Short version there really is none.
Map; Mass; Baro; IAT1&2 are all on the intake side of the combustion process. How your engine inhales. Boost comes from the exhaust side thru the turbo and turns the compressor side of the turbo. As long as the turbo turns you make boost or PSI.

EBP reads the exhaust pressure the exhale of the engine and the restriction of flow thru the cat;muffler and other exhaust components. Exhaust back pressure.
The PCM compares all these readings to see how effective the combustion process is doing and adjust things accordingly.

 

In a nut shell that pretty much sum's it up , Thanks Danny boy for that. Then Other factors come into play SOOT, bad fuel , dirty air cleaner, sensor sooted, sensor failed. Taking the Values of each for Process of elimination.

 

PSI is Boost which is the same as MAP? In addidition to the standard MAP scangauge code (it's MAP that's giving a bad reading) I am using this for PSI

Manifold Absolute Pressure (PSI) (BOOST)

TXD: 07E0221440

RXF: 046285140640

RXD: 3010

MTH: 012203200000

NAM: PSI

MAP is a standard gauge - but this XGauge is actually better than the standard one. It has a larger range which was needed because the standard gauge tops out around 37 psi absolute (about 22 lbs of boost), which diesels have no problem doing. This one should read well beyond 22lbs of boost.

Essentially, I am monitoring MAP with two different gauges reading from the same source? However they both read different at over 24 psi of boost.

Like an idiot I cleared the code and CEL without writing it down as I thought I would remember it.... doh!

 

Ok, having read that again, it says this gauge is better because the "standard gauge tops out at around 37"..... exactly what mine is doing. Doh again...... I think I solved that problem... There in fact never was a problem with the gauge reading.... As for the code and check light, obviously something else. I shall wait until it happens again as all seems well now.

Thanks guys and sorry for any confusion caused but worth knowing that the standard gauge tops out at 37 ish. I wonder how many others have been looking for a problem that wasn't there due to the gauge limitation?

 

Incidentally, the gauge above just shows actual boost (Map less Baro)

 

I thought you were looking at the "turbo psi" gauge on the dash, the 05 should have one.

We learn something new everyday with these trucks. Good to know the standard gauge tops out and defaults, thanks for sharing.

As far as the actual problem you are having, the truck could be going into limp mode. At first I thought it was an overboost condition, not sure how much boost the stock tune will allow. It could also be the oil temp is getting to high. The PCM starts to de-fuel at 250 deg EOT. It would be worth watching EOT on long hard pulls.


.

 

I don't think the XGauge you posted is compensating for Baro, it's just extended range. It's possible to compensate for barometric pressure using the instructions below but as your altitude changes the gauge will be off a little. I'm not sure how much the error in displayed boost would be going over a mountain pass but I suspect it wouldn't be huge.

Manifold Absolute Pressure
TXD: 07E0221440
RXF: 046285140640
RXD: 3010
MTH: 012203200000
NAM: PSI

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
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

So, for example if you got a reading of 14.5 PSI with key on engine off you'd change the MTH to 01220320FF6F and the reading should read 0.0 with key on engine off and would then show how many lbs of boost you were at when the vehicle is running.

If it's exactly right on it should read "0" Key On Engine Off.

 

Thanks. That is the one I am using and it is compensated for Baro. I was watching Baro through the mountains and it dropped to around 13.3 (about 900m above sea level) so would have been around 1.3 psi out.

I think I found the problem, a leaking CAC boot...

Oil temp reached 220 and water 214

 

The Split in the boots are very hard to see you almost have to take them off and sqeeze them It's when you put pressure at them they leak, Glad you found that .

Is this temp towing? and how fast did the temps come back down?( to normal.)

 

Yes, that was towing a 15,000 lb 5th wheel up a 6% incline for a lot of miles. That was the max it reached. As soon as the fan comes on temps drop. Temps drop immediately when load is reduced, back on the level and usually EOT between 194 and 204 and ECT between 190 and 200. Without a trailer, EOT 194 ECT 190 ish. There is generally no more than 6 or 7 degrees between ECT and EOT and usually only 3 or 4 difference.

 

Great that's sound about right with the temps, how did the Boost do this go around with the CAC fix

 

It seems to be fine now. It reaches about 28.3psi with no probs so far. I am back over those mountains in about three weeks, all being well. I shall know for sure then

Next job is oil and filter and coolant change. She is running well and I intend to keep her that way. I have only put about 5000 miles on her. The previous owner said the oil was changed and it was clean. I am using motorcraft filter, CJ-4 and am going to use GO5 coolant, non silicate stuff. This one

Xstream® G05® Antifreeze & Coolant Concentrate : Manufacturer Approved Antifreeze & Coolants : Products Guide : Comma Oil & Chemicals Ltd.

 

Be carful of what you use , I'm not a coolant guy , I have always ran ford gold for the life of My truck, May want to post this and get some feed back from Others

 

I have researched already and this seems to tick all the boxes without the potential silicate residues to block the coolers

 

It's nearly impossible to get Ford Gold in Europe but it came up in another thread, was discussed and is apparently good.