I have been fretting over my boost being limited to around 18psi no matter how hard driven. I spent a lot of time troubleshooting and at the end ,same boost, but the truck is now running in regular driving maybe as good as it was when new. So towed my 10K boat and on longer bridge ramps I got as high as 28psi and would hold 25-26. I guess the “problem” is solved since towing is my main concern about boost. After reading all the online info or opinions I could find, some said 18-20 was all these trucks make, some said they needed more load to make boost and most seemed to say that they could easily make 26psi any time during hard acceleration. So, I am still at a loss to understand this but it’s just academic now since I’m fine with 18psi just for driving around. I thought this might be helpful to someone like me trying to fix a problem at didn’t need fixing.
My attention is now on the cooling system. Since I bought a monitor for boost issues it lead to discovering temp delta issues and a lot more things that got my truck to a better place. But that is for another post as now nothing is critical temp wise. Just want to say that I had no idea what was really going on using the dash “gages”.

 

I see u replaced the hot cac boots. Are they still clean looking ( no oil stains)? What about the cold side, do you have boots or all plastic? are they clean boots? If any cac boots are oily replace them. If plastic, remove and look for cracks. Replace if needed. I'll leave it to the wizzards to chime in on the turbo if need be. If I did my research right, normal boost is 0-26, severe is 27-28 and alarm is 28.

What is your temp delta? Should be 12ish fully warmed up and runnin down a level highway

I set my Edge for the following alarms:
Battery 13v
FICM 46.5v (norm around 48)
ECT 215 (norm is 190-200)
Boost 28 psi
EOT 230 (norm is 200-215)

Some other alarms you may or may not be set with your Edge:
fuel pressure 45psi (norm is 50-60)
EGT (pre) 1300 degrees (norm is 650 - 1200)
EGT (post) 1000 (norm is 700)
oil pressure 7psi (norm is 12)
coolant pressure 16 psi (norm is 10-12)
Edge does have an EGT sensor and I shut down my engine at 312 degrees

I think injector pulse width should be 0 with key on/engine off
990 low idle
660 high idle

There are probably some others out there and maybe new thoughts, These are my notes from searches done a few years back

 

Thanks, my "extensive" troubleshooting of boost issues included leak testing, all boots including the new ones are OK. I am done with worrying about boost as the boost is there under towing loads. I would like to understand why boost is available only heavy towing load going uphill. I think it may have something to do with inferred EBP as the inferred number is too low, i'm not sure the inferred number that I see with Edge monitor or with Forscan is what the pcm is using but later on, I will work on that.
My delta's decent now after the new cooler, usually runs about 9 cruising while ECT is 192-194. However I think I am on the edge of ECT issues as while towing with the 10K load at 62-64 mph it runs 216-218 range with ambient about 90. I goes up to 220 and even 225*228 range too easy on long bridge rams (Mississippi River). Fan doesn't seem as active but at 220 it starts to intervene. I am going to get some forscan numbers on all of that later.

 

Whens the last time u changed yur thermostat?

 

Not sure of what all would make an '03 different for max unloaded boost versus my '07, but just to chime in: I can hit 26 - 27s unloaded under heavy acceleration. During the VGT relearn after work was done, I got as high as 31s, but it slowly came down. Try finding an empty on-ramp to the freeway and set your gauges (whatever you are running) to capture max on the boost and on a rolling start hammer the throttle and don't let off (well until you get into 70s). I just did that a few weeks back and hit 27.5, on a rural highway closer to home hit 26.2 (was rolling faster when I hit it and backed out sooner). Good enough for me...

 

I didn't go into detail about "extensive" testing, but I did what you suggested and held it to 85+, did hills, ramps. I logged the data and have way too much paper, pretty much every pid that could be in play. Since it is a MY03.25 and it is inferred EBP, extra attention was given to the MAP and MAF. What I have now, I can work with but mostly curious. From your signature it looks like we have been down some of the same paths.

Strider, it was changed when I flushed it before the oil cooler in maybe this February. Old one ran the same, just changed for PM. As for cooling, I am planning fin cleaning on rad, a/c, intercooler. and maybe a water pump at that time. Water pump is original I think ( can't remember for sure), I will also get some data of fan speeds ect.

 

I do agree with the loaded/unloaded difference. My truck can chit it and git it with only about 20 psi boost on a factory tune. Loaded with about 8k, 25 easy. Running a tune I'll get 25ish unloaded.

 

Also my fan doesn't even break 700 rpm until probably 220 ect. It hasn't hit that high since HG though.