RugRunner

Just had a GIAC tune put on my 2007 Turbo today…installed by GIAC certified dealer. Original owner had a GIAC tune put on in 2007…now I got the updated version installed. On the way home (approx 82 degrees outside), any time I'd go WOT from a low RPM (around 2k up to maybe 4.5k), I would get a quick bit of what sounded like a metallic rattle/snap…just one or two, less than half a second…at the moment the turbos really spooled at the power hit full on hard. Nothing more the rest of the way up. Not rpm or gear sensitive…just has to be at WOT and listening at the moment the power hits. Almost like something metallic was loose. Happened maybe 5 of the 6 times I went for it.

Took it out again after dinner, 65 degrees. No metallic rattle sound, now its more like a single whip crack, right when the power hits hard at WOT. Nothing more under any other circumstances including open rev up to about 3.5k in my driveway. Happened maybe 1 of every 3.5 times I tried to replicate it.

Seems to run good otherwise. No CEL. Pulls hard, even harder when the temperature outside dropped. Idles nice and smooth. 29.5k miles on car. Has cats, headers, Fabspeed exhaust.

Video attached…any thoughts on what it is?

TT Surgeon

Hard to tell, might be a boost hose leaking?

RugRunner

I feel like I'm making a lot of boost at the start and all the way through. Will monitor. Thanks TT!

TT Surgeon

Listened again on another computer, I'm sure you have a loose boost hose probably by the IC. Good luck.

CincyScott

Probably not needing to be said, but let's stop winding it out until we find the source of that issue . If it is a boost leak, you can over spin the turbo and damage it.

If you are the DIY type, you can build a cheap pressure tester unit to pressurize the system and find the leak. Otherwise your mechanic can do that just as easily. Don't rely on the the "smoke test," as they usually are not pressurized enough.

Good luck!

4ocious

Cheap malfunctioning diverter valve?

RugRunner

It shouldn't have any sort of aftermarket diverter valve. Fwiw, it doesn't do this every time...just maybe 25% of it and only if I'm WOT and have (at least that I can tell) Sport Mode On (it's a Sport Chrono car).

aa909

In sports mode are you gettin consistent over boost (17+) registering on the digital boost meter when you WOT? If so then I would guess you don't have a boost leak.

RugRunner

I'll have to go out and check. I feel like I am...and I was prior to the tune. Will advise.

aa909

Get on the freeway in 4th, and while cruising at 3K RPM floor it. You should see 17psi with an up arrow. If you're getting that reading then I would imagine you don't have a boost leak. Good luck

4ocious

OEM valves are cheap plastic.

TT Surgeon

I still think it's a loose hose on the IC, will only manifest under load at wot. The dv's on a 997tt are not nearly as failure prone as the 996 variety.

TypeRx

I had a semi-similar problem recently on my GIAC-tuned 997TT -- ended up being the hose/adapter fitting that connects the charge pipes to the throttle body. I took it off, cleaned the inside thoroughly with soap/water, sprayed some hairspray on both ends, and replaced both clamps with heavier duty ones. You have to make sure to get the fitting on perfectly "square" on the throttle body and that the clamps tightening bolts are on the right spots (they are marked).

rob.boost

Also, run a log. It very well could be your FPR line disconnected at either the FPR side or like me at the manifold side. If your short terms are maxing out under full load (25%) to compensate, then that is your problem.

MK_TT

^ good point! I did not think of that, always a good habit to check it every couple months.

here is the FPR side:

https://www.youtube.com/watch?v=ydEe...ature=youtu.be

Kyle check that as well as your intercooler lines / and TB y-pipe connection up top