bullitt69

After straight piping my secondary cats the exhaust system starts vibrating/resonating a bit at precisely 1000-1200 rpm (even when revving while standing still).

The vibration can be felt through the steering wheel.

I had my car lifted up and the tech inspected the car while I was revving. he said that by removing the secondary cat I took weight off the section which causes resonance in the pipes.

Now I kind of feel sorry for cutting off the secondary cat section.

Did anyone have this problem with this mod? Maybe any ideas?

NotABaller

This definitely isnt normal. Does it only vibrate when revving still? or while driving too?

bullitt69

yes, when driving as well. But only in the mentioned rpm range

mrmotoguzzi00

is it rubbing or close to anything ? most likely your not gonna feel that unless it's touching something....

bullitt69

I had that checked, no rubbing!

NotABaller

So the mechanic cut off the cats, and then welded two straight pipes, and now your steering wheel vibrates at 1k-1.5k on all gears, regardless if stationary or moving.

Were you there when the work was done? Is something touching the metal brace that joins the two undersides?

mrmotoguzzi00

any of the rubber muffler hangers worn out ? cracked ? missing ?

Did the exhaust manifold bolts or downpipe bolts get checked ? those can certainly loosen or break if they are moving pipes around to weld....

bullitt69

yep, I was there. Actually the exhaust was touching the steel bar but I had that redone. Now they are no rubbing issues, only this freakin vibration

bullitt69

the rubber components were checked and they seem ok. The manifold bolts were not inspected today, but I was told that the exhaust vibrates after the primary cats which makes me think that the exhaust section closer to the manifold is secure.

Mort

Sounds to me like your pipes are hitting the cross support when the car is running. Maybe not when it is off and you look at it on the hoist. Did they put a good bend in the pipes just before they bolt up to the resonator? If not that is your problem. No on else reports vibration issues especially ones you can feel through the steering wheel. That is the only problem I have heard of so far.

PJmak

Does the engine shake? Look under your hood


Might be something causing the engine to run rough after the mod??

roadkillrob

I have Mikes power pipe in no secondary cat and smooth as butter no vibration, sounds like it is touching something - maybe the pipes he put in were a bit short or long and moved the rest of the exhaust around and it is hitting somewhere else, closer to the motor or the back. Steering wheel vibration would indicate something is touching a steering component or something a steering component is attached to.

Mikegpr03

Call me OCD but I check all against the jig we had fabbed up so the angles and flow is improved yet nothing touches.

bullitt69

I noticed that all your pipes are somehow interconnected. There is either the H pipe or a supporting bar. Mine aren't. Can this be the reason for the increased resonance?

Savage-wp

It must be touching somewhere. Does it do it when the engine is cold? Or only when hot. The exhaust gets longer as it gets hotter. So it may not be touching anywhere when it's cold.

Mikegpr03

Yes it plays a role lots of obsessing over small details and pissing off the fabricator until it was perfect in
every way.

bullitt69

I had the car checked again yesterday - the vibration is coming from the engine, that is why the exhaust is vibrating.

I'm getting no CELs, the vibration occurs only in the 1000-1300 rpm range in all condions (cold/hot engine, stationary/moving/on the lift). The vibration isn't massive, more like a drone which can be heard, felt both in the steering wheel and pedals.

I'm scheduled for an oil service (sevice A) to an MB dealer in 2 weeks. I'll make them look deeper into the problem. All previous inspections were made at a regular auto service shop.

Maybe something is wrong with one of the injectors or harmonic balancer.

Any advice regarding engine vibration issues withou CELs in the low rpm range is very welcome.

bullitt69

Another issue I'm having is humming/droning sound on over-runs. I can't figure out whether it's coming from the engine/tranny area or from the exhaust as a result of the deleted secondary cats

roadkillrob

does it do it in neutral or only in gear, could be a driveline vibration it it only occurs in gear.

bullitt69

The vibration occurs both in neutral and in gear. It seems to be only RPM dependant

BLKROKT

Motor mounts

bullitt69

Both engine mounts and the tranny mount were replaced 2 months ago

PJmak

02 sensors

bullitt69

They were unplugged two times: once when I had the motor mounts replaced, and the second time when I had the secondaries deleted. You think they could have been mismatched? I believe it would have caused I cell due to incorrect values.

PJmak

My car had an odd vibration in drive inidle.

I had a new maf, trans mount, and engine mounts are still solid.

The car would have a very slight vibration, kind of irregular tempo.

Replaced two 02 sensors that I could get to and its gone but its still there while in park. Kind of odd and not 100% sure thats your issue but its worth looking into.

All 02 sensors are different part numbers on my car(98 c43 amg), its probably the same with yours