8Lug

Thanks for all the responses. All the work was completed after dealer took the vehicle so I do believe they did all of it. The carfax change of ownership and service date records confirm this. Unfortunately, the DME came back with over-revs all the way through range 6 and the most recent being within an hour of running the scan. This just does't sit right with me. Regretfully think i'll have to pass.

6Mezger

8Lug

Agreed. When I questioned them on it, the sales guy said he was embarrassed and couldn't believe it himself. He said a tech must have missed a downshift when pulling the car into the service bay. I asked if it was normal for them to redline the cars when moving them around the lot. He would have had to be at or near redline to get a range 6 overrev on missed downshift. What a shame.

Skwerl

How many 6s was it, exactly? If it's under about 10 it was probably a computer glitch.

8Lug

Number of ignitions at speed > maximum speed, range 1 23718
Number of ignitions at speed > maximum speed, range 2 6541
Number of ignitions at speed > maximum speed, range 3 962
Number of ignitions at speed > maximum speed, range 4 112
Number of ignitions at speed > maximum speed, range 5 5
Number of ignitions at speed > maximum speed, range 6 4

Skwerl

Yeah, 5 range 5s and 4 range 6s is almost certainly a computer glitch...

theplings

My own experience - Porsche dealer I bought from did spark plugs/drive belt service, clutch accumulator, added clear side markers(provided originals) and filled in front bumper bracket and repainted bumper cover - all documented.

If it's a reputable dealer I can't believe they would lie about work being done.

I still did a PPI at an Indy though.

pressure ratio

I am new to the 911, so excuse me if this has been posted before. But has damage been proven due to these higher overrev ranges?

I'm not saying that bouncing the engine off the rev limiter is good for it. But I have never seen a group of car enthusiasts so concerned about cars being damaged by hitting the rev limiter. Many cars have rev limiters and many hit them quite often. I see cars on them all the time on the street and tracks. So I am curious if this is more of a Voodoo thing or if there is proof to support the fear of damage done by overrevs.

Just learning the platform and trying to understand different aspects of these cars and their owners.

Thanks

Skwerl

They are massively over hyped, particularly on old incidents. Over revs can break an engine, but it happens almost immediately.

People wring their hands based on hypotheticals but observed reality paints a different picture. Here's one way to look at it: there are a lot of 996s, 997s and 991s stretching back 20 years with "bad" over rev reports, and yet, shockingly, we never see people posting that these engines are snapping rods or throwing pistons or exploding into a ball of parts on the highway. Quite the opposite, actually - tons of enthusiasts own these cars and never have any issues that don't also occur on babied cars. Heck, the 100% real fact that you can find actual cars with range 5s from 300 hours ago still running strong goes to show that they can keep going for 300+ hours without problems if they survive the initial incident.

Given the amount of 911s showing these over revs, it's safe to assume that a good percentage of the manual sports cars being sold without reports have undocumented over revs as well, and even then, actual engine catastrophes are rare. The only difference is the owner is blissfully unaware he's driving a ~*ticking time-bomb*~.

DME reports are best used as a general diagnostic to see if Mr. Only Driven by an Old Lady to Church Services is telling the truth, but beyond that, most of the hysteria isn't based on the evidence before us. If a thorough PPI tells you it's a good car that's running strong, then that's the car you're buying, not an abstract "this could blow up any second, despite that never happening" theorycar.

Edit: For your knowledge, past about range 2-3, you don't get over revs from just bouncing off of redline, it usually indicates a missed shift. ECU tunes can also raise the limiter, making it trivially easy to rack up range 1-2 just by running to redline.

atcbi5

pressure ratio

The manufacturer has a hard rev limiter for a reason. So the car is held under the threshold they deem unsafe for the motor. Which I am sure includes a margin of error factored into it. So the accidental hitting of the rev limiter is not the end of the world. I think the phrase "Over-rev" report sends people in the wrong direction right off the bat. lol

Do these rev ranges all have different soft rev limiters that get progressively harder as they go up? And what is the final hard limiter set at from the factory?


And for the record, my car had 64K miles and had 1279 in range 1, 58 in range 2, and zero in ranges 3-6. So I am truly just trying to learn.

Skwerl

That's the rev limiter. The more mundane "redline" over revs are simply from inertia spinning the crank past the rev limiter. Pretty easy to do in Turbos since 1st runs out fast. That inertia can only go so far, though, and beyond that you see missed shifts inducing the over revs, like accidentally downshifting to 2nd at 100mph. You could feasibly botch a shift so badly that you spun it at 11,000rpm briefly, but that would undoubtedly break everything right there on the spot. Each range has a hard-encoded value where those RPMs are registered, which is why it can get tricky if you have a tune that raises the redline limiter into that range 1/2 zone.

Here's how it usually goes down:

pressure ratio

ok. If the bottom of rev range 1 is 6800, and where the hard rev limiter is at, you are talking more than rotating assembly inertia to spin the motor past 9,000,

I was under the impression the lower rev ranges were soft limiters and a hard limit at some point around somewhere in rev range 4 or 5. So I had a hard time imaging an engine revving to ranges 5 & 6 just by having your foot on the gas. But that isn't the case. It is more about missed downshifts where the car's weight and gearing are causing the engine to spin that high.

So I can see where an over-rev in ranges 5 & 6 are more worrisome.

Thanks for the info. I appreciate it!

Skwerl

Yeah, recent legitimate 5s and 6s are the ones to be concerned about since what happened in those videos is what happened to the car. If someone did that 15 minutes ago, it's wise to give the car some time to make sure it's fine. I emphasize "legitimate" because it has been shown many times that the DME readout is not infallible, and can easily glitch fake low numbers of the upper ranges.

nzskater

To be clear though, the chances are that a small number registered at range 5 and 6 are likely errors, not genuine over rev/miss shift events. If it was me and I liked the car, I'd use this data to push the price down.