08-10 SS Turbocharged General Discussion Discuss the 2008 - 2009 Chevy Cobalt SS Turbocharged. On sale since the second quarter of 2008.

head damage

Thread Tools
 
Search this Thread
 
Old Jul 13, 2011 | 06:08 PM
  #26  
ronn's Avatar
Senior Member
iTrader: (3)
 
Joined: 09-30-09
Posts: 2,532
Likes: 0
From: Los Angeles
Originally Posted by gotboost?17
princess u r so wrong lol
For sure..

Read this:

8th Generation Honda Civic Forum - View Single Post - Over Rev Protection

An RPM limiter can only prevent you from accelerating across a threshold where you're over-revving. Once you downshift into a gear that causes you to over-rev, the gears are physically forced to spin at that speed. Electronics can't stop that

BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3) - View Single Post - over revving?

Synchronizers only match the gear and engine speed related to the number of axle rotations. The limiter has no control over the synchronizer so if you pop it from 6 to 3 at 110 you are sure as hell gonna over-rev. When accelerating if the limiter detects the engine has hit redline then it closes the throttle body to slow down the engine but it can't do this during a downshift because it has nothing to do with the throttle body. Word to the wise, the way to avoid this when downshifting is to only downshift one gear at a time and do a heel-toe so that the car is slowing down at the same time you are downshifting.
__________________
Reply
Old Jul 13, 2011 | 06:11 PM
  #27  
ecot3c inside's Avatar
Senior Member
iTrader: (11)
 
Joined: 03-31-10
Posts: 4,212
Likes: 0
From: Chicago, IL
I'm confused on how it looked like a grenade went off in your head, but you still could drive it a little.
Reply
Old Jul 13, 2011 | 09:08 PM
  #28  
rukkee's Avatar
Premium Member
iTrader: (3)
 
Joined: 08-21-06
Posts: 6,574
Likes: 0
From: Western NY
There have already been numerous mechanical over-rev's in the Cobalt community ........ not once have i hear of the PCM ripping the shifter out of someones hands to save the car lol/
Reply
Old Jul 13, 2011 | 09:11 PM
  #29  
bushman's Avatar
Thread Starter
New Member
 
Joined: 07-07-11
Posts: 12
Likes: 0
From: minneapolis mn
Dont know drove jerky under accel. but stayed steady at a steady speed. But they said cam shaft bad valves pushed up into shaft but not down against pistons, and warped head.
Reply
Old Jul 13, 2011 | 09:18 PM
  #30  
bushman's Avatar
Thread Starter
New Member
 
Joined: 07-07-11
Posts: 12
Likes: 0
From: minneapolis mn
They said that 2 and 4 cylinders were the bad ones and it was running on 2.
Reply
Old Jul 13, 2011 | 11:17 PM
  #31  
PrincessTurbo's Avatar
Senior Member
 
Joined: 05-27-09
Posts: 2,803
Likes: 1
From: In the mountains
Originally Posted by ronn
HMM..
How's the ECU gonna *block* you on a down shift? What's the electronic mechanism to accomplish that? I don't think the ECU has any control over the mechanical aspects of shifting at all. ECU can only manipulate the motor..so it can cut fuel at the rev limit.
It's speed vs acceleration .. It doesn't use the ECU as far as I know , if the trans gears rotate faster than the current speed. it pops it out ..
I;ve done it twice , Not sure why urs wouldn't do it ..

I swear to God on my mothers Grave mine does this

Last edited by PrincessTurbo; Jul 13, 2011 at 11:24 PM.
Reply
Old Jul 13, 2011 | 11:19 PM
  #32  
PrincessTurbo's Avatar
Senior Member
 
Joined: 05-27-09
Posts: 2,803
Likes: 1
From: In the mountains
Originally Posted by rukkee
There have already been numerous mechanical over-rev's in the Cobalt community ........ not once have i hear of the PCM ripping the shifter out of someones hands to save the car lol/
Yes I am one of them , But it's different when you down shift into the wrong gear , the trans is being loaded up .. Someone could prove to me it doesn't exist Ill shut up but until you can I wont

Mechanical over rev protection system do exist in other cars like Porsche I wouldn't see why the SAAB engineered trans wouldn't have something similar.

I mean GM probably wants to replace every kid's engine because they down shifted wrong once right ?

Last edited by PrincessTurbo; Jul 13, 2011 at 11:31 PM.
Reply
Old Jul 14, 2011 | 12:11 AM
  #33  
Miko's Avatar
Member
 
Joined: 12-02-09
Posts: 296
Likes: 0
From: Toronto
Originally Posted by PrincessTurbo
I mean GM probably wants to replace every kid's engine because they down shifted wrong once right ?
That is why they record the highest RPM reached by the engine in the ECU. It is possible to tell what the max RPM was ever when they hook up to the ECU. They could then say "Sorry, you over-revved it which if you read your manual it says you are no longer covered".

The Stage 1 kit includes a higher limit AND a softer limiter function. If you look up some of the Q&A sessions about the CSS GMS1 on GMTunerSource they specifically mention the softer limiter. Maybe under certain conditions it is possible to easily rev past 6500?
Reply
Old Jul 14, 2011 | 02:45 AM
  #34  
ronn's Avatar
Senior Member
iTrader: (3)
 
Joined: 09-30-09
Posts: 2,532
Likes: 0
From: Los Angeles
Originally Posted by PrincessTurbo
It's speed vs acceleration .. It doesn't use the ECU as far as I know , if the trans gears rotate faster than the current speed. it pops it out ..
I;ve done it twice , Not sure why urs wouldn't do it ..

I swear to God on my mothers Grave mine does this
Sorry, I don't buy that explanation.

There no way the shifter or tranny *knows* what the revs are or what the speed is. The gear box will accept any input you give it, that's why a misplaced downshift can over rev the motor instantly....the tail is wagging the dog so to speak. If you floor the motor beyond a point, the ECU will sense engine revs and can instantly cut fuel/ignition. Unless you can explain to me HOW you get locked out of a down shift, I say you're wrong here.
Reply
Old Jul 14, 2011 | 12:03 PM
  #35  
rukkee's Avatar
Premium Member
iTrader: (3)
 
Joined: 08-21-06
Posts: 6,574
Likes: 0
From: Western NY
Originally Posted by PrincessTurbo
Yes I am one of them , But it's different when you down shift into the wrong gear , the trans is being loaded up .. Someone could prove to me it doesn't exist Ill shut up but until you can I wont

Mechanical over rev protection system do exist in other cars like Porsche I wouldn't see why the SAAB engineered trans wouldn't have something similar.

I mean GM probably wants to replace every kid's engine because they down shifted wrong once right ?
There was a post here not long ago where some one went to shift into 3rd and it went right into 1st without any problem .... so I'm pretty sure there isn't any type of downshift protection on these cars. No one is going to try and prove you wrong by "money shifting " their car into a mechanical over rev lol.
Reply
Old Jul 14, 2011 | 01:55 PM
  #36  
sponge14's Avatar
Senior Member
 
Joined: 03-14-09
Posts: 1,039
Likes: 0
From: Anna, TX
Originally Posted by PrincessTurbo
Someone could prove to me it doesn't exist Ill shut up but until you can I wont

Mechanical over rev protection system do exist in other cars like Porsche I wouldn't see why the SAAB engineered trans wouldn't have something similar.

I mean GM probably wants to replace every kid's engine because they down shifted wrong once right ?
First, it's impossible to prove something doesn't exist. Second, people can and have downshifted into the wrong gear which sends the engine into an uncontrollable over rev.
Reply
Old Jul 14, 2011 | 02:28 PM
  #37  
cobaltsssc760's Avatar
Senior Member
 
Joined: 10-30-07
Posts: 587
Likes: 0
From: CALI
my car will not go into first if im not at a stop i dont understand how people are doing this

the trans will not just accept any input you try and give, a misplaced downshift is caused by driver error and brute force
Reply
Old Jul 14, 2011 | 02:39 PM
  #38  
PrincessTurbo's Avatar
Senior Member
 
Joined: 05-27-09
Posts: 2,803
Likes: 1
From: In the mountains
Originally Posted by cobaltsssc760
my car will not go into first if im not at a stop i dont understand how people are doing this

the trans will not just accept any input you try and give, a misplaced downshift is caused by driver error and brute force
This^^ My car won't let you go from 5th to 2nd USUALLY at a certain speed unless a synchro is broken. Unless you use the almighty john force shift..... Maybe it's not supposed to do that then ...weird

Originally Posted by rukkee
There was a post here not long ago where some one went to shift into 3rd and it went right into 1st without any problem .... so I'm pretty sure there isn't any type of downshift protection on these cars. No one is going to try and prove you wrong by "money shifting " their car into a mechanical over rev lol.
Do it make a vid I'll give you a dollar

Last edited by PrincessTurbo; Jul 14, 2011 at 02:42 PM. Reason: Automerged Doublepost
Reply
Old Jul 14, 2011 | 03:12 PM
  #39  
Wangspeed's Avatar
Senior Member
iTrader: (2)
 
Joined: 10-22-09
Posts: 3,145
Likes: 2
From: Northern Virginia
Originally Posted by PrincessTurbo
Yes I am one of them , But it's different when you down shift into the wrong gear , the trans is being loaded up .. Someone could prove to me it doesn't exist Ill shut up but until you can I wont

Mechanical over rev protection system do exist in other cars like Porsche I wouldn't see why the SAAB engineered trans wouldn't have something similar.

I mean GM probably wants to replace every kid's engine because they down shifted wrong once right ?
You are horribly, horribly confused. There is no over rev protection available in a manual shift transmission. Computer controlled sequential will prevent this in something like a GTR, since the ECU just won't let you downshift. In a true manual transmission, if you're at the top of third gear, and you accidentally grab second gear instead of fouth, kiss your motor goodbye. There is no "over rev protection". Just like everyone is telling you, the ECU has no way of taking your hand, and making you shift the **** out of the wrong gear. There is no fuel cut to help you. There is no ECU control to help you.

Short shifters will make money shifting EASIER to do. That's right. Got a short shifter? Higher chance of money shifting.
Reply
Old Jul 14, 2011 | 03:22 PM
  #40  
Rissa's Avatar
Senior Member
 
Joined: 05-06-08
Posts: 24,605
Likes: 1
From: So Cal
Good thing the dealer took care of you!
Reply
Old Jul 14, 2011 | 04:52 PM
  #41  
ronn's Avatar
Senior Member
iTrader: (3)
 
Joined: 09-30-09
Posts: 2,532
Likes: 0
From: Los Angeles
Originally Posted by Wangspeed
Short shifters will make money shifting EASIER to do. That's right. Got a short shifter? Higher chance of money shifting.
We already have a short shifter of sorts in stock form and I like it... that's why I never wanted an aftermarket one.
Reply
Old Jul 14, 2011 | 04:55 PM
  #42  
ronn's Avatar
Senior Member
iTrader: (3)
 
Joined: 09-30-09
Posts: 2,532
Likes: 0
From: Los Angeles
Originally Posted by cobaltsssc760
my car will not go into first if im not at a stop i dont understand how people are doing this

the trans will not just accept any input you try and give, a misplaced downshift is caused by driver error and brute force
I can easily put mine in 1st coating very slowly...easy as pie.
Reply
Old Jul 14, 2011 | 05:50 PM
  #43  
Wangspeed's Avatar
Senior Member
iTrader: (2)
 
Joined: 10-22-09
Posts: 3,145
Likes: 2
From: Northern Virginia
Originally Posted by ronn
I can easily put mine in 1st coating very slowly...easy as pie.
Same. I do this all the time when I need to slow to a crawl. I do double clutch + heel/toe on the way down to be nice to my gearbox though.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
taintedred07
2.0L LNF Performance Tech
32
May 28, 2022 03:47 AM
ineedacobaltss
Parts
16
Nov 7, 2015 02:25 PM
HEATON
Parts
12
Oct 16, 2015 07:21 PM
Trav3480
Problems/Service/Maintenance
0
Oct 1, 2015 08:17 PM
Jesse
Problems/Service/Maintenance
2
Sep 28, 2015 12:51 PM




All times are GMT -4. The time now is 02:47 AM.