Ok, on the left side of the engine you will find a switch that has wires going to it, this switch has a tube connected to it that goes to the exhaust manifold. Its called EBP (exhaust back pressure) switch, remove to switch, start the engine and see if exhaust flows out this tube, if not the tube is plugged and that is you problem, clean it out or replace it.
If you had a scanner with live data you could watch that PID and see what is going on also. This is the first thing I would check.

 

Ill take it apart and check it out. I don't have a live scanner yet. Just dont see how cycling the key would remove limp mode from truck but I do know these 6.0 work weird

 

A ScanGaugeII is a great little set up. I am amazed at how much it does , it can see just about everything on a 6.0 engine. You should get one for monitoring the engine coolant temps and oil cooler temps if for nothing else.
The EBP is what the pcm uses for adjusting the vgt values for the turbo.

I am a bit suspect that your ICP or IPR may be the cause of the thing being in limp mode when you first start it up. May have crap piling up on IPR and shutting off the engine gets it to drop away and reposition when you restart it second time ???
Of coarse a ScanGaugeII will allow you to monitor the ICP and IPR values. May be a good time to pick one up. Auto Zone has them on the shelf for $160.00 and it will be the best money you will ever spend on the truck !

 

Yah I may need to because I just removed my Ebp line and sensor out after work tonight and it was clean. No clogs nuthin. of coarse I cleaned the line out since I had it removed but wasn't necessary

 

What icp and ipr values such I be looking for iam going to go pick up a scan gauge tomorrow.

 

Having the same problem. My baro is not corolating with my map. Baro reads 81kpa from what I remember when it should be reading 97 or 103

 

You cycle your key and it runs fine?

 

Nah, I have a tune and her and when I'm around 50-65 I can feel a major lag before my turbo spoils and more smoke than usual. I just noticed it one time, happened almost a year ago but that's the only problem I have. Been trying to track it down for a while.

 

Yea mine does that frequently. Done pulled whole engine apart to figure it out

 

The only thing I can think of is that's left is the PCM/ECM. I was reading that it also has a baro sensor built into it. I did switch my PCM when I was doing some trouble shooting for another guy and my truck sounded different but I didn't think about checking the data.

So far I have a new baro sensor (one under the setterint colum), a new map sensor, and turbo was cleaned almost 30k miles ago but has been tuned since then. Also could be a problem with the VGT solenoid, but I've ran her on the boost test and it cycles fine. I have 99k miles on my truck right now.

 

You need to get a scanner that reads live data and your EBP, MAP, Baro sensor should all read the same at key on. Levels depend at what elevation you are and sometimes reading will be different because one is being displayed in PSI and the other in KPA. Make sure to convert them so they are all in the same measurement.

 

I would also advise on checking to make sure your FICM is putting out 48volts
And your injector o-rings could be work and not sealing till your truck warms up, depends on how many miles your truck has.

 

I've installed a new map sensor. And cleaned out my turbo/veins/ring. Only reason I don't think it's injector o-rings is even if I don't let it warm up I just start it shut it off and restart it it's fine. No more limp mode. No like it's in limp mode till warms up nd then it's good. I do need to get a live scann but with a girlfriend you could imagine where the money's want to spend on my truck usually goes. I do appreciate all your guys help tho. Is there a way to test the Baro sensor without getting a live data gauge? Wish my cummins insight program would work. Lol

 

I suppose if you found the resistance specifications you could test the sensors resistance. Or the output voltage from the harness.

Some advice, dump the girlfriend. I'm young too and I have 3 projects, no damn time for girls haha or money!

 

Lol I feel ya. Cannot have sex with my powerstroke though unfortunately I've tried lol.

 

Haha

Well I just had my turbo super lag on me today and instead of black smoke it was almost brown. I'm thinking my VGT solenoid is clogged from the flex oil feed line deteriorating

 

Yeah I just bought a unison ring off a buddy of mine and will be replacing my Vogt selenoid soon. Hopefully that'll do the trick. Either way I still drive it. Just dont want to start my truck shut it off and restart it every time I get in it

 

Did you ever get the chance to run a live data scanner on her?
I just finally found out its my PCM, it's bad

 

Just picked up a scan gauge II. The other day. Right now I have ficm voltage at 48-48.5 at all times. Icp any where from 650-710 at idle and ect/eot difference is about 20 degrees when driving. Lol oil cooler time. So now that I have a scanner. Should I be monitoring icp?