turbo de-boosting?

[jetjock15]

Weird one but I did a google search and found many people experiancing the same problem, but nobody posted a fix.

The deal is towing heavy, level to slight uphill, only in OD or maybe one gear below, about 55-70 mph right about 2k rpm my turbo was de-boosting

So I would be going along normal, all good, 2k rpm 25 psi boost, 950-1000 EGT, steady state cruising, then once in awhile, always in the same general parameters listed above, the turbo would wind back, which i could hear and on the boost gauge it would drop steady right to 15psi and hold, the EGT would immediately start climbing, up towards 1300, could not feel any real loss of power, and then when the EGTs got to about 1300, the boost gauge would rocket up to 34 psi and hold for about 2 seconds, then settle back at 25-28, and the EGTs would come back down, and all would be normal until the next time.

Like i said i found others with the exact same issue, but nobody posted a fix. It sounds like an EGR issue maybe, but My setup right now is gogo intake, where there is no separation of the intake for the EGR, the valve just sits down in a huge hollow empty intake, and my Tow Tune has it "programed" off also. So I dont know, weird. Besides that the truck runs fine, leaks nothing. I am going to try to just unplug the egr valve and see if that does anything, I only had it plugged in cause I have heard of dudes having less power unplugged, but I will try it. Then after that I am going to go back to stock tune and see if it does it. I tried loading two different towing tunes I had though, and it did it on both. Any thoughts? thanks guys.

[PGreenSVT]

What were your EOT and ECT while this was happening Rob?

[jetjock15]

about 220 ECT and 235 EOT, not too bad. Its not de-fueling at those temps, which was my original thought, and the fact the EGT immediately starts to rise, and I feel no loss in power, she is not retarding the fuel input, for some reason the turbo veins or control just decides to jump around. I dunno, like I said, I will unplug the EGR next.

[DELTAJOHN]

I was pulling my 8K trailer up a long grade a couple of days ago, I held 23 lbs boost, 2500 rpm no issues, my ECT to EOT was 205 to 214, my boost held there as long as I had my foot in it.

[bismic]

Later calibrations will deboost around a 15 degree delta between ECT and EOT - depending on power input (ie heavy towing).

With your intake and an external oil cooler you clearly have no issues at those temps, unless you have a calibration that thinks there is an issue.

That being said, when was the last time the turbo was off for an internal inspection/cleaning?

[U235a4]

Originally Posted by bismic

Later calibrations will deboost around a 15 degree delta between ECT and EOT - depending on power input (ie heavy towing).

With your intake and an external oil cooler you clearly have no issues at those temps, unless you have a calibration that thinks there is an issue.

That being said, when was the last time the turbo was off for an internal inspection/cleaning?

that was my thoughts.

What is your strat??

[Evil Eye]

I am immediately suspicious of the EGR valve (thinking that the backpressure may have forced it open), but thought the EGR portion of the intake was removed for the Gogo setup...

PS. I believe that the temp delta also takes into account the LOAD% that is on the engine...

[U235a4]

it would be interesting to have AE hooked up when this is happening to watch a few pids

[jetjock15]

Originally Posted by Evil Eye

I am immediately suspicious of the EGR valve (thinking that the backpressure may have forced it open), but thought the EGR portion of the intake was removed for the Gogo setup...

PS. I believe that the temp delta also takes into account the LOAD% that is on the engine...

ya, the valve is there, but the entire thing sits down in a fully open hollow intake, so if it is open or closed, it not re-directing boost/air anywhere, gogo just gives the option to leave the plug port, and I took that because others have reported loss of power when egr was totally removed, its there just to make the computer happy I guess. I will try to unplug it.

[jetjock15]

Originally Posted by U235a4

that was my thoughts.

What is your strat??

I buy the delta things, at times the ECT was probably lower and the EOT was hotter, so the delta was bigger, means nothing with my separate systems, but the computer does not know that.

I can check my strat, but I did find various years 6.0s that had posted with this same problem on different forums, but nobody closed out the threads, they never fixed it, or they never posted the fix.