turbo pressure jumps around

[jetjock15]

just did a big towing trip to test out the new stud job, gogo intake, egr delete, etc...
Engine ran great but I did notice one thing I hadnt before, but I assume its from the new "studded" aggressive tow tune I am now running. My turbo boosts as much as 32psi at times and can hold constant for long time, so I dont think i suffer any leaks in the turbo/pipe connections.

However, it one certain spot, when im towing up a slight grade in OD, like 1900 rpm, where it is kind of luggin an slowing down from 65 to 55, still in OD at the spot, where if i pushed the gas pedal down it would downshift, but without that it was holding OD for a min or two, anyway, without anything else changing, the EGT was at about 1000, the rpm right at 1900 the trubo would boost to 30psi and I could here it whine louder, it would hold for about 20 seconds then the boost would drop right to 15 psi for about the same amount of time, then boost back to 30psi etc.. did that for about 3 cycles before the truck hit about 55mph and downshifted then the boost went high, and constant...

Anybody see anything like that before?

[WarChild]

Did you check for.codes? Mine use to.do something simular to.that when my egr valve whent bad.

[jetjock15]

i just put in gogo intake, with egr delete. I put egr valve back in, and left it plugged in, though the tune has it programmed off too. The gogo intake comes with a EGR cover and gives you the option of removing it altogether, make i should try my next tow with it unplugged.

[Lilpooh]

What are you using for gauges? Sometimes when the analog boost gauge is tapped into the MAP hose, it will cause the gauge needle to flutter.

[jetjock15]

All my gauges are autometer, boost is tapped into the elbow. I could hear the turbo whine increase and decrease with the change in boost. Was not a flutter type event , I would drop from 30 to 15 for about 10 seconds then boost back up. I wonder what defueling looks like? Maybe it was a safety thing? EGTs only 1000 but oil temps were high

[jetjock15]

If i didn't mention before, towing 15k, no change in power occurred during the cycle of 15-30 psi

[WarChild]

High oil temp defuel is at 250. What was yours at? My money is.still on egr valve. Did you check for codes?

[jetjock15]

no codes that the SCT could read. Oil temps were high, but I have been there before and not seen this. Egr issue, or just normal, I found a couple posts via search where other people have reported such occurrence. I dont know. Like I said, no loss of power, so I guess im not to worried. Next time I tow i might try it with the egr valve unplugged.

[Evil Eye]

I took a video of mine and mine was definitely turbo surge. Did you get an aftermarket turbo with your new goodies? I ended up need new tunes, which fixed the problem. Yours may be due to the intake and intercooler flowing more air. You might need to have your tunes tweeked.

LINK

[jetjock15]

thanks for the video Evil, that is definitely turbo surge ( my 7.3 did it until i got an ATS turbo). That is not what my truck is doing. Mine goes to a stead 30 psi for 10 seconds, then i hear the turbo spin down and the boost goes to 15 psi, very controlled, and stays there steady for 10 seconds, then spins back up to steady 30psi as I hear the turbo spool back up for 10 seconds. repeated 3X, no loss of felt power, only happened under the condition described above, any other circumstance all normal.