Tapping/pinging noise under accelleration, third time in for service, still not fixed
 

100% stock 07 auto GT

on the 2nd and 3rd gear upshifts under part throttle i get a tapping/clicking/pinging noise briefly
it will happen if i got WOT at highway cruising speeds too

1st visit: they replaced a vacuum line that had to do with the fuel system, no change
2nd visit: they replaced an air temperature sensor
3rd visit: Here's exactly what it says on the paperwork :

Verify noise right valve cover 2100RPM R-R Valve Cover VGT and front camp cap per ssm
inspect for foreign material none found
Inspect lifter and rocker ok
contact hotline told to disconnect vgt to see if noise stops
noise did stop
no repair to be made at this time
engineering is working on the problem


My service writer says "oh that's nothing to worry about"

Car has 35,935 miles on it.

I've been having the same problem. While it's not completely fixed, they did find that one O2 sensor was slow to respond. Replacing it did improve the situation noticeably for me.

I also have a ticking noise (around 1200RPM) which was localized as being the loudest at the #4 intake runner. I bet the mention of SSM refers to the aftermarket oil filter issue of blocking the oil gallery. The dealer(s!) here don't want to open my engine to check the cams.

Sounds to me like you may have an issue with the variable cam phasers. I don't know much about them but do know they are on both the 3 valve 4.6L & 5.4L. Could be that they are looking into what could be causing the sound and will contact you back when they come up with something. In the meantime they feel that the car is safe to drive.

I attached a little info on them from Comp Cams to dive you and idea of what the Phasers do.

VGT = variable geometry turbine

Typo?

The VCT system is known to be flaky and a service liability. I'm just planning on replacing mine when/if they start acting up...