alexb76

So, while doing my oil, filter, brake service I had them scan for over-revs, here are the results:

Range 1: 3691
Range 2: 949
Range 3: 79
Range 4: 4
Range 5: 0
Range 6: 0

It looks ok I guess, but shows I drive to the redline quite a bit

Should I be worried about that 4 iginitions in range 4 (for warranty purposes)?

gota911

What time (engine hours) was the last ignition in each range? If the Range 4 was a while ago (i.e. not yesterday), then you probably have nothing to worry about. I wouldn't worry about it.

Spiffyjiff

youre fine.

StanThePorscheFan

So, these numbers are the result of you just hitting the rev limiter? I recently had a conversation with my service advisor on this subject and according to him, you should only be getting range 1 and very few ignitions in range 2 when hitting the limiter.
If you are getting range 4, then the limiter is not doing what it's supposed to do, protect the engine.

Quadcammer

from my understanding, its an inertia issue. In first/2nd gear when the engine is revving quickly, the momentum of the rotating assembly simply carries the revs higher even during fuel cut.

4 ignition cycles is nothing, you are fine.

Fahrer

It looks like one ( single) bad downshift ( 3&4 ranges)

Spiffyjiff

correct. the rev limiter can only protect from incorrect throttle input (i.e. trying to step on the gas past redline), it cannot protect from an incorrect downshift - or the "money shift", as we like to call it - where a gear ratio combination could potentially push the revolutions far beyond redline.

FYI, there are 3 ignitions per revolution, and range 4 is 7900-8400 RPM i believe? therefore your engine was at range 4 for less than .03 of a second...youre fine. get out and drive.

Quadcammer

thats correct about the mechanical overrev forced by the transmission, but even on a straight single gear acceleration, there seems to be sufficient inertia to push the revs quite a bit beyond the limiter.

If this range 4 happened more than a couple miles ago and the car runs fine, I wouldn't give it another thought.

rebattery

sometimes you just don't need to know!

No HTwo O

Yes, you have a problem. Mainly for 2 reasons:

1) Try explaining the over-revs to the next potential, smart, buyer of your car. This will hurt your resale value.

2) Porsche can use the range 4 over-revs to deny a warranty claim. Maybe your warranty is over.

To get the range #3 and range #4 over-revs on your car, you either:

1) Missed a downshift

2) Spun on the track, and spun engine backwards

Edgy01

Those numbers are nothing. That car has been driven very conservatively. We have discovered that low numbers (less than 5) in any of the ranges can be suspicious in origin, and often caused by spurious signals, and not by any excessive rpm event.

alexb76

Thanks, the 4 ignitions in range 4 is literally 3ms which I am surprised could have even be captured. But, I certainly hope they won't use that as an excuse to deny warranty.

I think the Range 3 is definitely result of one mis-shift that I do remember.

alexb76

I really don't think my over-revs are anything to worry about or have to explain. I searched around and there are many posts with much worse ranges. Range 1-2 totally can happen when u shift around red-line.

I do remember one mis-shift that should have caused range 3, but that definitely is not gonna affect warranty. The range 4 *might*, although 4 ignitions in 8000 RPM is like 0.01 of a second most likely a mis-read and I hope it should be fine, at least I have a good argument to make.

Will be careful with shifting from now on!

No HTwo O

This is how you got into range #4 too, then. If you had a warranty issue that can be linked to the over-revs in range #4 Porsche has every right to deny your claim.

No HTwo O

Not a mis-read, for sure. Wishful thinking. You were well over 8,000 RPM too. Here are the rev ranges:

A 997-1 DME records the following rev ranges:
Range 1: 7300-7500 RPM
Range 2: 7500-7700 RPM
Range 3: 7700-7900 RPM
Range 4: 7900-8400 RPM
Range 5: 8400-9500 RPM
Range 6: 9500-11000 RPM