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Discussion Starter · #1 ·
Hey guys, i posted this issue awhile back and only got a few replies and my problem has no started to escalate.

I am driving a 2006 f250 2wd street tune(sct X4) just switched to Rotella T6 5w-40

(no column gauges, just working off the gauges from the X4 and the stock boost guage)

Im having an issue i cant quite pinpoint.

I had just done the Oil cooler replacement to a heavy duty model. while i was in there i went ahead and welded the egr cooler shut and did a bath on the intake to remove a scary amount of carbon that had caked up in there. before all of this the truck ran amazingly and had PLENTY of power aside from the issue of dumping oil down the back of the motor from the blown oil cooler gasket.
Here's where the issue comes into play. after the better portion of 2 weeks of waiting on parts and slow working on it i got it all back together and in ran rough momentarily but smoothed out. noticed no major issue until i began driving it. At first i had very little power, high boost pressure, and a louder whistle from the turbo that i attributed to welding the egr cooler shut causing more exhaust pressure feeding to the turbo from the Y-Pipe. After skimming the forums on here i managed to ascertain that it could be that my vanes in the turbo were stuck and decided to tackle taking it apart to clean it. After the first cleaning done hastily before work later that day i put it back in the truck and it changed nothing and now i had noticeable turbo farts (Thwaft, Thwaft, Thwaft) after releasing the throttle from 10.

Throttled it over and over that night seeing if i could blow out any excess build up to no avail.

This brings us to now. I had the turbo out and apart again, extensively cleaned the vanes, pulled and replaced the vgt solenoid (which was my next suspision) as well as pulled the plunger, cleaned it out, re-indexed and replaced. even after reassembly of the turbo i had clean movements of the vanes as controlled by my magnet stick stuck to the plunger for the vanes. Cleaned the EBP sensor and tube, it was fairly coked up. and reinstalled. boost pressure seems to build normally as it used to instead of boosting to 30+ PSI straightaway at 15MPH, however I am still left confused as I am still not experiencing the power and bottom end i know the truck is capable of. my next step is the MAP sensor check as i know the tube is clean and connected well. I've put a lot of effort to not come onto the forum with my first issue being a silly one so I have tried everything i can think of up front.

A few weeks have gone by and my terrible fuel mileage has become a burden. Once i replaced my EBP sensor i was getting the same readings as before on my (SCT X4: 58-60 psi at idle up to 100+ psi when on the throttle) however even though it read the same as the stock sensor my turbo no longer jumps up to 30PSI as easily.

Here is where the serious problem comes into play that has gotten worse, I replaced my map sensor as a test, no change, finally i put a THIRD VGT solenoid into the turbo now my VGT commanded cycle will start out at .65 when i start the truck and within about 30 seconds it will drop down to .15-.18 and stay there, with every VGT solenoid i have replaced this problem has gotten worse and if you even touch the gas pedal you will max out the commanded position of the vanes (open).

I will try anything you have any ideas for i have run out of ideas entirely. I am to the point that in the next coming weeks i will pull up the intake yet again and check and see if my welds over the openings for the egr cooler have swelled up or anything. i have no idea at this point what could be causing it, i have called diesel techs and they said they havent seen this particular issue. PLEASE HELP

Please let me know anything that could help and I am more than happy to post any data needed to help me figure out the issue.

MUCH appreciated guys.
Skyler.
 

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Weird.

A few questions: Do you still have your catalytic converter? Did you cut the little scoop out of your up-pipe when you did your EGR block? Any codes?
 

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Discussion Starter · #3 ·
Weird.

A few questions: Do you still have your catalytic converter? Did you cut the little scoop out of your up-pipe when you did your EGR block? Any codes?
stock CAT and Muffler. i did not cut out the scoop in there, didn't know it was in there until after everything was back together but many people who had done it before said they didnt have issues when they left it in. i tried pulling the cat and muffler off and ran it for days like that and it didnt change anything. same EBP readings, same everything.
 

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When you delete egr you do get a slight lag on take off.


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Discussion Starter · #5 ·
When you delete egr you do get a slight lag on take off.


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this is WAY more than a lag off take off. my vanes arent stuck because i can hear them change tone if i unplug the VGT or EBP sensor and let them default. but the vanes are actually being COMMANDED by my ecu to always stay open. I cant figure out what is making my computer tell them to always stay open.
 

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Got it. Still interested in codes.

Also... Are you sure that your VGT solenoid is actually moving in response to the changing VGT command signal (i.e., properly connected)? When work like what you did is done, the harness gets yanked on. Harnesses don't like getting yanked on. That means that any commanded signal is suspect.

________

Edited to add...
When I started typing this message, those last two messages weren't there. Just fyi...
 

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Discussion Starter · #7 ·
currently i have a "Turbo control no signal code" because i tried running for a bit with the vgt unplugged and got no change.
the relevant code is the P0299 turbocharger underboost.
 

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Discussion Starter · #9 ·
You changed the map. Did you change the hose?


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hose looked good but i did pick up a new hose to throw on it today that i plan on testing tomorrow. but both MAP sensors put out the same reading about 14.5 KOEO i believe which if i recall is right about in the normality range.
 

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So, no sensor out of range codes or anything like that? ...and you are sure that your exhaust connections have no leaks?

The EBP replacement sensor is Motorcraft, yes?

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Sean keeps getting those questions in after I start typing. Lol.

He's the pro here, btw. Follow his lead.
 

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Discussion Starter · #11 ·
So, no sensor out of range codes or anything like that? ...and you are sure that your exhaust connections have no leaks?

The EBP replacement sensor is Motorcraft, yes?
No sir no other codes. fairly certian i've eliminated any exhaust leaks, i tested the joints and trouble areas with aluminum foil around them. there is damn near no soot on anything. i could have eaten off the aluminum foil after driving with them on the exhaust for a week. EBP is defined as exhaust Restrictions rather than actual "backpressure" and if there was a leak it SHOULD cause the system to command the vgt more closed to help build "backpressure" when the system fails due to the leak to my understanding.

And yes, both sensors are MC
 

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Did you reinstall the metal gasket on the bottom of the intake where egr cooler bolts up?


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I agree with your interpretation. The problem is that - when things get weird - it could mean that there may be more than one issue. ...and that makes the linear analysis much more difficult. So bear with me if the questions seem to bounce around a bit.

I was a bit surprised that you didn't see a difference in EBP when the cat and muffler were disconnected. That was part of the motivation for asking if the EBP sensor was Motorcraft.

I may stand down now to watch where Lox goes with this. I'll be lurking and thinking, though.
 

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Discussion Starter · #16 ·
I agree with your interpretation. The problem is that - when things get weird - it could mean that there may be more than one issue. ...and that makes the linear analysis much more difficult. So bear with me if the questions seem to bounce around a bit.

I was a bit surprised that you didn't see a difference in EBP when the cat and muffler were disconnected. That was part of the motivation for asking if the EBP sensor was Motorcraft.

I may stand down now to watch where Lox goes with this. I'll be lurking and thinking, though.
HOWEVER bear this in mind, like i said all i have currently is the (SCT X4) which i have heard reads EBP entirely wrong no matter what and i havent found an accurate enough and reliable amount of people all agreeing in the formula for sct's ebp interpretation. let me know what you think of that. however i will say that dropping the cat and muffler makes it sound MEAN.
 

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Ebp reading on sct is complete . Dunno what they were thinking. Unplug the sensor and see if it reads the same. Also check my above comment about CAC


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I'll just add in that you may want to throw a Bluetooth OBDII reader on order. That, a cheapo Android tablet, and Torque Pro app are great for background diagnosis.

I completely get people wanting SCTs and the like for daily driving. ...but - when the going gets tough - things like good EBP readings matter!

Now back to Lox!
 

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Discussion Starter · #19 ·
Ebp reading on sct is complete . Dunno what they were thinking. Unplug the sensor and see if it reads the same. Also check my above comment about CAC


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thats one of the things i dont understand. i have heard of people having the issue with sct reading 60 at idle and going up from there but them not having the same vgt issues that i am having. and when i unplug the sensor the sct reading drops down to 21.5PSI interestingly enough when you do this the COMMANDED vgt cycle acts fairly normal however when you put any power behind that the vgt and the transmission both have issues because it stays at the default 21.5 which it should not be at 21.5PSI WOT in normal conditions.
 
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