[714camaro]

Hey guys, so i have a 2016 Camaro ss with an lt4 blower. I just replaced my front main seal this weekend and added a mms catch can.

I replaced the seal with an lt1 seal and added an arp crank bolt torqued to 240 ft lbs. the catch can is set up to vent from the diverter under the blower and the return tees off into my brake booster. The blower and lid was reseated at 89 in lbs with fresh blower to head bolts.

I’m wondering i routed the pcv correctly. Should the vacuum side of the can be tee off into the brake booster or should it be connected to the oil reservoir on the driver side of the engine?

I accidentally got the wrong bracket for the catch can do it is zip tied until the correct mount comes.

After starting the car up for the first time it has a very rough idle. It surges on start up and then almost sounds a blown boat motor. It surges every 2-3 seconds and has a choppy idle in between.

I double checked all my belts, connectors and pcv connections and can’t seem to find an issue. Does anyone know what could cause this?

Here is also a link to a 15 second video i took of the idle on YouTube:
https://youtube.com/shorts/v_6GqALjlzw?feature=share

Thanks in advance.

[Spaceme1117]

I would think some sort of vacuum leak somewhere.

I'd disconnect the catch can and put the PCV system back to stock and see if you still have the issue.

[714camaro]

Originally Posted by Spaceme1117

I would think some sort of vacuum leak somewhere.

I'd disconnect the catch can and put the PCV system back to stock and see if you still have the issue.

Thanks for the input. I’m hoping it’s just a vacuum leak as well. The only issue is i can’t really take the catch can back off because i would have to unbolt the blower again to remove the diverter and put the stock plug back in. The blower bolts are 1 time use so I’m kind of out of luck on removing the catch can. I did just discover that the top filter was slightly loose on the can but that still didn’t fix it.

[714camaro]

So after checking my tee on the brake booster for a vacuum leak i found that i was still able to pull the tee off by hand so I’m going to go grab some hose clamps to add to my tee to see if that solves the problem.

[714camaro]

Added hose clamps and still haven’t found out what the problem is

[Chrome383Z]

Probably a dumb question but was it running rough before? You replaced the front seal…. I’m assuming it was leaking. Hoping you don’t have a ringland failure.

[KingLT1]

data logs are helpful.

[714camaro]

I will have a data log attached by the end of the day.

[ctrlz]

How exactly does that breather work on that catch can? If it is open all the time to atmosphere, there's your leak.

Wrap some duct tape around the breather and see what happens to idle.

[MightyBobo]

Originally Posted by ctrlz

How exactly does that breather work on that catch can? If it is open all the time to atmosphere, there's your leak.

Wrap some duct tape around the breather and see what happens to idle.

I looked up the product and that is how it's designed.

Possibly a leak in the assembly itself?

Looking at your filter in relation to the can, the distance between it looks nearly double what I see in their install photo, and they emphasize to push the breather ALL the way down...did you make sure to do that?

[714camaro]

Originally Posted by MightyBobo

I looked up the product and that is how it's designed.

Possibly a leak in the assembly itself?

Looking at your filter in relation to the can, the distance between it looks nearly double what I see in their install photo, and they emphasize to push the breather ALL the way down...did you make sure to do that?

Thanks everyone for chiming in. In these photos that top filter actually was not all the way seated down. I came back and made sure it was press fit all the way down this time but still didn’t fix the issue. I’m going to unhook the can and check to make sure all the fittings and O-rings are okay.

[ctrlz]

Originally Posted by MightyBobo

I looked up the product and that is how it's designed.

I am blocked from that manufacturer's site here at work. Is there a check valve in there?
The other question is has anyone else here successfully installed that same can?

I still say if rough idle persists (even after making sure fittings are tight), try a wrap of tape to seal off the breather. Easy enough to pull that off.

[714camaro]

UPDATE: I managed to get The whole can system off without removing the blower. I replugged the pcv port right under the throttle body and removed the T in the brake booster. So technically it’s back to how it was before adding the can. The scariest part is i still have the same issue.

That only leaves the crank seal replacement job that i just did as the last variable. I’m going to take off the blower lid and recheck all the blower to head bolts for 89/in lbs and make sure there isn’t a line being pinched under the blower. Something is definitely off.

[714camaro]

I just finished getting the lid off and there is a whole fresh coat of oil in the blower again. It really built up around the lid seal. That’s just from turning the engine over a few times with the catch can on and once with the can off.
I checked all the blower to head bolts. They all slightly went a little tighter with my torque wrench.

I’ll see what else i can find.