I had an engine over-rev experience with my 2014 Cayman S MT that has me both confused and worried. Not sure how this happened, but I was turning into my development after stopping for traffic, shifting from 1st to 2nd, doing less than 20 mph. All of a sudden I hear this horrendous revving, like a motorcycle passing me at high speed and I glance out to see and then I realize it's ME and I look down just in time to see the tach hit approx. 8400 rpms. I immediately let up on the throttle. Not sure if I mistakenly shifted into neutral and let the clutch out, but my foot pressure on the throttle was low as it would be for that shift and shouldn't have caused it to rev that high even if I was in neutral. It's been about a month, car sounds and drives normal, but I'm worried something is compromised/damaged that I don't know about. Any insight or information on this would be greatly appreciated. Thanks.
Engine Over-Rev
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If you were simply depressing the throttle, you can't over-rev sufficiently to damage anything, assuming oil is up to temp. There is a rev limiter to prevent damage. If you miss a downshift then it's possible to mechanically over-rev the engine and cause damage. But just applying throttle should not be an issue. If you need peace of mind get a DME readout next time you have it serviced.
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This. If someone in your area has a Durametric they can pull the report for you. There are a number of overrev zones but you won’t be in any of the damage-causing ones.
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zedcat is correct. Worst case is a Level 1 over-rev on the DME report. It's nothing. The limiter protects the engine.
The danger is a downshift to the wrong gear when you meant to upshift. Don't worry about it.
The danger is a downshift to the wrong gear when you meant to upshift. Don't worry about it.
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Not really since, if you need warranty work that could be caused by over-revs (almost any engine work), they'll pull one anyway. But you'll pay more at a dealer, so find an indie. Or just ignore it and hope there's no damage.
I'd be more concerned how you accidentally over-reved. Might be some other problem with the accelerator. I've run into the rev-limited under hard acceleration, but it is hard to see how it happened in the situation you described. Even an accidental downshift at 20MPH isn't going to over rev.
Can't overrev the engine with the throttle, so no worries
. However, if you hit the rev limiter (which I'm sure you did), expect a level TWO (not 1) overrev, due to Porsche not changing the stupid levels when they raised the rev limit on 9A1 engines. Never stored the overrev levels when I've seen them, but a level 1 is reached even before the 7,600 rpm redline, and a level 2 between redline and the 7,800 rpm rev limiter. The overrev report is shown in ignition cycles (1 every 2 engine revolutions), FYI, so don't freak out by a relatively large number. Just convert the number into seconds, to know if you're dealing with just an occasional near-redline event, or a tracked car. Bottom line is unless you see a #3, zero issues; 1s and 2s are perfectly acceptable.
As a final comment, for some reason, the rev counter on my brother's 2015 BGTS is way laggier than on my 2016 CGTS. By that I mean exactly what you saw on your car: your needle swinging past the actual engine revs. Or in case of my brother's car, the needle noticeable slower and laggy when PDK does a shift, especially from 1 to 2, where there's a lot of spread. On my car the needle is instant, which I really like. My take is when Porsche changes the gauge color and/or needles, necessitating to remove the needle (he has the carmine red package with white needles), they can't restore the original tension of the needle spring. Curious if your car has any such option. My car has the stock configuration, which is black gauges with orange needles (the best by far IMO, since you can't see the ugly holes for idiot lights, and it's the most visible setup, day or night).
. However, if you hit the rev limiter (which I'm sure you did), expect a level TWO (not 1) overrev, due to Porsche not changing the stupid levels when they raised the rev limit on 9A1 engines. Never stored the overrev levels when I've seen them, but a level 1 is reached even before the 7,600 rpm redline, and a level 2 between redline and the 7,800 rpm rev limiter. The overrev report is shown in ignition cycles (1 every 2 engine revolutions), FYI, so don't freak out by a relatively large number. Just convert the number into seconds, to know if you're dealing with just an occasional near-redline event, or a tracked car. Bottom line is unless you see a #3, zero issues; 1s and 2s are perfectly acceptable. As a final comment, for some reason, the rev counter on my brother's 2015 BGTS is way laggier than on my 2016 CGTS. By that I mean exactly what you saw on your car: your needle swinging past the actual engine revs. Or in case of my brother's car, the needle noticeable slower and laggy when PDK does a shift, especially from 1 to 2, where there's a lot of spread. On my car the needle is instant, which I really like. My take is when Porsche changes the gauge color and/or needles, necessitating to remove the needle (he has the carmine red package with white needles), they can't restore the original tension of the needle spring. Curious if your car has any such option. My car has the stock configuration, which is black gauges with orange needles (the best by far IMO, since you can't see the ugly holes for idiot lights, and it's the most visible setup, day or night
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So, have another question on this issue. Rev limiter works by limiting fuel intake or ignitions? How does the tach respond? Can you depress the throttle as much as you want and the engine won't exceed 7600 RPM and the tach won't register above 7600 RPMs?
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I agree. Porsche has taken what I view as a ridiculous official position in its hypersensitivity to overrevs. This may be because I know I have some, but I would be willing to bet that a minuscule portion of cars with level 4’s ever experience engine failure as a result. Still, owing to Porsche’s stance, I’d have the DME check done by an indie.
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I'm not sure how Porsche does the rev-limiting, but most manufacturers use ignition to limit over-revs. If you gradually rev to redline, the rev-limiter will prevent any over-rev. If you fully depress the throttle from idle, the momentum of the rotating components may take the revs a few RPMs beyond the red line. (But certainly not into range #3 or #4) As far as how the tach responds, that depends on which needle you have and how sensitive the gauge is. (See the post a few above.)
The tach reads engine speed, regardless of whether or not the car is in gear. The only way that you could have reached 8400 RPM in neutral is if your rev limiter is defective. I'm ruling out the pssibility that you inadvertently shifted into first, since that is a difficult gear to downshift into. So you either misread your tach or you have a defective rev limiter. Also, if you were right about your car speed of about 20 MPH, then you must have been in neutral since a car speed of 20 MPH is nowhere near red-line in first gear.
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