Mechanical Over-Rev - How does it cause damage?
Teching In
Joined: Jul 2009
Posts: 9
Likes: 0
I just stumbled across this thread. Ironically, I have a pretty bad over-rev this weekend at Road Atlanta in my '99 C5 LS1 Corvette.
I downshifted into 3rd way to early coming down the hill into 10A and over revved the engine to about 8K.
It immediately went into some kind of limp mode almost like the traction control kicked in, but it was not on. I had to limp it off the track and thought I had blown it up. Within about 90 seconds though, it seemed to come back to life and I was able to go back out the next session and run the fastest lap of the weekend at 1:34.44.
I heard someone say that the car has 2 limiters. The first "soft" limiter is set at 6,200rpm and the "hard" limiter is somewhere much higher for cases like what I did. Any ideas on what may have happened?
Here's the video. Watch the tach and listen to the tone of the engine change when it hits about 8,000. I tried to get back in the gas after turn in, but there was no power whatsoever.
http://www.youtube.com/watch?v=H2hgX...layer_embedded
I downshifted into 3rd way to early coming down the hill into 10A and over revved the engine to about 8K.
It immediately went into some kind of limp mode almost like the traction control kicked in, but it was not on. I had to limp it off the track and thought I had blown it up. Within about 90 seconds though, it seemed to come back to life and I was able to go back out the next session and run the fastest lap of the weekend at 1:34.44.
I heard someone say that the car has 2 limiters. The first "soft" limiter is set at 6,200rpm and the "hard" limiter is somewhere much higher for cases like what I did. Any ideas on what may have happened?
Here's the video. Watch the tach and listen to the tone of the engine change when it hits about 8,000. I tried to get back in the gas after turn in, but there was no power whatsoever.
http://www.youtube.com/watch?v=H2hgX...layer_embedded
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
The PCM won't prevent the car from driving the engine up over any of the rev limiters.
11 Second Club
Joined: Oct 2006
Posts: 149
Likes: 0
At the time I put it down to a mechanical, not pcm related fault.
Here is a video of my car with what I think was a mechanical overrev. I was shifing into 4th and hit 2nd. Nothing was wrong as I pushed in the clutch fast. What kind of damage could this have caused (or possibly did cause that I dont know about).
Start watching video at 4:14, the race is at the end. It is the black LT1 Trans Am
http://www.youtube.com/watch?v=HDjCmCPHWDg
Start watching video at 4:14, the race is at the end. It is the black LT1 Trans Am
http://www.youtube.com/watch?v=HDjCmCPHWDg
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Here is a video of my car with what I think was a mechanical overrev. I was shifing into 4th and hit 2nd. Nothing was wrong as I pushed in the clutch fast. What kind of damage could this have caused (or possibly did cause that I dont know about).
Start watching video at 4:14, the race is at the end. It is the black LT1 Trans Am
http://www.youtube.com/watch?v=HDjCmCPHWDg
Start watching video at 4:14, the race is at the end. It is the black LT1 Trans Am
http://www.youtube.com/watch?v=HDjCmCPHWDg
