that doesn't actually use EBP, and perhaps EGR setting as well)..

But, for the SG2.. watch MAP on your SG2 you'll notice it rises with BOOST. Ta da. BOOST is the MAP reading minus 14.7 (the default formula). At higher elevations you can use the math adjustment to compensate for your slightly lower normal pressure..

 

Yep all the time, koeo, idle, and under load numbers don't flinch. I do have that boost gauge installed in my scan gauge and it has always worked until yesterday. I runs like it has never ran before now that the hose is sealing up, but my goodness the smoke on take off is horrible. I'll see if I can post a video clip of it.

 

Ok just went and got a couple numbers.
Baro is 14.2
Psi is -11.1 (I think this is manifold pressure)
Boost is now at 0.0
All numbers are koeo.

Went for a short ride down the road psi and boost never changed.

 

Remove the MAP hose from the manifold and make sure the barbed fitting is free and clear of soot. If your not seeing pressure on the gauge it's either plugged up or the hose has a hole but you should see a little bit of a reading.

 

Code P0237 is set when the MAP signal is lower than the specified value for a length of time set
by an incremental counter. This code is used to detect a MAP circuit that is open or shorted to
ground

 

I checked the wires in the harness and can't find anything that looks bad. I'm thinking the the sensor has taken a crap. I've unplugged and plugged it back in a few times wiggled the wires and nothing changes. Hopefully I can get out of work on time to pick one up tomorrow. Thanks for the help.

 

I agree try a new sensor its failing the baseline test @ KOEO

 

Put a new map sensor in and took care of the problem. No more smoking and boost readings are reading like they should.