SAN997

Putting on my engineer cap, the log shows 2 revs in band 6, 3 in band 5 and 4 in both bands 4 and 3. I doubt the validity of this reading because it seems highly improbable that the engine could spend at most 4 revs, which is only 3 ms of time, in this RPM band. So probably this measurement is mostly an artifact, and I wouldn't be surprised if it is entirely due to noise in the signal or timing jitter in the measurement system.

It doesn't even make sense how you could possibly have 2 revs in band 6 and only 4 in band 3. The time constant of the engine due to the rotational inertia is such that the rotating velocity cannot change that fast. You would expect to see a fairly linear decrease in revs for higher bands.

Unless you have 10-50 revs in a given band, I don't think the reading is valid or a concern.

Jim Cobb

If the car you are considering is out of warranty, it comes down simply to how skittish the overrev report makes you feel, which is probably a function of how long it has been since the last one above level 3. IF, however, you are looking at a car that is still in the warranty period with revs above level 3, that car's engine warranty is worthless according to Porsche. I found this out the hard way in trying to negotiate a trade-in with two different dealers. Not only will they not certify a car with revs above level 3, they won't retail it at all, and might not even wholesale it, for fear of being caught selling a car that is technically under warranty knowing that the engine warranty is toast. This is total b.s. in my book, since such overrevs typically last only a fraction of a second, but that is P.C.N.A. policy and not subject,to dealer discretion.

Skwerl

Genuine request: Can anyone post a link to a thread or post somewhere of a car that had overrevs in 4/5/6 and then some time later had engine problems directly caused by that? I've seen a couple videos of it happening to cars on the track and the engine basically blew up right then and there, but I don't think I've ever seen first-hand accounts along the lines of "I bought this 997 with some band 5 overrevs and it threw a piston [or whatever catastrophe] 1000 miles later."

I think literally every time the topic is brought up it's in purely hypothetical/speculative terms.

Tj40

This link is helpful and worth reading - http://www.911virgin.com/porsche/rev-range-information/

To your point, quote "We recall a 996 Tiptronic Turbo that we travelled to purchase. On the surface a beautiful car but with 313 ignitions recorded in Rev Range 2, the most recent of which recorded within the last 3 operating hours, not a car we were prepared to buy. A wasted journey, but with the benefit of hindsight a narrow escape. Two weeks later we were contacted by the owner of the car who, after our viewing, had managed to find a private buyer for his vehicle. The buyers pre-purchase inspection picked up on an engine rattle, he pulled out of the sale narrowly avoiding a large bill because a week later the inter-gear failed and the engine needed to be rebuilt. We eventually got to the bottom of how ignitions were recorded past the red line. Whilst on a final blast before attempting to sell to ourselves, a moment of indiscretion racing a group of motorbikes saw the limiter exceeded whilst at full throttle down a long steep hill. The incline caused the car to travel faster than it otherwise would have done, the cars momentum taking the engine past its limiter damaging it in the process."

Now in this case clearly the problems were apparent pretty shortly after the event . The article quotes "a 50 operating hour window of danger after the point of an over rev where chains or associated inter-gear can fail or develop problems leading to costly engine work / engine rebuilds."

So engine damage 'should' be apparent pretty shorty after the event, to your point given that people on here regularly ask about DME reports and range 5/6 ignitions, those cars are out there somewhere - do they ever have problems? I don't know, maybe they just get brought by people who don't come on Rennlist??

fast1

The ignitions in ranges 3 to 6 are bogus, and caused by a computer glitch. Any Porsche tech will verify this. The overrevs in ranges 1 and 2 look plausible. They simply mean that the driver accelerated to a point where the rev limiter kicked in and gas shutoff occurred. At 8K RPM a six cylinder engine has 400 ignitions per second. So 640 ignitions could occur in just one instance of the driver hitting the rev limiter with a tiny spill over into range 2. Certainly no reason to not buy this car.

Ignitions in ranges 4 - 6 are caused by a driver engaging the wrong gear on a downshift. If the engine is running at 5K RPM in 6th gear and the driver inadvertently shifts into 2nd instead of 4th, there will probably be a minimum of a 1000 - 1500 ignitions before the driver recognizes his error. This is a mechanical overev, and shutting off the gas doesn't prevent it.

Raven 666

I Recently purchased a durametric diagnostic tool for my 06 997,s with close to 46000 klm on the dial and spent a little time today with the laptop plug into the car just to get my head around it and see what I could learn as you do,,,one thing that has got me stumped is the cars Ignition range figures ....?

So these are my ignition range figures below and was after some different opinions on what you guys think about the cars ignition range history ,,,,,I do drive the car to its full potential and can honesty understand the the figures in the first 3 ranges but the one figure in ranges 4 , 5 , 6 at 1018.4 hr has got me baffled as the previously posted information at 911 virgin .com claims that either I or the previous owner have Rev the engine to 9500rpm on a down shift ...

Are these figure correct and is it even possible to do that to an M97 with out and engine failure or damage of some kind ....also keep in mine this event happened some 360 hrs ago ,,I have had the car for 2.5 years and done almost 6000 klm of driving in that time ,,,prior to purchasing I had a PPI and there was no mention of this over rev that surely would have show up in the PPI ,,,,,,as far as I am concerned the engine runs and performs as flawlessly as the day I got it so I am putting this out to you guys what do you think of these figure ,,, Correct or some sort of anomaly



Number of ignitions range 1 2247 / 1374h


Number of ignitions range 2 222 / 1367h


Number of ignitions range 3 12 / 1366.9h


Number of ignitions range 4 1 / 1018.4h


Number of ignitions range 5 1 / 1018.4h


Number of ignitions range 6 1 / 1018.4h


Operating hours counter 1374.8

LexVan

When you bought the car 2.5 years ago, did you request a rev range report during the PPI? They are normally NOT done as routine.

When I see 1 over rev in the range counter, I assume 3 things:

1) the DME was tampered
2) the car has a tune
3) anomaly

Then you need to do your due diligence to square the deck. The rev report is only one tool in the car buying process. Not a magic tell-all-pill.

In your specific case, it looks like some anomaly since you've done 360 trouble free hours.

Keep calm, and drive on.

SAN997

One ignition is not a reliable indicator of an overrev. Moreover, it doesn't even make sense that you can have one in 4, 5 and 6. You would need 4>5>6.

Pcar416

^^ agreed

Raven 666

Yes it certainly makes no sense to me to have one in 4,5,6 just wanted to get some different view points as I feel it never hurts to hear what other thing and may have learned over the years..
@LexVan the car has never had a tune and I certainly wouldnt think any tampering of the DME has happened at any stage ....When I got the PPI done I only asked about the over Revs and never got a report done so more than likely The dealer who did the PPI just didn,t look or told me what I wanted to hear ,,,not to worried about it due to the hours that have followed with zero issues every thing is fina as far as I am concerned ...........like you said drive it and forget about it

talkenrain

I just had a PPI done on a car i was considering. Unlike the others, does this look more legit? would you walk away from this car?

Skwerl

Yikes.

I'm typically an ardent defender of the "overrevs are overblown internet hysteria" mentality but that one just had a bad money shift less than half an hour ago. I'd probably pass or revisit it after the guy puts another few thousand miles on it without issues. Wouldn't surprise me if he's trying to sell it because of the botched shift, to be honest.

nwGTS

One thing to note for folks is that these ranges are not cumulative of the range above it. That is, each range is isolated from any ignitions in another range.





So, for 997 Carreras it is possible to have more ignitions in range 4 than range 3 since range 4 covers 500 RPMs while ranges 3 covers only 200 RPMs.

This assumes the engine is slowing down linearly (it isn't).
This also assumes the DME does not count cumulative ignitions (R1:7300-7500, R2:7300-7700, R3:7300-7900, et al) even though the chart released by porsche isolates the RPMs in each range.

Hella-Buggin'

This doesn't make sense to me. The engines wind up and down the rpm ranges. How can it get to Range 4 without passing through range 3 on the way up or down?

talkenrain

Yes, thats how I felt when I got the results. Its an automatic (tiptronic) so it looks like a really bad down shift to second while in manual mode. It being so recent makes me want to run (not walk) away but with all the discussion here, I thought i'd get a few more opinions before dismissing it all together.