8-4-1 Headers (Video)

[JTM88]

I had a similar sound after installing long-tube headers, although the circumstances were a little different. Whenever I made a left turn at speed through an intersection, the engine would tilt just enough for the passenger-side header to contact the A/C line.

Since yours happens on right turns, it makes me wonder if the header is contacting the steering shaft instead.

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[WItoTX]

OP, how do your motor mounts look? Might be a good time to replace those as well if the motor is moving and the headers are out.

 

[TreeFiddyAre]

Will be interesting what they find wrong.
My fake money bet is on the steering shaft to header tube interference especially knowing the steering shaft has to be disconnected for header install.

She is going to the shop in the am...I might just be that but what is odd is how intermittent has become but it is always in the same spot and the faster I go the faster the vibration is...I hope its just interference and not an electrical component

 

[GregO]

the faster I go the faster the vibration is...

As speed increases so does engine RPM’s and with that comes higher vibration frequencies.

I’ll raise my fake money bet double or nothing it’s steering shaft to header clearance and possibly a slight motor shift to one side for added clearance. 304 SS grows a lot when hot.

 

[TreeFiddyAre]

As speed increases so does engine RPM’s and with that comes higher vibration frequencies.

I’ll raise my fake money bet double or nothing it’s steering shaft to header clearance and possibly a slight motor shift to one side for added clearance. 304 SS grows a lot when hot.

The more I drive it, the more I'm convinced this has something to do with the EPAS.

Here's where it gets interesting...

If I set the steering to Comfort, the vibration/buzz is much slower and less aggressive. Switch it over to Sport, and the frequency increases noticeably. It also scales with vehicle speed. If I quickly turn the wheel at 10 mph, the vibration is there, but at 30 mph it's much more aggressive. The fault only exists within a tiny window of steering wheel rotation (about the 2:45–3:00 position), and once you rotate past that point it disappears immediately. The other direction is very intermittent and when it goes off its right off 12 o'clock .

The best way I can describe it is that it feels like the steering rack or EPAS motor is having an identity crisis trying to figure out how much "fake weight" it wants to add to the steering. It's almost like the assist motor starts oscillating because it's confused about what it should be doing in that exact steering position.

So, long story short:

- Headers aren't touching anything.
-Plenty of clearance to the steering shaft.
-No witness marks anywhere.
-The issue is both speed-dependent and drive-mode dependent, which makes me think it's electronic rather than mechanical. It sounds and feels far tooo much like an electrical motor trying to create a sensation at the wrong time

She heads to the stealership Tuesday at 10:00 AM.

Let's see if my extended warranty and the service advisor can peacefully coexist with a set of long tubes... Wish me luck

 

[GregO]

@TreeFiddyAre
Good thing that was a fake double or nothing bet…. Well, best of luck to you.

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