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my car has zero over revs in any range- I use the car and all the revs and the rev limiter has cut in many times plus I have had it from near new so I don't agree with the above statement. You can only over rev by dropping a gear to early or selecting a lower gear at high revs by mistake.
Rev ranges - 997 GT3:
Create the VAL before deleting the fault memory. Overspeed events are documented as follows in the VAL:
Rev range 1: 8,400 -1 ... to 9,200 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 2: 9,200 -1 ... to 9,400 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 9,400 -1 ... to 9,600 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 9,600 -1 ... to 10,000 -1
⇒ Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 10,000 -1 ... to 11,000 -1
⇒ Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 11,000 -1
⇒ Engine damage has generally occurred.
Wouldn't your states local BAR have something aginst this- swapping ecu's out to to record potential over rev's amongst other parameter's? If Porsche was smart about this... If they were smart about it Porsche will have kept su h parameters seperate from the ECU simply just keep if in some form oc flash memory off of the ECU just fof such cases. So people would not be able to cheat the ecu of saving and keeping data.
But then I could be completely wrong about the whole situation. As "They Say, Only one way to find out... Or if you are lucky fine someone who is an expert in these matters.
Originally Posted by Loess
It was possible to delete over revs on older ecm software versions. I'm not sure about current ecm's.
I would be very suspicious of a car with 0 ignitions in range 1 and 2.
We've done it with a 997.1, the owner blew his engine and bought a new one, after that we flashed the ECU and deleted the range history. 100% certain it can be done in 987.1 and 997.1
my car has zero over revs in any range- I use the car and all the revs and the rev limiter has cut in many times plus I have had it from near new so I don't agree with the above statement. You can only over rev by dropping a gear to early or selecting a lower gear at high revs by mistake.
Rev ranges - 997 GT3:
Create the VAL before deleting the fault memory. Overspeed events are documented as follows in the VAL:
Rev range 1: 8,400 -1 ... to 9,200 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 2: 9,200 -1 ... to 9,400 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 9,400 -1 ... to 9,600 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 9,600 -1 ... to 10,000 -1
⇒ Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 10,000 -1 ... to 11,000 -1
⇒ Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 11,000 -1
⇒ Engine damage has generally occurred.
Here is hard data on "naturally occurring" overrevs up to R4 (!) on my GT2. Now, the range for turbos is much lower than NA GT3s, but I think my data does support the idea that there should be at least R1 and R2s on most cars, aside from those that are total museum pieces.
Regarding overrevs and GT2s, Range 4 overrevs (7400-7900) are not necessarily misshifts (although, of course, they could be). In my case, they often occurred at the track on a long straight where I am trying to go really fast and shift to a higher gear as quickly as I can. I engage the clutch to shift to the higher gear but my foot isn't totally off the gas, so I rev the engine basically in neutral. (I recognize this isn't great, but it's not a misshift) The engine commonly revs into the 7000s and occasionally just around 7400.The pictures attached contain data showing this from one of my laps. This happened hundreds of hours ago (I haven't tracked the car in years). I have had zero issues.
All I am trying to say (and fair criticism, I have a horse in this race) is that R4 overrevs are absolutely not a sure sign of a misshift, and if they happened hours ago are likely a non-issue.
The Turbo overrev classifications apply to the GT2:
Notice the max RPM on lap 8
The "+" on this map is the location of the 7407 cycle. Right in the dead middle of the straight:
I believe turbos and GT2 trigger the lower rangers much easier than GT3's and RS's. I am not sure why but theres loads on the subject over in the turbo forums.
a) I think miles are tracked in odo module. New ECU will still report proper miles. over revs and hours would be 0 unless properly programmed otherwise.
b) Unlike NA, GT2's (and I assume Turbos) will register 3's (and a possible 4) all day just from rev limit bounce - and sometimes even with a proper shift before cut-out. 997 GT2's (and I assume Turbos) seem to jump about 300 RPM when shifting at wot (even after your foot is off the gas). Some very experienced Turbo gurus suggest that this is due to the inertia of the heavy dual mass flywheel in the and not a throttle response/software thing (or a slow response from the pilots right foot). It is my understanding that those who have replaced with single mass 4.0 or other FW's do not experience the jump, so the explanation makes sense. Nature of the Beast.
Some very experienced Turbo gurus suggest that this is due to the inertia of the heavy dual mass flywheel in the and not a throttle response/software thing (or a slow response from the pilots right foot).
That would exactly explain the data I show above. Thanks for sharing!
you get overrevs when you take it to redline, so if you find a car without any 1st level overrevs, it's because a) something is fishy, or b) it was never driven to fuel cut.
Originally Posted by Loess
It was possible to delete over revs on older ecm software versions. I'm not sure about current ecm's.
I would be very suspicious of a car with 0 ignitions in range 1 and 2.
Originally Posted by Ur20v
my car has zero over revs in any range- I use the car and all the revs and the rev limiter has cut in many times plus I have had it from near new so I don't agree with the above statement. You can only over rev by dropping a gear to early or selecting a lower gear at high revs by mistake.
Rev ranges - 997 GT3:
Create the VAL before deleting the fault memory. Overspeed events are documented as follows in the VAL:
Rev range 1: 8,400 -1 ... to 9,200 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 2: 9,200 -1 ... to 9,400 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 3: 9,400 -1 ... to 9,600 -1
⇒ Maximum permitted engine speed exceeded; engine damage possible.
Rev range 4: 9,600 -1 ... to 10,000 -1
⇒ Maximum permitted engine speed clearly exceeded; engine damage probable.
Rev range 5: 10,000 -1 ... to 11,000 -1
⇒ Maximum permitted engine speed very clearly exceeded; engine damage very probable.
Rev range 6: over 11,000 -1
⇒ Engine damage has generally occurred.
Originally Posted by Ur20v
PS free reving an engine to the rev limiter wouldn't cause a range one on a GT3.
I sold a few 997RS, one had 17 ignitions in Rave range 1, the rest had zero over revs. On both ECU's ;-)
try it and see... there is more drag i.e power trying to slow the engine then there is ineria trying to maintain motion or acceleration by a large delta. When you remove fuel and or spark i.e the power to accel the engine the compression and drag from pistons, rings, bearings etc are like putting the brakes on the engine. Same goes for the car itself, look at accel plots between gear changes the car stops accelerating due to tyre and aero drag.
Some very experienced Turbo gurus suggest that this is due to the inertia of the heavy dual mass flywheel in the and not a throttle response/software thing (or a slow response from the pilots right foot).
They may be experienced with a turbo but certainly not with physics. That's not how inertia nor F=MA works. You CANNOT accelerate mass without applying force. That flywheel will not accelerate itself and will spin no faster than the direct output from the ICE provided it. The only other additional force that could be applied would be gravity (or a collision). Even the cork screw is not steep enough to provide gravity assistance to overrev an ICE in a 911 (given avg 911 wt/pwr/etc.) Countering forces from wind and tire resistance will almost always be greater than an assist by incline when at speeds where misshifts occur.
Essentially people making the same argument that inertia from the flywheel is what caused the overrev are making the same argument as people who say the car 'sped up' when spinning from asphalt to grass. It's a poor understanding of physics.
I think it typically happens because the rev limiter is not actually a hard cut, it combines spark and fuel cuts to reduce power, not cut it entirely. Which is why its probably common to have 1&2 for tracked vehicles, where you shift at redline, drive on redline.
03-06-2016, 09:40 PM
