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Ok i've searched for an answer and can't find one. So here it goes.
2004 6.0L 18,500 miles...Running SCT w/ aggressive street tune for approx. 7 months. Last couple of days when the truck is warmed up and i'm on the highway at or above 55 the truck stops making boost and the egt's shoot up to about 1300 -1400 if i stay on the pedal. And if i slow down enough by applying brakes the torque converter unlocks and then the truck will build boost again if i get back in it.
No CEL no other issues other than a slight surge from time to time at a constant speed of about 35 or under. But that goes away after 30 to 45 sec. I use Stanadyne on every fill up and have even loaded my other tunes (ultra comp and a tow tune) and also put the truck back to stock all with negative results. I plan to take it in for service but can't for a couple weeks...any ideas would be greatly appreciated. I will buy the parts myself and install but just don't want to start throwing parts at it without knowing.
Does this happen right after you get out on the highway? ie right after you heavily into the throttle and then let out of it.
sometimes but not necessarily. it will do it after driving in overdrive for a distance...when i want to pass and i put the pedal down it sometimes will not boost and egt's just climb.
it sits for a couple days (2 or 3 max) at a time but when i do drive it i run it hard. i purchased it used...jan. of this year and it had 13,000 on it then and since jan. i've put the 5,500 miles or so on it.
Bernie, this sounds like a pretty classic case of the VGT vanes in the turbo sticking. I would get the dealer to take a look at the turbo operation and EBP sensor.
i have found too that when the boost pressure drops and the egt's rise, that is more of a boost problem than a fuel related problem. you could have a cracked I/C or tank, or even a boot that has a crack in it, and at certain boost pressures when it's warmed up maybe it opens up, allowing the boost to escape, now you are still cramming tons of fuel in there, but without the o2 to burn it, you are in a rich condition, explaining also the high EGT's
lvtitan, thanks for the reply. i plan to get it into the dealer next week so i'll let you guys know what they find.
Thats just what mine was doing (04 with 77K) it also did the cha cha cha noise under throttle some times. It was the turbo that went, along with some injectors.
Last edited by Slammedsi; Sep 16, 2007 at 08:34 PM.