Alright...here's the rest of the story on my CX-7. It has spent the last 30 days in the shop. I'll add that this is shop is fully equipped with ALL the tools necessary for modern vehicles AND experienced techs to do the work...they are top notch.

Anyway, I took it in as it had an oil leak around the timing cover and one on the oil pan...along with the mystery noise/rattle. The techs went through that engine from top to bottom and checked everything. Timing is right on..no problems. VVT is working as it should. All cylinders and the turbo were scoped and look great. HP fuel pump is fine, all injectors are fine. Spark plugs were changed as the previous owner had not replaced them all with the same type...all were different and one was almost burned up. Coils check out. All electrical connections were cleaned as well as making sure the grounds were good. Intake removed and inspected...no problems there. He also updated the ECM with the latest software. Overall, it's in great shape for a 92k mile engine. It runs great, BUT is still a bit noisy on acceleration. The shop owner is baffled by the noise and asked if I had another way to go to work so I could leave it with him. He really wants to find out what's causing that. If I had another way to go, I may have left it with him as I'm equally as curious as to what's causing that noise. He also checked with the Mazda techs at a nearby dealership. Those guys have had cars come in with that same noise and have fixed exactly NONE of them. They have no idea what's causing it. My shop tech did ALOT of research and was not able to find anything about a possible cause. According to the service records I was able to find via CarFax, the original owner was very good about regular maintenance. All recalls were done and nothing was mentioned about the mystery noise.

So, it runs great and everything is working fine. I'm just gonna drive it and let it be. The mystery noise isn't that bad and is not continuous...just sometimes on acceleration. Last night I took the wife out for a ride so she could hear it and from a dead stop, I took off and it didn't make any noise at all...smooth, quiet acceleration up to high speed (65-70 mph). On the way to work this morning, it rattled a little...but not much. I can deal with it and like all my previous vehicles, I'll make sure it's well maintained and I hope to get alot of miles out of it.

Sorry that I couldn't shed any light on the cause of this mystery noise....but wanted to come back and finish the story.

Well, good to hear I suppose. Maybe the noise will just eventually go away like mine did. Thanks for posting.

Thanks! Maybe it will go away on it's own. That would be nice.

Update: After not being able to determine the cause of the rattling/clattering (whatever you want to call it) sound on acceleration...and driving it for a week back and forth to work (about 30 mile round trip), another problem starting popping up. It started throwing codes for misfires on cylinders 3 and 4. Back to the shop we go and after pulling the valve cover, he found that oil was getting into those two cylinders, fouling out the plugs. So, after a discussion with the mechanic, I had two options. Option 1 was just driving it until it destroyed itself. Option 2, replace the engine (and turbo). I picked option 2. Yep, not exactly a cheap option...but with used car prices being as stupid as they are today, still cheaper than buying another car and eating what I've already got in this one...and my wife agrees. Engine (long block) came in yesterday and the turbo will be a few more days. Old engine is already out and when the turbo gets here, he'll start the process.

Well, dang.
I agree with your choice. Used cars are still overpriced. I found myself replacing the entire rear subframe of my other daughter's Toyota Matrix last winter for that very same reason. And I believe the cx-7 is a solid car mechanically. Besides the now-gone rattle, coolant line fix and rear bearing assembly, we've had absolutely no other problems with it in six years of ownership . Got new tires put on last August and an alignment wasn't even necessary...all was still within spec.

Thanks, keeping an older car on the road is definitely cheaper than buying another one. Like you, I believe the CX-7 is a solid vehicle and with this new powerplant, it should be good to go for quite some time. Glad to hear the rattle on yours is still gone and it's running like it should.