Just banged redline
Thread Starter
Pro
Joined: Mar 2008
Posts: 640
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From: Wappingers Falls New York
IMHO, I wouldn't worry about checking the CR...a leakdown test might tell you something, but I'd suspect you'd see a code and/or noise and performance issues if there was anything worth worrying about.
Race Director
Joined: Mar 2001
Posts: 11,405
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From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Just letting everyone know that I pulled the pushrods and checked them, everything was good. There was a small bend in a few rods but only about 1mm, barely noticeable. Buttoned the car up and took her for a quick ride everything seems fine to me.
I think I'll take American_HP's advise and buy a lotto ticket today cause I can't believe that nothing broke.
I think I'll take American_HP's advise and buy a lotto ticket today cause I can't believe that nothing broke.
Its easy to grab 2nd when your palm is facing you because its natural to pull the shifter toward you, not straight down.
Le Mans Master
Joined: Nov 2005
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From: East Peoria Illinois
Race Director
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From: Long Island NY
St. Jude Donor '08-'09
Tech Contributor
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From: Charlotte, NC (formerly Endicott, NY)
Bill
Le Mans Master
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From: Seattle WA
St. Jude Donor '14
As a new ZO6 owner and first-time 6-speed owner I found this to be key - my habit of grabbing from the side definitely caused some initial issues for me.
Le Mans Master
Joined: Nov 2005
Posts: 5,451
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From: East Peoria Illinois
this is true...all of my cars have been manuals...and they all rest in nuetral between 3rd and 4th....just pull it back..but when you are racing and crazy speed shifting...you can foul up.......human error
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Melting Slicks
Joined: Apr 2007
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From: Hereford AZ
Again, we are talking a MANUAL transmission ....
Let's take simple example .... redline is 5000 RPM and .....
1st gear redline is 20 MPH
2nd gear redline is 40 MPH
3rd gear redline is 60 MPH
(SIMPLE example ..... meant to illustrate the discussion)
Driver accelerates the car in first gear to redline .... then shifts to second gear and at redline (40 MPH) intends to shift up to third gear .....
First, let's assume that instead of shifting up ... the driver stays in 2nd gear with the accelerator pedal to the floor. The PCM (Powertrain Control Module) will use the built in rev limiter to keep the engine at 5000 RPM. The driver can keep the pedal floored all day long and (at least theoretically) the engine won't go over 5000 RPM. In the "olden days" before engine management computers I could damage my engine by simply staying on the accelerator until the engine blew up because it had no protection against such an over rev.
Now, to continue the example, the driver shifts ..... BUT .... instead of selecting third gear the driver mistakenly selects first gear .....
Well .... when the driver releases the clutch ... in this example (40 MPH shift into first) the engine speed will immediately rise to close to 10,000 RPM ...... I say "close to" because the drive wheel tires will probably lose grip with the road before the engine speed can get that high ... plus there will be some "braking" effect as the drivetrain tries to accelerate to match the 40 MPH speed .....
Manual transmissions use MECHANICAL linkages for the driver to select a gear. The only "electrical" connections to my manual tranny are for things like transmission fluid temperature sensor ...... my PCM has NO CONTROL over the gearbox ...... with enough brute force I can basically select ANY gear in the gearbox at ANY speed. I may have to fight the synchronizers ..... but it can be done.
Let's take simple example .... redline is 5000 RPM and .....
1st gear redline is 20 MPH
2nd gear redline is 40 MPH
3rd gear redline is 60 MPH
(SIMPLE example ..... meant to illustrate the discussion)
Driver accelerates the car in first gear to redline .... then shifts to second gear and at redline (40 MPH) intends to shift up to third gear .....
First, let's assume that instead of shifting up ... the driver stays in 2nd gear with the accelerator pedal to the floor. The PCM (Powertrain Control Module) will use the built in rev limiter to keep the engine at 5000 RPM. The driver can keep the pedal floored all day long and (at least theoretically) the engine won't go over 5000 RPM. In the "olden days" before engine management computers I could damage my engine by simply staying on the accelerator until the engine blew up because it had no protection against such an over rev.
Now, to continue the example, the driver shifts ..... BUT .... instead of selecting third gear the driver mistakenly selects first gear .....
Well .... when the driver releases the clutch ... in this example (40 MPH shift into first) the engine speed will immediately rise to close to 10,000 RPM ...... I say "close to" because the drive wheel tires will probably lose grip with the road before the engine speed can get that high ... plus there will be some "braking" effect as the drivetrain tries to accelerate to match the 40 MPH speed .....
Manual transmissions use MECHANICAL linkages for the driver to select a gear. The only "electrical" connections to my manual tranny are for things like transmission fluid temperature sensor ...... my PCM has NO CONTROL over the gearbox ...... with enough brute force I can basically select ANY gear in the gearbox at ANY speed. I may have to fight the synchronizers ..... but it can be done.
By the way several references to the main engine control computer can be used synonymously- Engine Control Module (ECM), Vehicle Control Module (VCM)-HP tuners, and Powertrain Control Module (PCM).
....you may also have the skip shift connection to your trans as well; but who getting picky..?
No tone meant to this e-mail; final post on this.
Last edited by vjjack04; Aug 11, 2008 at 10:14 PM.
Original Founding Member!
Joined: Jul 1999
Posts: 9,037
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From: Granby, MA
Cruise-In 1, 3, 9. 10 & 11 Veteran
Yeah, you could do that (raising price of car and complexity ... which could affect reliability) ..... but you also have taken away "driver control" ..... and I like to be in control ..... (several ex-girlfriends and wives have noticed this fault .... 
)
Let me give you an example of where your system would drive me nuts ....
Look at Laguna Seca .... come out of turn 11 and accelerate flat out through turn 1 to turn 2 .....
http://www.laguna-seca.com/pages/Track_Map
You will be close to redline in 4th gear (120+ MPH) as you approach turn 2 ..... but turn 2 is so tight that you need to exit it in 2nd gear .....
So I approach turn 2 in 4th gear ..... as I begin braking for the turn, I shift from 4th to 2nd (Right foot braking - Left foot on clutch pedal) .... as my speed falls within the range of second gear I "blip" the accelerator pedal to raise engine speed and allow the clutch to engage.
I'm now in the correct gear to "throttle steer" through turn 2 .......
Your system would require me, for some split few seconds, to choose 3rd gear ..... a complete waste of time .....
To me, driving a car is like piloting a boat .... YOU are responsible for the outcome of your trip.
If you're out in the middle of the ocean and your GPS fails ... you had better have the charts, tools (sextant and chronometer) and skills to get to a safe harbor ..... it is your responsibility.
If you're on a race track or on city streets, quit relying on "nanny" aids ..... you bought a Corvette ... freakin drive it ..... or sell it because you don't have the skills or cojones to drive it.
)Let me give you an example of where your system would drive me nuts ....
Look at Laguna Seca .... come out of turn 11 and accelerate flat out through turn 1 to turn 2 .....
http://www.laguna-seca.com/pages/Track_Map
You will be close to redline in 4th gear (120+ MPH) as you approach turn 2 ..... but turn 2 is so tight that you need to exit it in 2nd gear .....
So I approach turn 2 in 4th gear ..... as I begin braking for the turn, I shift from 4th to 2nd (Right foot braking - Left foot on clutch pedal) .... as my speed falls within the range of second gear I "blip" the accelerator pedal to raise engine speed and allow the clutch to engage.
I'm now in the correct gear to "throttle steer" through turn 2 .......
Your system would require me, for some split few seconds, to choose 3rd gear ..... a complete waste of time .....
To me, driving a car is like piloting a boat .... YOU are responsible for the outcome of your trip.
If you're out in the middle of the ocean and your GPS fails ... you had better have the charts, tools (sextant and chronometer) and skills to get to a safe harbor ..... it is your responsibility.
If you're on a race track or on city streets, quit relying on "nanny" aids ..... you bought a Corvette ... freakin drive it ..... or sell it because you don't have the skills or cojones to drive it.
Your talking racing on a track, I was simply suggesting this for a street car. But since you mentioned it, If the system was this sophisticated, there would also have to be a defeat just like "competition mode" for the traction control system. Come to think about it, this could be just incorporated into it. When you go into "competition mode" you would defeat the gear selection/overrevving option.
Intermediate
Joined: Jul 2008
Posts: 25
Likes: 0
Which and how do mods disable the PCM rpm cutoff?
OK I am not an expert in this area and would appreciate guys posting details. I have a stock 2002. I have inadvertently redlined it more than once just dealing with freeway ramps, but on mine PCM cuts off power to protect the engine. I'm assuming something in these modifications disables that feature of the PCM. Could someone explain it, just in case I ever decide to modify things?
Thanks!
Thanks!
Instructor
Joined: May 2008
Posts: 149
Likes: 0
From: Twain Harte CA
OK I am not an expert in this area and would appreciate guys posting details. I have a stock 2002. I have inadvertently redlined it more than once just dealing with freeway ramps, but on mine PCM cuts off power to protect the engine. I'm assuming something in these modifications disables that feature of the PCM. Could someone explain it, just in case I ever decide to modify things?
Thanks!
Thanks!
If you are not planning on modding your car to produce more power at higher RPMs, then you will be $$ ahead to leave the PCM rev limiter settings as they are. The rev limiter is there to protect the engine from grenading by electronically disabling ignition above the set rev limit. You can re-program the PCM to change the rev limiter's cut out threshold, but you are risking some serious damage without specific mods. Now, that being said, if you install stiffer valve springs, a high performance cam, competition or pro-stock pistons, high performance rockers and stronger pushrods, and top things off by having the engine balanced and blueprinted, you can safely raise the rev limiter settings.
I hope this explanation helps.
