What is an overev?
03-07-2008, 08:16 AM
#17
4th Gear
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I'm buying an 03 turbo with a report of 114 ignitions in level 2 over rev. The pre-buy inspection from a qualified Porsche dealer was fine other than this report. Should I be overly concerned?
03-07-2008, 03:48 PM
#18
Rennlist Member
That may only have been 1 missed shift.
As far as I am concerned when purchasing a used car, 1 level 2 is enough. Even if the engine shows no ill effects, it is a possible symptom for other abuses, lack of care, or of the car being badly driven. I'd walk away from it.
As far as I am concerned when purchasing a used car, 1 level 2 is enough. Even if the engine shows no ill effects, it is a possible symptom for other abuses, lack of care, or of the car being badly driven. I'd walk away from it.
My previous 993 and current 996 both cut out at around the redline, I am wondering how it is possible to get to these high revs?
03-12-2008, 01:54 AM
#20
Drifting
What exactly are the two(2) over-rev ranges for the 996? I have seen the 6 ranges for the 997, with their corresponding RPM ranges, posted many times. However, I do not recall seeing a post which listed the 2 ranges for the 996/986 engines.
03-12-2008, 02:41 AM
#21
03-12-2008, 04:11 AM
#22
Drifting
For those looking to buy 996s or 997s, I would recommend buying the $250 USB Durametrics ECU reader. Plugging into the OBDII connector in the driver's footwell with this "dongle" connected to your laptop will give you plenty of information on the car. It is fun to go plug it into cars on the showroom floor... I call it a cheap Pre-PPI...
Oh - and for those interested in 997s. Porsche got "smart" and decided to add a level of subjectivity to help void warranties for abuse. The 6 ranges tracked on the 997 start well below red-line. This lets them see how hard you run the car BELOW the rev limiter so that they can cite patterns of abuse.
Big brother is watching... I guess the only upside is for those looking to buy a used 997. At least we can transparently see how hard the car was driven based on the tracked data....
-Blake
03-12-2008, 03:08 PM
#23
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The higher revs come from "mechanical" over revs. The wheels are spinning and drive the transmission through a low gear to cause the motor to spin over it's rev limit. These over revs are not caused by fuel and ignition but rather by mechanical drive from the wheels. Make sense?
03-12-2008, 04:35 PM
#24
Banned
Let's say I rarely redline the car... is this "abuse"? fun stuff to think thru.
btw, i always slightly pause in neutral and use the proper shifting hand position to minimize margin for error. it would suck to type 2 over rev!
03-12-2008, 05:23 PM
#25
Drifting
I am aware of the fact that they exist, I believe most of us here are aware that there are over-rev ranges. My question was: What are the numerical values of the 2 over-rev ranges for the 996?
I have seen the ranges posted many times for the 997 but I cannot recall seeing the ranges listed for the 996. Does anyone know what they are?
03-12-2008, 05:36 PM
#26
Drifting
+1. Type 1 is a bump against the rev limiter and measure "ignitions". Purely harmless, but does indicate to the mechanic just how "hard" the car has been driven around redline. A Type 2 indicates that the rev limiter (or throttle cut-off of the gasoline) could not contain/limit a high-RPM experience... By high RPM, I mean several thousand RPMs above redline. This is usually caused by so-called "money shifts" - 5th gear to 2nd gear (missing 4th). Personally, I would avoid ANY car with a Type 2 overrev. The car might still be running, but the engine did suffer abuse and is more likely to have problems over time. (Plenty of threads on this if you search)
For those looking to buy 996s or 997s, I would recommend buying the $250 USB Durametrics ECU reader. Plugging into the OBDII connector in the driver's footwell with this "dongle" connected to your laptop will give you plenty of information on the car. It is fun to go plug it into cars on the showroom floor... I call it a cheap Pre-PPI...
Oh - and for those interested in 997s. Porsche got "smart" and decided to add a level of subjectivity to help void warranties for abuse. The 6 ranges tracked on the 997 start well below red-line. This lets them see how hard you run the car BELOW the rev limiter so that they can cite patterns of abuse.
Big brother is watching... I guess the only upside is for those looking to buy a used 997. At least we can transparently see how hard the car was driven based on the tracked data....
-Blake
For those looking to buy 996s or 997s, I would recommend buying the $250 USB Durametrics ECU reader. Plugging into the OBDII connector in the driver's footwell with this "dongle" connected to your laptop will give you plenty of information on the car. It is fun to go plug it into cars on the showroom floor... I call it a cheap Pre-PPI...
Oh - and for those interested in 997s. Porsche got "smart" and decided to add a level of subjectivity to help void warranties for abuse. The 6 ranges tracked on the 997 start well below red-line. This lets them see how hard you run the car BELOW the rev limiter so that they can cite patterns of abuse.
Big brother is watching... I guess the only upside is for those looking to buy a used 997. At least we can transparently see how hard the car was driven based on the tracked data....
-Blake
That is very interesting info. about the 997s data acquisition. Thanks.
03-12-2008, 08:25 PM
#28
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The 996 (unlike the 997) records types of over rev, not ranges. That is why you haven't seen ranges reported.
With the 996 the over rev types (1 and 2) refer to HOW the over rev occurred:
1 - throttle incurred over rev
2 - mechanical over rev. (as defined above)
type 1 will not cause damage, that is why the fuel cut off exists prior to the point where damage will occur.
type 2 can go from no damage (unlikely) to mild (float the valves) to severe damage (break a rod)
I do not believe that the 996 keeps such detailed tattle info on the type 1 over rev as the 997. (i.e. no demerits) It just counts how many times it has occurred (not sure if it counts how many ignitions occurred during, i.e. how long)
With the 996 the over rev types (1 and 2) refer to HOW the over rev occurred:
1 - throttle incurred over rev
2 - mechanical over rev. (as defined above)
type 1 will not cause damage, that is why the fuel cut off exists prior to the point where damage will occur.
type 2 can go from no damage (unlikely) to mild (float the valves) to severe damage (break a rod)
I do not believe that the 996 keeps such detailed tattle info on the type 1 over rev as the 997. (i.e. no demerits) It just counts how many times it has occurred (not sure if it counts how many ignitions occurred during, i.e. how long)
03-13-2008, 01:55 AM
#30
Drifting
-Blake