I posted this over on duramaxforum but haven't really gotten any suggestions
so here goes...
I recently just bought a 2008 LMM. It has 98k miles on it and was completely stock when I bought it. I checked balance rates as soon as I got it home and they are all within +/- 1, it holds rail pressure perfectly, the turbo built boost just fine according to my CTS and it drove just like a stock lmm, no issues what so ever. A week ago I put on a 5in straight exhaust and EFI Live from a very good local tuner here in Hewitt. My issue now is the truck will hesitate when accelerating, it doesnt build boost and both desired and actual rail pressure spike, drop and pick up again, once it gets through the hickup, the turbo starts building boost. It does not do it consistently and it does not matter what RPM or speed I'm at. it seems to do it worse when rolling into the throttle and will get through it quicker or not do it at all when a simply push the pedal to the floor. And sometimes it will get stuck in this spot where it wont build any boost over a few psi until I let out of the throttle and down shift. Also, while at a constant speed the turbo just slightly surges about 2 PSI. it idles perfect and is not making any weird noises other than the surge at speed.
I'm getting no codes and I've checked all major connections. I just did a leak test and can't find any leaks in the boots or intercooler as far as I can tell.
I'm pretty much stumped. I'm assuming the turbo is about toast but before I drop atleast a grand on a new one I am open to any suggestions anyone has. I've been reading that without the EGR blocked it can cause weird symptoms. But I am just out of ideas at this point. Has anyone come across this issue with just an exhaust and EFI?
And before anyone asks, It is not the tunes, I think...
so here goes...
I recently just bought a 2008 LMM. It has 98k miles on it and was completely stock when I bought it. I checked balance rates as soon as I got it home and they are all within +/- 1, it holds rail pressure perfectly, the turbo built boost just fine according to my CTS and it drove just like a stock lmm, no issues what so ever. A week ago I put on a 5in straight exhaust and EFI Live from a very good local tuner here in Hewitt. My issue now is the truck will hesitate when accelerating, it doesnt build boost and both desired and actual rail pressure spike, drop and pick up again, once it gets through the hickup, the turbo starts building boost. It does not do it consistently and it does not matter what RPM or speed I'm at. it seems to do it worse when rolling into the throttle and will get through it quicker or not do it at all when a simply push the pedal to the floor. And sometimes it will get stuck in this spot where it wont build any boost over a few psi until I let out of the throttle and down shift. Also, while at a constant speed the turbo just slightly surges about 2 PSI. it idles perfect and is not making any weird noises other than the surge at speed.
I'm getting no codes and I've checked all major connections. I just did a leak test and can't find any leaks in the boots or intercooler as far as I can tell.
I'm pretty much stumped. I'm assuming the turbo is about toast but before I drop atleast a grand on a new one I am open to any suggestions anyone has. I've been reading that without the EGR blocked it can cause weird symptoms. But I am just out of ideas at this point. Has anyone come across this issue with just an exhaust and EFI?
And before anyone asks, It is not the tunes, I think...
