Crackling exhaust noise on start up

Every since I went stage 2, or it may have been when I replaced cylinder 2 due to a broken ringland, I've been getting a crackling noise about 10 sec after I start it on a cold engine. It does it for about 15 seconds or so and stops. I'm not sure if it's the exhaust expanding, or if it's related to the cylinder job. I've got MadDad UEL headers/up pipe combo, a CNT catted DP and a Magnaflow cat-back. It's flashed to a stage 2 Cobb tune. I need a protune which I'm planning on soon. Any input/like situations?

can you make a video of the noise ?

the secondary air pumps runs for 10-15 seconds during cold starts, the engine can sometimes run rough and loud for that period and then smooth out shortly after that...

Originally Posted by bmx045

the secondary air pumps runs for 10-15 seconds during cold starts, the engine can sometimes run rough and loud for that period and then smooth out shortly after that...

I was going to say that. But that's a different noise then what he's describing.

Nice try...

listen grandpa, you're stage 1, things change when you actually have performance parts on. though i suggest he's overly rich

I can try getting a video up in a couple days, working a lot in the next few days. Yeah I'm hoping a tune will straighten it out, if it is a problem.

It does run at 1500 rpms at idle for a min on cold starts but this crackle noise is aside from that and clears up before it settles to a 1000 rpm idle.

I still think youre running super rich. The cobb maps can do that. Are you misfiring at all?

The only other thing I notice and it's been doing it since cylinder 2 was replaced, is I get a pretty faint knock occasionally. It's completely inconsistent and it will be up to 30 sec to a min in between. It's a light vibration and a faint knock after its been idling. It sort of skips. My father listened to it and just thought it was tune up issues.

It comes from the motor though, it's not an exhaust noise.

Okay. Who reassembled the engine and did anyone check valve lash? Over time you lash will be smaller and smaller and if you install new valves, they need to match the rest or else you'll have issues. Tight valves can tick tick and tap tap and thats not an issue but if you log roughness in that cylinder and find counts of misfire, the lash isnt appropriate. So figure you have new valves, perhaps too much fuel is entering and detonating due to improper intake and exhaust lash. This could relate to your popping sounds.

My father did the work, he owns a shop. The head was sent to a machine shop to be tested and cleaned, they said everything looked good. We only replaced cylinder 2.

I'll ask him about the valves but I'm pretty sure they weren't replaced, I wasn't there for all of it. He also did the timing belt btw.

The valve lash should be matched to the rest of the cylinders or atleast within subaru spec.

He told me the machine shop told him Everything was within spec but I don't know the extent of what they had