M42 buzz

[bo-vice]

right, ive got a 91 318is, runs great drives great, love the car but the sound this car makes is horrid.

when i bought it, it had some aftermarket cheap cheap garbage on it. stock cat and resonator gone , replaced with who knows what, rear muffler replaces with massive pop can. right away i replaced rusty garbage cat with a magnaflow high flow cat, and replaced muffler with magnaflow muffler. Mostly the reason for putting magnaflow on was cause it was cheap and i needed to pass aircare right away, and i did with flying colors.

the sound out the back is decent, not too loud, but not as much of a low deeper sound that i want. the real crap sound seems to be coming from under the car near the front.... its like a buzzing metal kind of sound when i really stomp the gas mixed with a low but strong HISSSSss. its to the point where its embarrasing when mashing the gas and just trying to have a bit of fun.

I got it checked out today at a local shop to check for leaks, the only leak they found was right before the crack , but they welded it up and the sound is still there.... is this a common sound for an M42?? he told me they are usually a pretty buzzy engine..but had a face like "but usually not this bad"

please help as its driving me nuts. :drink:

[tonywonder]

record and post audio. maybe its turbod

[Ian Bowers]

Does the car have a stock airbox on it? The low hiss sounds like it might just be intake noise.

[Dj Buttchug]

check your heat shields under the car. you might have some contact/ loose panels and it buzzes at higher engine speed.

[tonywonder]

ive had a loose 02 sensor that made an annoying rattle sound. but im with assdrink on this one. sounds super gheetttooo.

[Ryann]

I've got a 100% stock m42 from the airbox to the muffler. Everything's low miles and in good order. No intake leaks, no exhaust leaks, and the timing set is proper w/o rattle. That having been said, it is a relatively loud car! With the hood open a pronounced ringing and hissing resonates from the throttle body and cam cover area. The exhaust at idle is throaty and aggressive, to the point that my neighbor has commented on it. There's lots of raspy obnoxiousness when you take it into the upper registers. My kids often times hear me coming from down the street and are standing on the front porch to greet me as I pull into the driveway. Not sure if this helps, but it's a benchmark for you.

[Dj Buttchug]

ive had a loose 02 sensor that made an annoying rattle sound. but im with assdrink on this one. sounds super gheetttooo.

lol

[///digitalme]

i have a hizz on my engine but thats because of the timing overhaul mines sounds more of a supercharger though....but intake makes a buzzing sound i have a kamotors intake and its hella loud so i took it off


video of it would be nice

[bo-vice]

Not the airbox and not the o2 sensor.possibly some super heatshield vibrations but seems a tad different..

When you guys drive with your window down and plant your foot do you hear the sound of your rear muffler? Cause i mostly hear noise from under car/ front end. Metallic vaccum steeZ. Almost as if headers/ cat is made of tinfoil.

Ill try to get some sound clips tomorow..could be tricky tho as i can imagine it all just being wind noise being recorded.

Guy at shop said to try just buying all stock components and starting over, then went on to say he could get me a brand new one from bmw.... Probly just a steal of a deal.

[Eecen]

M42s are noisy little fuckers...especially at 3k+. Lots of noise with little action (in a straight line)

But as others said you might have a loose something vibrating against somethign else.



Should also keep in mind that your car sounds different from the inside than outside.

[grippymonkey]

oh man another M42 noise thread

it's pretty hard for people over the internet to diagnose your problem (if there is one)

as said these cars are typically noisy... it could be a list of things... most of which are nothing you can fix

[rjcaptsean]

My car was set up similarly. PO had replaced the stock cat and resonator with two used cats from something else. Muffler was completely shot inside and rattling bad. Replaced the muffler with a magnaflow, it sounded better, but there was a definite loud buzz when you stepped on it. Very embarrassing. Since the two cat combo didn't fly real well with the AirQuality folks here, I found a new cat (Magnaflow also AND a new resonator). It's not in yet, but I'm hoping that crazy buzz sound is gone after I have it installed.

[bo-vice]

Keep me posted aayyee?

[spud814]

I have had the same problem the last 5 years. Anyone fix this?

[immajackuup]

my stock intake hissss above 3k because I've taken this piece out.