Need help - car in shop - weird hard brake/idle problem
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MBWorld Fanatic!
Joined: Jun 2002
Posts: 1,249
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From: Chicagoland, IL
09 C63
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
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
MBWorld Fanatic!
Joined: Aug 2002
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From: York, PA
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.
MBWorld Fanatic!
Joined: Nov 2001
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From: Gaithersburg, MD
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.
MBWorld Fanatic!
Joined: Aug 2002
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From: York, PA
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.
MBWorld Fanatic!
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From: Ohio
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.
