In the last week my 02 MCS has developed an unusual sound. it sounds like popcorn popping, but a bit less pronounced and more metallic.

Initially I thought for sure it was pinging (it's similar sounding), but I don't think the conditions are right for that. It only seems to happen when the car is cold, and it goes away once the car reaches operating temperature. It's most predominant under light acceleration, heavy load or WOT makes it stop. I can't get it to do it when the car is sitting still in neutral, only happens when the car is actually moving.

It's a pretty significant sound, can be heard inside the cabin or outside with the windows down. I don't detect any power loss, otherwise the car seems to run as always.

Mods are: 15% pulley, Altai CAI, DTBPV, Brisk DR12s, Alta Unichip. I tried switching maps on the Unichip and removing it altogether, made no difference. I checked the plugs, they look fine. Have only been in the car for a month.

Car only gets 93 octane from Shell or BP, 94 when I can make my way to a Sunoco station.

Any ideas?

 

does it sound like playing cards in spokes? and happen between 3-4 thousand rpms? and more pronounced if you open the passenger window? if yes to the above think about changing the harmonic damper to an 05 - 06 .

 

No, although I do have the playing card in the spokes sound, which was going to be another post soon. However, I'm not convinced it's the harmonic damper. This sound goes in harmony with the speed of the car, not necessarily engine RPM. When I brake it gets louder and more pronounced. I have M7 slotted/drilled rotor, my guess is I have a dragging brake pad that is making the sound as it passes over the slots in the rotor, that's what it sounds like to me (it's what that would sound like in my head anyway), but I could be way off base. That particular sound started about a week after the pads/rotors were installed and has gotten progressively more pronounced with time.

 

Update to this if anyone is looking and can lend a hand. The sound seemed to start to get worse, and a bit less random. I've been able to determine it comes on right around 2000 rpm and seems to stop by 3200 or so. It went from the "popcorn" sound I described before to more of a steady popping or clicking sound through the mentioned RPMs. I can get it to do it a little below or above those RPMs but it's most predominant there.

I dug out my code reader and pulled one stored code, P0341, for the Cam Position Sensor. I had no SES light. I cleared the code, and for the first 10 or so miles everything was the same, but then I swear it started to diminish and I then drove about 40 miles without it returning.

So now, while I'm happy it's gone (for now), I'm concerned there may be something else at play. And I don't understand how clearing a code could actually solve a problem like this. Any thoughts? Timing chain maybe?

 

I don't know but it sounds very similar to the sound I am experiencing and I posted in this thread https://www.northamericanmotoring.co...ng-3k-rpm.html

It's subtle but unoticeable to the untrained ear, unless you point it out. I don't think it has any effect on performance, it does sound like something is loose or just slightly off. I'm not too worried about it but I will mention it to my MA next time I'm due in for service.

 

Thanks for the link. The way you describe you sound makes it sound more like a bad harmonic damper, the playing card sound seems to go along with that from what I've read.

after doing some more research, I'm beginning to wonder if it' not my belt tensioner. I dug up quite a few posts that saw that a bad tensioner can sound like pinging, and I did just install a new belt a couple weeks ago so possibly that may have lead to this problem... I have about 2/3 of a hole showing so it seems to still be working fine, but maybe something else is afoot with it... Sounds like a trip to the dealer next week. )-: