Just got Motordyne 5/16 Plenum Spacer installed from Performance Nissan.
I've been driving it for about one hour and I noticed that
there's strange vibration/rumble from underneath the car when accelerating
in low RPMs in 1st and 2nd gear.

Is this normal?

I thought it felt like it was my Y-pipe sending all the air fuel to my exhaust or something.
Any input would be appreciated.

 

ttt

 

hmmmm...interesting.. this only happens in 1 and 2 ? nothing at idle.. or in other gears?

 

What's that supposed to mean -_-?

 

Yup, nothing at idle, only on 1st and 2nd gear below like 2500rpm, goes away
as the rpm rises...
I called Perf Nissan and talked to one of the Nismo guys, and he told me
it takes a bit to settle in? e.g. for ecu to get used to it and stuff...
Well I'll test drive it some more tonite.

 

^^
Interesting note, I thought I read a post about a guy that was unhappy about an exhaust installation there. Give us an update later.

 

It sounds to me like the strut bar may need to be adjusted a little more.
Go to the last page of the installation instructions and it will show you what to do.

Let me know what you find.
Tony

 

yup, i bet its your strut bar touching your plenum when the engine moves.

 

heh, they beat me to it... yeah, check that strut bar out and like Tony mentioned, check the install instructions on how to set 'er straight. Let us know what you find out.

 

I believe ttt means "to the top"...correct me if im wrong, someone

 

Correct thats what it means. I think it is rubing the strut bar as well.

 

Check your strut bar like stated above. I ran into that same problem.

 

One easy to way to tell for sure if it's the strut bar is to just remove it and see if the problem goes away. If it does then you know you what the problem is. Just keep in mind that adjusting the strut bar perfectly can be a PITA! If you raise it too high the hood will "bulge" and if it's too low it will cause the vibration problem you are having. I have spent hours trying to get mine just right but the hood still bulges slightly. It's a minor problem but it is noticeable when you look at the hood from the side. You can tell the hood is slightly higher than the quarter panels. I am going to attempt to fix it in the spring. Right now the car is hibernating for the winter.

 

I've looked if the strut bar has enough clearence, and it looks like
the bar itself isn't touching the engine.
However, the clearance space is pretty damn tight, like less than 1/4th of an inch.
This could be touching the engine when the engine starts to vibrate.
I'll take off the strut bar when I get off work and see if the problem still persists or not.

 

while you're at it, you might as well check the tension on the plenum bolts. they can come loose over time.

 

When you take the strut bar off there will be signs if the strut bar is rubbing the plenum. You will see scratches or wear marks on either the plenum or strut bar if they are contacting each other.
Just because there is clearance when your looking at it that doesn't mean there is enough clearance when the motor is under load. That's why the exhaust has flex pipes and hangs on rubber hangers. That way it can give slightly as the motor moves.

 

Hey Beeker you're exactly right. I found scratch on the strut bar and
rubbing mark on the engine.
My strut bar is off for now. I'm thinking about getting aftermarket strut bar
that's better and also will clear even the 1/2" spacer.
Oh btw, where can I get instructions on adjusting stock strut bar? Tony
may be able to help?

 

A strutbar adjustment procedure is on the last page of the Motordyne installation manual. Download it from our site and let me know if you have any questions.

Tony

 

there aren't any aftermarket strut bars out there that are better than stock IMO(in my opinion), i'd try adjusting it first... it should have been checked and adjusted after the install since this problem is pretty common