Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Seth Hamilton
 
Join Date: Jan 2011
Location: Orange County, CA
Posts: 92
930 Exhaust sounds like a fart - Help

Hello,
I have a 35k mile 79 930 with an Andial rebuild on the motor done a few thousand miles ago to stock specs. The car made some really terrible fart noises out of the exhaust when it came on boost so I figured I would toss on a fabspeed supercup. Well, it sounds better at idle, makes some great rumble noises, and still a very loud fart noise that continues as you are on boost, then stops when off boost. Yes, it sounds as I described it - Not a pleasant growl, howl, rumble or scream, just a loud ripper of a fart. I have and have had plenty of 911s and Turbos, so I know how they really should sound but this is the first stock 930 I have owned. Any ideas on how to mitigate this a bit? Headers, new turbo, something else that I may not even be thinking of?

Thanks,
Seth
__________________
Collector of stuff most don't care about.
Garage- 2018 GT3 (6spd,LWB, Chalk). 69 911t Hot Rod. 964 Turbo. 79 930. 88 M3. 72 280 SEL. F80 M3 (Modded). Boring daily driven things. Other 911s sadly sold.
Old 12-18-2018, 12:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,029
Garage
How is it running? Do you have an afr gauge? Is it on boost onset?
__________________
Turbo powa!
1977 911s. it's cool
Old 12-18-2018, 01:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Seth Hamilton
 
Join Date: Jan 2011
Location: Orange County, CA
Posts: 92
Quote:
Originally Posted by quattrorunner View Post
How is it running? Do you have an afr gauge? Is it on boost onset?
It is running very well. Super healthy, no smoke, smooth power and plenty of it. The noise just throws me off... I can't quite pin it.

No, I don't have an AFR but that could be a good start.
__________________
Collector of stuff most don't care about.
Garage- 2018 GT3 (6spd,LWB, Chalk). 69 911t Hot Rod. 964 Turbo. 79 930. 88 M3. 72 280 SEL. F80 M3 (Modded). Boring daily driven things. Other 911s sadly sold.
Old 12-18-2018, 01:20 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,029
Garage
Do you think it might be a vacuum/boost leak or something? Flutter from a flimsy rubber comes to mind. Other than that I’m stumped.
__________________
Turbo powa!
1977 911s. it's cool
Old 12-18-2018, 02:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Seth Hamilton
 
Join Date: Jan 2011
Location: Orange County, CA
Posts: 92
Quote:
Originally Posted by quattrorunner View Post
Do you think it might be a vacuum/boost leak or something? Flutter from a flimsy rubber comes to mind. Other than that Iím stumped.
I guess anything is possible, but it doesn't sound like a leak of any sort. I will try to get a video soon and post it here.
__________________
Collector of stuff most don't care about.
Garage- 2018 GT3 (6spd,LWB, Chalk). 69 911t Hot Rod. 964 Turbo. 79 930. 88 M3. 72 280 SEL. F80 M3 (Modded). Boring daily driven things. Other 911s sadly sold.
Old 12-18-2018, 02:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Aug 2007
Location: Austin
Posts: 435
Broken head studs can allow the a head to walk/vibrate under boost
and
it sounds bad when it happens
Old 12-18-2018, 03:14 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered User
 
Join Date: May 2015
Location: Secret lair deep underground
Posts: 1,073
Garage
Quote:
Originally Posted by Black_Hat View Post
Broken head studs can allow the a head to walk/vibrate under boost
and
it sounds bad when it happens
I hate to say it, but that's what immediately came to mind for me.

I remember when it happened on my SC (thankfully the turbo is fine, I check the head stud torque every year when I check the valves and do the annual maint).

When I got on it the head/cylinder would separate and made a weird raspy noise. When you hear it, you know it ain't right.
Old 12-18-2018, 05:17 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
scottrx7tt's Avatar
 
Join Date: Feb 2009
Location: Knoxville, TN
Posts: 1,013
Are you sure the wastegate piping has not been modified to vent to the atmosphere rather than through a muffler?
__________________
1979 911SC widebody conversion. 3.1 engine, 3.2 liter heads, carrera intake, Microsquirt V3 ECU, K27 7200 High flow turbo, Tial F41 wastegate, Ford EDIS. .7 bar. 402hp 360tq
Old 12-18-2018, 05:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Non User
 
infraredcalvin's Avatar
 
Join Date: Sep 2007
Location: Ladera Ranch, CA
Posts: 1,293
Garage
Quote:
Originally Posted by scottrx7tt View Post
Are you sure the wastegate piping has not been modified to vent to the atmosphere rather than through a muffler?
Yes, check wastegate routing and possible leaks as well...
__________________
Infraredcalvin - AKA Pat
'76 Turbo Carrera #311 - Factory LSD, Sport Seats
'75 914 GT clone project
'71 914 track car
Old 12-18-2018, 06:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
trunk monkey?
Old 12-18-2018, 08:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 11,600
naaa, not head studs. don't scare the guy yet

could be you have a bad over boost sensor making the "rev limiter" kick in.

you can ground the wire going to the OB sensor and drive it.

check the vac hose to the WUR. make sure it is connected.

start with the easy stuff
__________________
86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:

Last edited by T77911S; 12-19-2018 at 07:07 AM..
Old 12-19-2018, 03:09 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: May 2015
Location: Secret lair deep underground
Posts: 1,073
Garage
Quote:
Originally Posted by JFairman View Post
trunk monkey?
I don't know what one is, but I want one!
Old 12-19-2018, 04:15 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
 
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,722
Garage
Quote:
Broken head studs can allow the a head to walk/vibrate under boost

This was my initial thought as well. Because it only happens under boost it may not have damaged anything yet. When you hear that noise off-boost things are bad. Pull the valve covers and take a look, if this is the problem you want to know about it.

The overboost switch cuts the pumps and gives the dash-in-face response which is unmistakable. Over-rev and you get a machine gun sound.

Also, as a side note, I would never have sold you a muffler to cure an unidentified noise. A conversation would have taken place first to find the problem.



.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8

Last edited by RarlyL8; 12-19-2018 at 06:02 AM..
Old 12-19-2018, 05:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Seth Hamilton
 
Join Date: Jan 2011
Location: Orange County, CA
Posts: 92
Thank you all for the feedback.

Yes, the head issue could be a concern but I sure hope that isn't the case. I could see how the noise of this type could be a result. Crossing my fingers for the best.

The waste gate shouldn't be it as the factory muffler would have muffled it, and now with an open to atmosphere setup it is still there just louder.

T77911S -The boost and revs continue upwards with throttle, so wouldn't that prove to not be the boost sensor?

RarlyL8- I actually had a return to Fabspeed from a 964 cat with gave me credit with them, and that was the reason for going with the supercup. I actually just installed your 2 in 2 out sport muffler on my 69 over the weekend. It sounds great (I had megaphones) and if anything I could have had it even louder. Very pleased with it so far.
__________________
Collector of stuff most don't care about.
Garage- 2018 GT3 (6spd,LWB, Chalk). 69 911t Hot Rod. 964 Turbo. 79 930. 88 M3. 72 280 SEL. F80 M3 (Modded). Boring daily driven things. Other 911s sadly sold.
Old 12-19-2018, 10:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Seth Hamilton
 
Join Date: Jan 2011
Location: Orange County, CA
Posts: 92
I took a quick video of the exhaust list night while driving. Check out the Honda fart sounds

__________________
Collector of stuff most don't care about.
Garage- 2018 GT3 (6spd,LWB, Chalk). 69 911t Hot Rod. 964 Turbo. 79 930. 88 M3. 72 280 SEL. F80 M3 (Modded). Boring daily driven things. Other 911s sadly sold.
Old 12-19-2018, 10:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Brando
 
quattrorunner's Avatar
 
Join Date: May 2006
Location: Las vegas
Posts: 6,029
Garage
You're sure it's not tire rubbing?
__________________
Turbo powa!
1977 911s. it's cool
Old 12-19-2018, 11:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
Join Date: Feb 2010
Location: Finland
Posts: 262
Quote:
Originally Posted by HamiltonSeth View Post
Hello,
The car made some really terrible fart noises out of the exhaust when it came on boost so I figured I would toss on a fabspeed supercup. Well, it sounds better at idle, makes some great rumble noises, and still a very loud fart noise
Thanks,
Seth
Quote:
Originally Posted by HamiltonSeth View Post
I took a quick video of the exhaust list night while driving. Check out the Honda fart sounds
Sure sounds like exhaust drone.

Checked youtube for some Fabspeed exhausts. They seem to have drone too.

Surprisingly many make fartcan -exhausts and youtube is full of comments they sound awesome, which I find funny, but guess that sells.

Think your ears are working good, and it is right to be annoyed at that sound.
__________________
'76 930
Old 12-19-2018, 12:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
Quote:
Originally Posted by flightlead404 View Post
I don't know what one is, but I want one!
https://www.youtube.com/watch?v=Rx6WB5YJia8
Old 12-19-2018, 02:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Registered User
 
Join Date: May 2015
Location: Secret lair deep underground
Posts: 1,073
Garage
Quote:
Originally Posted by HamiltonSeth View Post
I took a quick video of the exhaust list night while driving. Check out the Honda fart sounds

I don't hear anything unusual
Old 12-19-2018, 03:07 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Registered User
 
Join Date: May 2015
Location: Secret lair deep underground
Posts: 1,073
Garage
Quote:
Originally Posted by JFairman View Post
OMG!

THAT.

IS.

AWSOMEEEEEEE!!!!!!

Now I really want one
Old 12-19-2018, 03:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 07:25 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.