Exhaust problem and eco stop starts working - Mercedes Benz SLK Forum

AMGs For those high performance Mercedes-Benz R170-SLK 32/R171-SLK 55/R172-SLK 55 cars tuned by AMG -

 1Likes
  • 1 Post By thompstl1
 
LinkBack Thread Tools
#1 Old 08-18-2013
Premium Member
 
randombloke's Avatar
 
Join Date: Mar 2013
Location: West Wales, UK
Vehicle: Gone: 2013 SLK 55 AMG
Posts: 771
Country:
Chats: 0
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Thanks: 72
Thanked 117 Times in 77 Posts
Garage
(Thread Starter)
Exhaust problem and eco stop starts working

Just over a week ago I was out with my wife, giving the car a good run over some nice, fast, twisty welsh roads. I'd been behind a pretty obnoxious X5 driver who was coming to a virtual stop every time anything remotely resembling a bend presented itself, then pushing their foot through the floorpan as soon as they exited it. We'd just gone through a 30mph zone, at the end of which reverts back to 60mph on a straight. So I changed down to 2nd as we crossed the change and planted my right foot.

The noise was horrible: really metallic, raspy - just plain wrong.

The exhaust continued to sound very raspy all the way home. I'd liken it to the exhaust on an e46 m3 - like someone has filled the exhaust with ball bearings. The blip on downshift sounded like a buzz-saw.

Took it out the next day, the exhaust still sounded raspy, and the normal bass that kicks in over 2k rpm was obvious by its absence. Over 4k rpm it just didn't feel like it was picking up as it should and changing gear via the paddles in the higher rpm felt off.

My first though was it was a flaps issue, which would account for the change in noise and the loss of pull at higher rpms if the flow was restricted.

The car got trailered over to the dealer (I live 2 hours/100 miles away) - and then I had the dreaded phone call: they can't find any problem with it, it sounds fine to them. I kept explaining the problem, but they just couldn't see any issues. They even got someone else's 55 in to compare against and said they sounded the same.

Interestingly, one thing they did do was "enrich" the engine via STAR. They said they could do this and still be within MB tolerances.

They trailered it back to me and I took it out for a 12 mile drive - only to instantly know it still didn't sound right. I'd liken it to listening to the exhaust through a pair of cheap speakers - the bass was well down and the treble up on how it should sound. My wife was in the car and said it sounded "nice", but I could tell she wasn't convinced that I was right about the sound not being as it should.

Here's where it got weird though - on the return journey I fired the car up and it was instantly apparent the sound was back as it should be. My wife had an "oh yeah" moment as it was very obvious that there was a ton more bass again, the higher frequencies had lessened, and the 2k flap opening point was back to being obvious again. The car pulls as it should from 4k again too.

Been out in it again today and it's still sounding really nice - I think the enrichment has actually improved the bass slightly too. So all good there if it stays like this.

Weirdly today though, for the umpteenth time since having the car I drove it down our driveway and stopped at the gate. And the engine cut out. Given the car has stop/start, this shouldn't have come as a massive surprise - except I've driven 2,600 miles in the thing and not once has the stop/start ever shown as anything other than inactive when I've been in eco mode. Nothing unusual at all about today - lid was down as normal, car driven from cold - all of about 100 feet. start/stop was showing as "active" on the return journey too.

All very odd.

I really didn't like the feeling of not being able to prove that the car didn't sound right - so I've ordered a Zoom H1 sound recorder in the hope I can capture the sound when it is working as it should, so I can use that as a reference. None of the cameras I have around me capture the sound well enough for that purpose.

Gone: SLK 55 AMG (2013) Iridium Silver / Bengal Red / Black Ash
randombloke is offline  
Sponsored Links
Advertisement
 
#2 Old 08-18-2013
Long Time Member

 
frogfoot's Avatar
 
Join Date: Sep 2009
Vehicle: 2005 slk
Posts: 3,580
Country:
Chats: 1
Mentioned: 157 Post(s)
Tagged: 1 Thread(s)
Quoted: 332 Post(s)
Thanks: 1,759
Thanked 912 Times in 454 Posts
Garage
get a few more miles under its belt mate, I know I have a 350 but the note of the exhaust on mine changed with miles on the clock. maybe you are going through that phase.

if not hammer the dealers


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Designo 6speedMT 350........My weekend , Holiday Transport since 2008
frogfoot is offline  
#3 Old 08-18-2013
Premium Member
 
randombloke's Avatar
 
Join Date: Mar 2013
Location: West Wales, UK
Vehicle: Gone: 2013 SLK 55 AMG
Posts: 771
Country:
Chats: 0
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Thanks: 72
Thanked 117 Times in 77 Posts
Garage
(Thread Starter)
Appreciate the reply, but this wasn't the exhaust bedding in - it was a very definite problem somewhere. You'd have been in no doubt if you'd have heard that initial problem.

It's just so hard to convey stuff like this without being able to provide comparison sounds - hence my trying to get a decent facsimile of the "proper" exhaust note so I can point to that if this happens again.

Gone: SLK 55 AMG (2013) Iridium Silver / Bengal Red / Black Ash
randombloke is offline  
 
#4 Old 08-18-2013
Registered Users
 
Join Date: May 2013
Location: Connecticut
Vehicle: 06 SLK55 Caspian Blue
Other Toys: 07 R500 4Matic Alabaster White, 08 Infiniti G35x
Posts: 390
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Thanks: 1
Thanked 25 Times in 24 Posts
How do the exhaust flaps operate, electric or vacuum? Did the dealer check the operation of the flaps? Loose wire or vacuum line? Any way to set the flaps to open full time even if just temporarily to see if that's the problem?
CT_SLK is offline  
#5 Old 08-18-2013
Premium Member
 
randombloke's Avatar
 
Join Date: Mar 2013
Location: West Wales, UK
Vehicle: Gone: 2013 SLK 55 AMG
Posts: 771
Country:
Chats: 0
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Thanks: 72
Thanked 117 Times in 77 Posts
Garage
(Thread Starter)
the flaps are electronic and variable in the slk -15/30/50 degrees and fully open at WOT. apparently there is no way to check their operation via STAR.

the exhaust is back operating as it should at the moment - my concern is if I get a repeat of the problem.


Sent from AutoGuide.com App

Gone: SLK 55 AMG (2013) Iridium Silver / Bengal Red / Black Ash
randombloke is offline  
#6 Old 08-18-2013
Registered Users
 
thompstl1's Avatar
 
Join Date: May 2013
Location: Orange, Texas
Vehicle: 2013, White/Black, SLK-55 AMG
Other Toys: Corvette Z-06, Jeep SRT-8
Posts: 64
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 14
Thanked 26 Times in 7 Posts
Garage
When our cars were both new, I remember you saying your engine didn't shut off in eco mode like mine did. Sounds like they are the same now! My engine stops too just after I leave the house at the stop sign a few hundred yards from the house.

I'm wondering if you had a cat/converter plugging up? Maybe if failed to become active and was plugging up...... Just a thought anyway... I hate intermittent problems!
thompstl1 is offline  
#7 Old 08-19-2013
Registered Users
 
Join Date: Jun 2013
Location: SF Bay Area
Vehicle: 2011 BMW M3 'Vert
Posts: 31
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 3
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by randombloke View Post
the exhaust is back operating as it should at the moment - my concern is if I get a repeat of the problem.
Definitely sounds like some type of issue ... sorry to hear ... the 55 should NOT sound like an e46 : )

As you know I picked up my e93 after having a new intake and exhaust put on and I had the same experience as you ... of course it sounded different but the acceleration was definitely down. Its back now ... hopefully 'bed in', but thats never a fun feeling.

Here's to hoping it's gone for good!

On a side note, I do have to say that a lot of these issues and the way MB has treated Coop have convinced me to hesitate on the SLK. I was ready to pull the trigger but i'm going to wait a season and see if some of these issues shake out ...
grussgott is offline  
#8 Old 08-19-2013
Premium Member
 
randombloke's Avatar
 
Join Date: Mar 2013
Location: West Wales, UK
Vehicle: Gone: 2013 SLK 55 AMG
Posts: 771
Country:
Chats: 0
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Thanks: 72
Thanked 117 Times in 77 Posts
Garage
(Thread Starter)
Quote:
Originally Posted by thompstl1 View Post
When our cars were both new, I remember you saying your engine didn't shut off in eco mode like mine did. Sounds like they are the same now! My engine stops too just after I leave the house at the stop sign a few hundred yards from the house.

I'm wondering if you had a cat/converter plugging up? Maybe if failed to become active and was plugging up...... Just a thought anyway... I hate intermittent problems!
I really don't like the stop/start - but don't mind having the cylinder deactivation as an option. It's a real shame can't just select the cylinder deactivation on its own.

I don't think I'll ever know for sure what caused the problem I had, I just hope it doesn't come back for round 2. Some kind of blockage does make sense - I initially thought flaps after reading davidkn's thread on his problem - but it could have been a blockage farther back in the system.

Gone: SLK 55 AMG (2013) Iridium Silver / Bengal Red / Black Ash
randombloke is offline  
#9 Old 08-19-2013
Registered Users
 
thompstl1's Avatar
 
Join Date: May 2013
Location: Orange, Texas
Vehicle: 2013, White/Black, SLK-55 AMG
Other Toys: Corvette Z-06, Jeep SRT-8
Posts: 64
Country:
Chats: 0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 14
Thanked 26 Times in 7 Posts
Garage
I like cylinder deactivation too, but that start/stop is painful! I wish the two could be activated separately, and I also wish there was a default position that could be selected, rather than have to switch it off on every vehicle start.

I had a new car once and the cat/converter failed to "activate". The round catalyst inside didn't ever reach the high temperature needed to burn off carbon deposits. Eventually the converter became plugged and it sounded just like the sound you described (even though it was a Chevy Trailblazer S/S with the Corvette engine). Low power, a "buzzing" sounding exhaust. No ability to get past 4,000 RPM's. On occasion, I'd just hold it to the floor and sometimes it would blow the restriction loose and run fine. But eventually it became too plugged and that no longer worked.

After a converter change the vehicle ran perfectly. The mechanic at the dealership told me some converter catalyst gets contaminated from fuel, or maybe oil on startup, or for one of many reasons it just never "lights off".

I think he used an infra-red temperature indicator to measure the outside of the converter while the vehicle was running. It was not reaching the normal temperature was how my problem was diagnosed.

Hope this helps,
Take care
randombloke likes this.
thompstl1 is offline  
Sponsored Links
Advertisement
 
Reply

  Lower Navigation
Go Back   Mercedes Benz SLK Forum > General Discussion about Mercedes Benz SLKs > AMGs

Bookmarks

Quick Reply
Message:
Options
Upload your files to MEGAUPLOAD
Upload your images to ImageShack

Register Now



In order to be able to post messages on the Mercedes Benz SLK Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 

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