C-Class (W203) 2001-2007, C160, C180, C200, C220, C230, C240, C270, C280, C300, C320, C230K, C350, Coupe

Need help - car in shop - weird hard brake/idle problem

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 11-22-2002, 12:06 AM
  #1  
MBWorld Fanatic!
Thread Starter
 
peet's Avatar
 
Join Date: Jun 2002
Location: Chicagoland, IL
Posts: 1,249
Received 17 Likes on 14 Posts
09 C63
Question Need help - car in shop - weird hard brake/idle problem

Please try this. In a short span, accellerate rapidly (about 2 car lengths) and then come to a quick and complete stop.

Also from stop, accellerate about a car length, turn 90 degrees and stop.

Do not decel, just hard brakes stop. Kind like you'd do if someone cut you off.

When doing this, pay attention to your tach. I am mainly interested in the auto tranny but you manuals try too?

Mine feels like the engine is about to stall, the rpm drops to around 200 and then pops back up to 600.

Stealer sez = normal. I don't buy it.

Car is there right now so speed is of the essence. Thanks folks.

Peet
Old 11-22-2002, 08:59 AM
  #2  
MBWorld Fanatic!
 
mctwin2kman's Avatar
 
Join Date: Aug 2002
Location: York, PA
Posts: 2,753
Likes: 0
Received 0 Likes on 0 Posts
2003 C230K Sport Coupe, 1986 190E 2.3
Most Auto's will do that. Crap my Neon and Saturn both will do that. The tranny is not designed to give up that quickly so it drags the engine speed down since the tranny is still engaged. Try jamming the brakes on a standard tranny and not hitting the clutch fast enough. It will do the same thing.
Old 11-22-2002, 10:11 AM
  #3  
MBWorld Fanatic!
 
MarkL's Avatar
 
Join Date: Nov 2001
Location: Gaithersburg, MD
Posts: 1,230
Likes: 0
Received 0 Likes on 0 Posts
2002 C240 6-spd (ret)
Well, the behavior of Neon's and Saturn's may be dubious, in my opinion :o . I've owned many automatics and quick release of the throttle doesn't seem to cause a problem. Actually, I believe most throttle linkages are designed to "buffer" the release of the throttle for a smoother effect. Especially in our MB's with electronic throttle, haven't you noticed this? Also, I don't see how the braking component would affect this behavior, especially with an automatic -- isn't it only the quick release of the throttle that would affect rpm? A manual is a different story due to the direct connection between the trans and engine.
Old 11-22-2002, 10:31 AM
  #4  
MBWorld Fanatic!
 
mctwin2kman's Avatar
 
Join Date: Aug 2002
Location: York, PA
Posts: 2,753
Likes: 0
Received 0 Likes on 0 Posts
2003 C230K Sport Coupe, 1986 190E 2.3
If you understand how an auto works with the torque converter you would also understand that the tranny does not release instantly. There is a slight delay. I have had this happen in every auto car I have driven if I hammer the brakes. Some do it more than others, it is just the way the tranny releases. I have driven quite a few cars in my lifetime since my family owned a car dealership and I worked there for a number of years in all the departments. Some cars this is more noticeable on, especially four bangers. They generally don't have the momentum to be able to deal with slamming on the brakes after accelerating hard as v-6's and v-8's.
Old 11-22-2002, 01:49 PM
  #5  
MBWorld Fanatic!
 
Jim Banville's Avatar
 
Join Date: May 2002
Location: GA
Posts: 1,823
Likes: 0
Received 1 Like on 1 Post
'06 Lexus GS300 RWD, '07 Camry SE V6 auto, '91 190E 2.6 auto
I wonder if a slight loss in vacuum (with vaccum assist brakes) when applying the brakes heavily would also be a contributing factor?
Old 11-22-2002, 06:59 PM
  #6  
MBWorld Fanatic!
 
Matt230K's Avatar
 
Join Date: Sep 2002
Location: Ohio
Posts: 3,145
Likes: 0
Received 0 Likes on 0 Posts
2010 C300 4matic
peet, i haven't noticed exactly what you are describing. But by working at the dealer, I drive a lot of the '03s around, usually short distances. I do notice some weird feelings when I lift off the gas after acclerating a short distance. So I guess it is normal, especially after what everyone else has said.
Old 11-22-2002, 10:57 PM
  #7  
MBWorld Fanatic!
 
Outland's Avatar
 
Join Date: May 2002
Location: The blue white rock, third out.
Posts: 2,916
Likes: 0
Received 1 Like on 1 Post
2002 C230 Coupe(M111)
The behavior is very normal.

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


You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Need help - car in shop - weird hard brake/idle problem



All times are GMT -4. The time now is 08:30 PM.