I have an 06 touring 5at. Mods that would come into question - z1 upper intake plenum and 5/16 spacer. Lower collector is p&p. I adjusted the strut bar to keep it from rubbing against the plenum.
I've noticed the problem when accelerating from a stop. Seems to only happen in 1 st gear when accelerating normally or slowly. But once I get to about 2k it makes a kind of grinding sound. At first I was thinking it was because I was about 1k over my oil change so I changed the oil that day. New oil filter 5 quarts of oil. My gf's mom brought it home from work (she works at a parts store) I noticed she didn't get like amsoil or anything like that. Could that be the problem? Cause it still makes the grinding sound every once in awhile roughly 3/10 times I stop and go to accelerate. But if it was the type of oil then why'd it make the sound before the oil change?

Anyone have any idea why its making the sound? Also when accelerating it will continue to make the grinding/groaning like sound until it goes into 2nd gear and the sound slowly dissipates. Whether I let it shift around 3k or 6k it still makes the sound all the way through

 

Sounds like you could be describing the normal transmission chatter (aka cement truck rattle) of our lovely CD00x transmissions. All Z make this noise to varying degrees and is normal. The sound was audible when I purchased the car stock, became even louder once I installed a single mass flywheel.

Go somewhere quiet or at night and put it in neutral, get out and stick your head under the car right about where the driver sits and listen...you should hear the characteristic chatter/grinding sound faintly coming from the trans...you should recognize whether it sounds the same as what your hearing or if it sounds completely different.

 

Also, if it is transmission chatter, the sound should go away completely when the clutch is depressed, and come back after you release the clutch in any gear even in neutral.

 

You missed this part...

 

^LMAO! Everything I said, ignore it!!!!!

 

It's definitely coming from the front?

 

Could be a pulley going out. If something internal in your engine is grinding you could run unicorn tears through it and it wouldn't solve it.

 

I suppose it could be the crank pulley. But its kinda similar to the sound of the strut bar touching but it only happens at a certain point while in gear between 2 and 4k rpms then the sound usually goes away but seems like it doesn't give as much power as normal. Some of my research pointed at the motor mount but it really sounds like the internals almost like maybe a piston is rubbing the cylinder or something. Cause as it revs higher the sound becomes louder as if its vibrating against something I guess it could be the strut bar but it still has plenty of clearance. Anything you guys can think of that could give off that same sound?

 

Yeah its definitely coming from the engine bay area. I thought it was the strut bar because it made the same sound when I installed the spacer and didn't adjust it and the bar was touching but its not touching now and hasn't for at least a month. As I mentioned I thought it was maybe the oil but its still doing it after the oil change and has been about a week now. It doesn't seem to do it as often but is say 1/5 times accelerating from a stop it does it

 

UPDATE: I have not heard the noise at all lately while driving. I'm thinking it was just the oil needing changing, and it just took a bit to get all lubed up and such again. I cannot say that its exactly the problem but it seems likely. It really killed me to not change the oil for that long but I didn't have much other choice and I only took it right around 5k since the last oil change. But I know I won't take it more than 3k again, I'd rather park it til I could change it.

On a seperate note however I drove the car super easy for a week staying under 3k rpms and was able to squeeze just over 21 mpg!! Vs my average of 16-17