2007 Tacoma 2.7 Timing Chain Replacement

For the last 6 months or so, I couldn't figure out why my 2.7 was valve pinging in 3rd or 4th gear at low RPMs. Truck has 242,000 miles on it. Checked everything that could be checked. And, no engine codes. Last resort was the timing chain, and that seems to have been the problem. With the tensioners all the way out and the chain loose and stretched, the engine wasn't able to advance or retard timing as needed when accelerating. So I had a mechanic friend replace my timing chains, tensioners, and guides. Running great now, no more pinging. It's a big job.

 

I see what looks to be another smaller chain at the bottom behind the main timing chain. If so, what does that do and was it also replaced, and if not, why not ? Thanks in advance.

 

Yes, that one was replaced as well. There are two models of 2.7. This is the 2TR-FE. Pretty sure that the bottom chain dampens vibrations that might come from the crank shaft. It also has a tensioner at the top.