2008 CX7 sudden engine rattle/knock and loss of power. Help
 

Hi guys/gals just after some help/knowledge if possible please.
my wife has a 08 CX7 and it has recently found a loud rattle/knocking in the engine which is causing power loss and struggling to rev.
Im thinking its the timing chain but not 100% as Ive read similar characteristics turning out to be a simple pulley bearing, but I can't see how this could cause power loss?
I tried to upload a video of the car running but it wouldn't work for some reason.
any help on how to diagnose or what to check would be greatly appreciated

Has it been scanned for trouble codes?

No it hasn't mate,
will it spit out a code if there is no engine light or warning on the dash?
what is the best scanner to use on the Mazdas?

Highly likely there will be codes, not all codes will illuminate the warning light.

Best scan tool is Mazda's own MMDS.

Had the car scanned today with a snap on scanner
and no codes besides an ac temp control error code
which may explain the poor a/c quality
Also mechanic checked the timing chain through the oil cap and said he had no slack so its not that,
also removed the serpentine belt and ran the engine to eliminate any possible pulley problems,
he was leaning towards a shot turbo, but to me the rattle/knock sounds internal.
but will check the Turbs to see

Harro

Please keep us posted on your progress. I am buying a CX7 today and it has the same problem. I plan on repairing and flipping for a profit. It has an incredibly loud knocking. The current owner said that they had the turbo replaced then the knock developed 5 months later. I'm thinking the turbo is to blame,