I have a bone stock '10 SS Turbo with nothing done to it. When I NLS from 2-3, all my boost drops to 0 PSI until I let off the throttle, like it went into limp mode. When I get back on the gas, it builds boost back up to 15-16 PSI again like there is nothing wrong. So I start again around 3000RPM and shift right before redline, I hit the next gear perfectly, hear the PSHHH, then immediately drops to 0 PSI and will stay there until I let up and floor it again. There is no CEL. Has anyone else had this problem? Thanks guys.

 

It's starting to do it whenever I shift quickly up a gear, NLS or not and at any RPM. It seems like when I shift up quickly, the PSI starts to go up but then backs down to zero or 1.5. And there is still no engine light. I just checked boost pressure up to 23 psi or so and the whole system is tight with no leaks. Anyone run into this scenario?

 

I've had symptoms similar to you, though it wasn't related to NLS at all since I don't do it anymore. I'd have inconsistent acceleration for a given pedal position, and I could let off and give it the exact same pedal and it'd feel normal again. Sometimes I'd be in boost as well and it would suddenly drop all the boost. It turned out to be the wastegate solenoid on the turbo went out (CEL later came on with respect to the electronic circuit). It had a mid-2011 manufacture date on it too.

Then when I bought a used replacement to get me by for a while, I had an erratic boost and overboost issue with that one.

It turns out both of them had accumulated oily gunk inside them causing them to sometimes stick and not flow air through them correctly. Removing it from the turbo, cleaning out the inside with carb cleaner, letting dry, and then reinstalling it fixed the issue.

It may be a similar issue to my second one if you're not getting any codes.

 

When you NLS you are not supposed to lose the boost, you hearing the bpv is an indication of losing the boost, its supposed to stay at 15-16 psi through out the whole pull, not tryna be an ashole or anything, but how exactly are you doing the NLS ?

 

Well he loses the boost even when he doesn't NLS now, so the NLS part is no longer relevant.

 

SunburstSS, I'm sure I'm doing it right because it worked fine before all this started. Now that you mention it though, I shouldn't be hearing the PSHH sound to the extreme in which I am hearing it... Something's gotta be up with it.

Stamina, since you mentioned the wastegate solenoid, I've been searching around and found others having the same exact symptoms as me! It's dark out now, so tomorrow I'll look into it after work and see what I find. Is it easier to look from underneath or remove the charge pipe and look from above? I have a lift so I can do both if necessary.

 

You can try from underneath. I had the K&N SRI, so I just spent the two mins popping that off and then I just reached down from there to the turbo.

You'll need to be good with pliers to slide those small hose clamps off the 3 places where it's connected via hoses. I'd recommend sliding off the ends where it connects to the turbo and the wastegate solenoid can. It's easier to disconnect from there IMO as it also means when you pull it out you can inspect the hoses for tears, kinks, or clogs. Don't forget to unto the electrical connection by pressing on the metal wire on the side of the harness and pulling. The solenoid has a long plastic hook that holds it in place. Sliding it away from the firewall is the correct direction to unhook it.

I sprayed the cleaner real good up into all three ports. I ended up having oily residue on the straw and dripping out of the solenoid, so apart from it fixing my problem, it adds to the evidence.


Edit:
Here's a picture I took during my swap that might help you visualize...

The side facing you in the picture is facing the turbo, with the hook at the top, hooking in the direction of the firewall. The hose at the right comes from the pressure/boost side of the turbo, the bottom ones goes down to the wastegate can, and the one on the left goes back to the unpressurized side of the turbo.

 

Thanks so much for the photo and info, Stamina. I got the actuator out and tested all the ports with power going to the plug. The plunger works perfectly and strongly. No leaks and it was as clean as a whistle. The lines attached were free and clear too. What else could this be?

 

I just buttoned it all back up after cleaning everything. Took it for a drive and it still did it, so I let up from full throttle for a split second then floored it again and boost went right back up to 15psi. It's like the computer doesn't like hard shifts. I did NLS at 4250RPM and chirped the tires and it held boost fine though into the next gear. Weird huh?

 

Just so everyone knows, it ended up being a faulty MAF causing the weird problems. A new one has been put in and everything is fine again. NLS is strong with no hiccup in power or boost at all. Thanks guys for the recommendations and replies.

 

Faulty maf and still no CEL? I am having similar symptoms with no cel now also.

 

The symptoms started happening without a CEL and lasted about 2-3 weeks before I got a p0100 and p0102 simultaneously. At first I thought it was the harness but that checked out fine. The MAF was acting weird on the scanner so it was replaced and I haven't had any problems since.

 

Thanks!!!