OEM Plenum issue

Hello guys

I’m facing a problem after reinstalling the plenum back
Now while cruising on highway the throttle seems like shutting or misfire which hold the car from moving and this happen only on partial throttle between 2000-3000 RPM. Mid to heavy throttle have no issue.

We took off the plenum and installed it again to make sure everything in place but the issue still there.

While reving the car on idle till 3000 rpm and of course partial throttle only
There is a sound coming from plenum side.

https://www.m3post.com/forums/showthread.php?t=1907329 Exactly the same issue described here but unfortunatley he didn’t mention if he fixed it or not.

Could it be failed pcv?

Here is a video the sound coming

No codes found.

Hopefully someone can help

Thanks

Edit: Problem fixed after taking out the RTV Silicone that i applied to fix plenum whistle.

I would double check that the rear of the plenum is seated completely, if not it might rub and vibrate against the strut brace. I’ve had that issue in the past. Secondly, make sure the rear hose is clicked in, it can be a pain in the ass. Beyond that I’m no help. Good luck! (I assume you didn’t do anything else beside remove the plenum based on your post, correct?)

nick3753 wrote

I would double check that the rear of the plenum is seated completely, if not it might rub and vibrate against the strut brace. I’ve had that issue in the past. Secondly, make sure the rear hose is clicked in, it can be a pain in the ass. Beyond that I’m no help. Good luck! (I assume you didn’t do anything else beside remove the plenum based on your post, correct?)

I just removed the plenum and put it back and make sure it’s fully seated from rear and front.

All connections secured but still the sound is coming and the hesitation on partial throttle still there.

And yes no other work done beside plenum removal.

Really appreciate your input

Check out this thread here, you might be experiencing the same issue.

Theodore2 wrote

Check out this thread here, you might be experiencing the same issue.

I already had this and fixed.

This is somethig else as it misfires and sound different.

But thank you for you input

Can you post photos of all the connection points under the plenum? No need to remove the plenum, just turn the light on for your phone and snap photos of the space between the plenum and the the engine all the way around the plenum, just in case something is out of place or broken and you just missed it accidentally.

Theodore2 wrote

Can you post photos of all the connection points under the plenum? No need to remove the plenum, just turn the light on for your phone and snap photos of the space between the plenum and the the engine all the way around the plenum, just in case something is out of place or broken and you just missed it accidentally.

I took the car to a garage and they suspect it’s the oil seprators as they say this sounds like a pcv, could be it damaged while removing the plenum ? And does that make misfire on partial throttle ?

Replied to your PM. Remove the plenum and drive without it. Car will drive just fine in alpha-n mode. If the issue is gone then it's something with the plenum. It sounds like a vacuum leak to me.

Redd wrote

Replied to your PM. Remove the plenum and drive without it. Car will drive just fine in alpha-n mode. If the issue is gone then it's something with the plenum. It sounds like a vacuum leak to me.

I started the car with the plenum off and the sound goes away.

But the hesitation still there specially on 3000 rpm.

Will a smoke test verify if there is a leak in the plenum itself ?

Thanks

Did you ever resolved this issue?

Robocop305 wrote

Did you ever resolved this issue?

Yes problem fixed
It was the RTV that i applied to fix plenum whistle issue, once i took that out everthing back to normal.

Moutamid wrote

Yes problem fixed
It was the RTV that i applied to fix plenum whistle issue, once i took that out everthing back to normal.

But the whistle sound is still there ?