Clicking / Ticking Noise From Engine When Stopped
I have a 2011 Z71 Tahoe. I noticed a clicking / ticking noise, almost like something loose vibrating (similar to sticking your finger in one of your kid's handheld cooling fans with plastic blade...only louder) coming from the engine when coming to a stop. The noise seems to happen on and off when letting off the accelerator. Once stopped, it occurs any where from 5-10 seconds intermittently. I noticed this a month ago, and tried to determine what it could be. 2 weeks later while driving it began and I received error messages in the following sequence: "Stabilitrak Off", "Service Stabilitrak", "Reduced Engine Power" followed by the check engine light. I was able to get home, but the ride was rough. I took it to my mechanic the next AM with the check engine light still on, the same noise, but no other error messages. The analyzer revealed 2 error messages. Both were "Lean Fuel". He recommended SeaFoam and suspsected bad fuel or water in the fuel system. 1 bottle of SeaFoam and there have been no other error messages and the sound wasn't there. HOWEVER...last week the noise resurfaced, but no error messages. I added another bottle of SeaFoam when fueling, but the noise is still there. I also noticed hesitation when accelerating from a stop during the noise. Took it in to my mechanic today, and of course, when we test drove it the noise could not be replicated. I drove it for about 30 minutes with no luck. Pulling into my neighborhood, it began again coming to stops. Turned around and took it back to the mechanic...you guessed it. No replication during the test drive. As I pulled in to let him off it did happen for about 1/2 sec, but at a very low decible level. He says he hates to replace something that he can't verify is the problem. So, I proceeded home feeling defeated as it began again 1/2 mile from his shop. When I arrived home, pulled into the garage, placed the vehicle in park...again for about 2 seconds. When I turned off the ignition, it happened again. I did read on various forums about the error messages and saw fuel and air intake valve problems, but the mechanic says those don't seem to be the problem. This is my 4th Tahoe and I have not had any "rabbits running into holes" like this. ANYONE HAVE ANY ADVICE???? Thanks.