advice sought: over-revving in 997.1 Turbo - Page 4 - 911/Carrera GT - PistonHeads UK

Hi All I'm in the process of viewing a 997.1 Turbo and have just had an independent PPI carried out. Most of the findings are straightforward 'cost to replace' items, so nothing scary. However, there is evidence of over-revving as follows: - Range 4 x 7 at 608.6 hrs - Range 5 x 2 at 608.6 hrs - Range 6 x 1 at 606.7 hrs The car is now at roughly 630 hrs. Other than the above findings, the car is pretty immaculate. So I have two questions: 1. What is the 'worst case scenario' if the over-revving goes bad? I presume it's a replacement enginge? 2. What would PH-ers do in my position - buy or walk away? Any and all advice greatly appreciated. Many thanks, Stuart

I had a turbo with Range 4: 3 ignition Range 5: 2 ignition Range 6: 1 ignition If you do the math that's just a fraction of a ms. Still have OPC or independent to a full check on it.

Too recent for me. I'd look elsewhere.

While i think that there is too much of this over rev nonsense with Porsche's compared to any other car you buy, that looks like a major mis shift not that long ago, bearing in mind thay made thousands of 997 turbos you wont struggle to find another one that has not been buzzed into range 6. walk away and find another one.

Thanks all so far. So one 'buy' and two 'walk away' opinions so far. Can I just check: can even just one single rev into range 6 be enough to cause fatal engine failure (in theory)? And also, I'm just waiting to confirm the current total operating hours. If this was at 730 rather than 630 (which it might be), would that change anyone's opinion? Thanks again!

stumcnu said: Hi All I'm in the process of viewing a 997.1 Turbo and have just had an independent PPI carried out. Most of the findings are straightforward 'cost to replace' items, so nothing scary. However, there is evidence of over-revving as follows: - Range 4 x 7 at 608.6 hrs - Range 5 x 2 at 608.6 hrs - Range 6 x 1 at 606.7 hrs The car is now at roughly 630 hrs. Other than the above findings, the car is pretty immaculate. So I have two questions: 1. What is the 'worst case scenario' if the over-revving goes bad? I presume it's a replacement enginge? 2. What would PH-ers do in my position - buy or walk away? Any and all advice greatly appreciated. Many thanks, Stuart I have nothing to add about rev ranges but ... those look to me like the previous owners last hoon.

Run Forest run. I walked away from a GT2 recently which had RR 5. Find a car without the dreaded over revs if you can or with no ore than RR3 http://www.pistonheads.com/gassing/topic.asp?h=0&a...

What the choc sex man sed. Looks like a final hoon to me. Rev range 6 = run away.

I would suggest that the numbers are wrong, there's no way you could get 1 rev in range 6 and 2 in range 5.

It's impossible for those recorded 'over-rev' stats to be correct! 2 reasons: 1) It would simply be impossible for an engine to accelerate all the way through RR5 to RR6 and back again in 1 ignition either way - or 1/3rd of one rotation of the crank. At say 7500 rpm (just guessing the RR5 rpms, so don't shoot me down in flames) that's .00266 of a second. .00266 of a second, each way, to accelerate then decelerate all that rotational mass by 1000 rpm is not going to happen. 2) The above's irrelevant anyway. There are only 2 RR5 ignitions recorded in total. Notwithstanding the rotational acceleration that breaks the laws of physics, one of those ignitions would have had to have happened as the crank accelerated into in RR6 and (at least) one more would have happened on the way down again at 606.7 hours. That being the case, how the hell can the RR5 recorded at 608.6 hours have happened? There must have already been 2 recorded by that time from the previous 'over-rev' (and in reality a lot more, had a real over-rev happened that didn't break the laws of physics). So the 608.6 time stamp HAS to be false. What you're looking at here's a glitch in the over-rev recording algorithm in the ECU. Wouldn't be the first time, won't be the last. Edited by Ian_UK1 on Tuesday 24th June 15:43

Agree with Ian, as ever a little knowledge is a dangerous thing...

Eek - some interesting information to work through here. I understand only the basics of this RR stuff, but isn't another theory that: - The RR6 was a 'change down' over-rev = (+1 RR6) - On the way back down from the RR6 overrev it clocked at RR5 = (+1 RR5) - Then there was a separate 'change down' over-rev in RR5 (i.e. one that was between 7,900 and 9,000 so not enough to buzz into RR6) = (+1 RR5) - Therefore 2 in RR5 and 1 in RR6? Or have I got totally the wrong end of the stick?! What would people do - get another ECU read-out elsewhere? Cheers

It's impossible to achieve those numbers as the engine can't spin that fast to achieve them.

^^^ Whether it's a mistake/glitch is sadly irrelevant. They're on the ECU now, and short of major software surgery they ain't going anywhere. When you come to sell it many dealers won't touch it, and private buyers doing checks such as you have are likely to walk away. Unless it's a serious bargain and you're up for the potential dramas, then there are plenty of other, lower hassle options, to choose from.

stumcnu said: Eek - some interesting information to work through here. I understand only the basics of this RR stuff, but isn't another theory that: - The RR6 was a 'change down' over-rev = (+1 RR6) - On the way back down from the RR6 overrev it clocked at RR5 = (+1 RR5) - Then there was a separate 'change down' over-rev in RR5 (i.e. one that was between 7,900 and 9,000 so not enough to buzz into RR6) = (+1 RR5) - Therefore 2 in RR5 and 1 in RR6? Or have I got totally the wrong end of the stick?! What would people do - get another ECU read-out elsewhere? Cheers The numbers in each rev range represent the total number of ignitions (3 per revolution of the engine) that took place whilst the engine was in a particular speed range - not the number of times the engine was in that speed range. Being a total, they are also cumulative.

Junior Bianno said: ^^^ Whether it's a mistake/glitch is sadly irrelevant. They're on the ECU now, and short of major software surgery they ain't going anywhere. When you come to sell it many dealers won't touch it, and private buyers doing checks such as you have are likely to walk away. Unless it's a serious bargain and you're up for the potential dramas, then there are plenty of other, lower hassle options, to choose from. Exactly what I was thinking ..... You , the seller , trying to convince the next bloke thats its all ok. Or at the very least having this whole confusing and ambiguous conversation. Those numbers do look like a final trackday or similar. If the ECU has incorrectly interpretted the over rev , will a main dealer be able to understand this fact and replace the ECU or wipe it clean ???

I think this is so stupid. I understand what people are saying about it but it's just so stupid that people have to take this into account. Only a history of constant ragging would put me off buying. Not one instance of the car being over revved. Do other car companies even have this facility? How is this information gathered, what software?

Isysman said: I think this is so stupid. I understand what people are saying about it but it's just so stupid that people have to take this into account. Only a history of constant ragging would put me off buying. Not one instance of the car being over revved. Do other car companies even have this facility? How is this information gathered, what software? Not only is it 1 incident, it's also about 1/100 th of a second in RR 4. What would be interesting is what the over revs in 1 and 2 are, which should give a better indication of how the car has been driven. And also the average MPH.

Those numbers wouldn't concern me in the slightest. The figures for the lower rev ranges will give a better indication as to how it's been drive .

To answer the question about RR1 to 3: RR1: 2,032 @ 608.8 hr RR2: 436 @ 608.8 hr RR3: 67 @ 608.6 hr Just to say - I'm now totally confused about the advice being offered! It ranges from "run like the wind" to "don't worry about it"... Any final thoughts? I need to make a final call by 0900 tomorrow...! Stuart

Found this online. Are for me to fully understand but interesting nonetheless. http://www.911virgin.com/porsche/rev-range-informa...

Always dangerous taking a small proportion of an article , but this seems the most relevant bit to me "We are regularly approached to help interpret Rev Range Data. The ability to separate genuine incident from an erroneous recording is critical. In general terms we would consider the registering of less than 10 ignitions within a given range to be no cause for concern. 10 ignitions represents fractions of a second, insufficient time, in our experience to cause damage. Porsche take a different view and consider the registering of a single ignition (one third of an engine revolution) to be relevant. A single ignition recorded in rev range 3 or higher within a 200 operating hour period means that an engine compression test is deemed necessary. The registering and recording of a single ignition at such high engine speed, in our view, is just not possible in the same way that a single ignition in, for example, Rev Range 4 can't follow a single ignition in the previous rev range. In order to pass in to a higher bracket of engine speed the engine must complete at least a full engine revolution, a minimum of 3 ignitions." Thoughts?

stumcnu said: To answer the question about RR1 to 3: RR1: 2,032 @ 608.8 hr RR2: 436 @ 608.8 hr RR3: 67 @ 608.6 hr Just to say - I'm now totally confused about the advice being offered! It ranges from "run like the wind" to "don't worry about it"... Any final thoughts? I need to make a final call by 0900 tomorrow...! Stuart What's the mileage? Work our the average mph. Should be about 40. The RRs don't look that bad. You won't get a Porsche warranty without further miles and checks, so if that's important, walk. If it's not, and the price is right, I wouldn't worry too much. Most turbos will have activity in 1 and 2. It's unfortunate about the 3-5 activity, but it looks like it was a single, very short incident.

Mileage is just under 21k - so average mph of 33. And in every other respect the car is in mint condition. I'm sensing a swing back towards buy in the opinions here and I have to day that the logical interpretation of the data seems to agree with this. I'm just pretty nervous about the "WALK AWAY!!" messages!

I think the "walk away messages" are based on the "stigma" of the readings as opposed to hard facts that the engine will blow up. That seems to be Virgin 911's view as well. The next buyer may well want to know the RR position and have the same thought processes as you. Hopefully by then it'll have done more miles since the RR 5 incident without blowing up! Average MPH looks good.

stumcnu said: Mileage is just under 21k - so average mph of 33. And in every other respect the car is in mint condition. I'm sensing a swing back towards buy in the opinions here and I have to day that the logical interpretation of the data seems to agree with this. I'm just pretty nervous about the "WALK AWAY!!" messages! Just remember the "buy" recommendations aren't from people that are going are going to be stumping up their hard earned cash. You are! There's very likely nothing wrong with the car, but the hard facts are that an OPC and most reputable independents wouldn't buy that car to resell. It WILL be an issue when you come to move it on. I've been at the wrong end of ECU issue with a 997 Turbo and it was a painful experience.

Hi All Many thanks for the advice and opinions offered so far - I really do appreciate the time people have taken to respond. Just to close this thread off, I thought I'd let you know that I've decided not to proceed with the purchase. Whilst I can convince myself logically that it's highly unlikely there would be an engine problem given only one ignition in RR6 and 2 each in RR4 and RR5, the two key points for me are: 1. The vehicle wouldn't get a warranty 2. I don't want the risk of having this challenge myself when I come to sell in the future On top of this my suspicion is that many of the specialists probably wouldn't buy and sell a car with these RR readings - although this is obviously up for debate. Thanks again for the advice. Stuart

stumcnu said: Hi All Many thanks for the advice and opinions offered so far - I really do appreciate the time people have taken to respond. Just to close this thread off, I thought I'd let you know that I've decided not to proceed with the purchase. Whilst I can convince myself logically that it's highly unlikely there would be an engine problem given only one ignition in RR6 and 2 each in RR4 and RR5, the two key points for me are: 1. The vehicle wouldn't get a warranty 2. I don't want the risk of having this challenge myself when I come to sell in the future On top of this my suspicion is that many of the specialists probably wouldn't buy and sell a car with these RR readings - although this is obviously up for debate. Thanks again for the advice. Stuart good decision. A nice car will turn up.

Porsche rev range datalogging causing more problems than it solves, volume 627.

To be fair, it's the hype and misinformation surrounding the data rather than the data itself.

Especially when you consider the probability (if I'm reading it correctly) that the RR data is an erroneous reading.

All good points - however, erroneous or not (and it's impossible to prove as I understand it) the fact is that it wouldn't get a warranty, and I'd have the same issue when I came to sell in future (albeit there would be greater operating hours). But I do recognise this is a marginal (and very personal) call!

stumcnu said: Mileage is just under 21k - so average mph of 33. I had mine inspected by 9E and they said 30 is average, mine was less but has spent its life in London. Also has 1 range 4 but no 5 or 6, which they also said was nothing to worry about. Now that you have decided not to go ahead, can you post a link to the car

It is possible to prove on the basis that it's impossible to generate that data. Even Porsche can't bend the laws of physics.

Im pretty sure that its erroneous data but heres 3 things to consider. 1. A new Mezger engine is circa 40k 2. There are other cars available. 3. Porsche will not warrant it.

mollytherocker said: Im pretty sure that its erroneous data but heres 3 things to consider. 1. A new Mezger engine is circa 40k 2. There are other cars available. 3. Porsche will not warrant it. This. Plenty around, why take the chance? Even if it's a tech glitch you will get touched up come sale time...

Thanks all - that's my thinking too. In response to the request to post the link to the car, I'd prefer not to - that feels pretty unfair to the person trying to sell it I suspect. Hope people understand.

Adam B said: I had mine inspected by 9E and they said 30 is average, mine was less but has spent its life in London. Also has 1 range 4 but no 5 or 6, which they also said was nothing to worry about. Now that you have decided not to go ahead, can you post a link to the car you cannot quote 30mph as average, I did that once and got shouted out the forum !!! :-)

Agreed with Ian, my RR had a reading of 1 in RR4, RR5 and RR6 which is obviously impossible. Even the OPC 111 point check confirm it was erroneous data.

As others have said, this is such a load of tosh...especially for the GT/Turbo/Mezger engines (I don't read about the cooking cars). I have as yet to meet someone or read a forum where someone's mezger engine blew up because of this. ...it was a system Porsche brought in to put limits around their warranty liability. Relevant if you want to warranty a car. Once out of warranty or you tend to modify (e.g. most GT3s with aftermarket brakes, exhausts, etc) it becomes almost irrelevant - ok, its gives an indication of how the car was driven and I might be concerned if the car had very major activity in the highest band. I think there needs to be a mindshift change where this data is mainly for warranty applications and not for safety reasons. I suspect for 996 cars, most are no longer in warranty and therefore overrev data is irrelevant (apart from major activity). Other manufacturers do not even bother logging this

LaSource said: As others have said, this is such a load of tosh...especially for the GT/Turbo/Mezger engines (I don't read about the cooking cars). I have as yet to meet someone or read a forum where someone's mezger engine blew up because of this. ...it was a system Porsche brought in to put limits around their warranty liability. Relevant if you want to warranty a car. Once out of warranty or you tend to modify (e.g. most GT3s with aftermarket brakes, exhausts, etc) it becomes almost irrelevant - ok, its gives an indication of how the car was driven and I might be concerned if the car had very major activity in the highest band. I think there needs to be a mindshift change where this data is mainly for warranty applications and not for safety reasons. I suspect for 996 cars, most are no longer in warranty and therefore overrev data is irrelevant (apart from major activity). Other manufacturers do not even bother logging this Someone on here had a 996TT go bang, ended up getting a new engine after a massive battle with Porsche.

If you're refering to IMI A, I think it was a 997.1, and specifically the reason Porsche (initially) declined the warranty claim was over revs.

I think this thread has put me off buying a Porsche for good now. I know, nobody really cares about what i think, which is absolutly fine and totally understandable, but with all the comments about overrevs being the deathknell for motors and should i buy, shouldn't I buy, I'd be too worried that i'd inavertantly caused an overev and would be stuck with a seemingly worthless car.

FeelingLucky said: If you're refering to IMI A, I think it was a 997.1, and specifically the reason Porsche (initially) declined the warranty claim was over revs. That's him.

RGambo said: I think this thread has put me off buying a Porsche for good now. I know, nobody really cares about what i think, which is absolutly fine and totally understandable, but with all the comments about overrevs being the deathknell for motors and should i buy, shouldn't I buy, I'd be too worried that i'd inavertantly caused an overev and would be stuck with a seemingly worthless car. Only for those that don't understand the data and want a PCUK warranty. It wouldn't put me off, I'd go as so far to say I'd use it as a bargaining point as the next purchaser would to me.

RGambo said: I think this thread has put me off buying a Porsche for good now. I know, nobody really cares about what i think, which is absolutly fine and totally understandable, but with all the comments about overrevs being the deathknell for motors and should i buy, shouldn't I buy, I'd be too worried that i'd inavertantly caused an overev and would be stuck with a seemingly worthless car. buy a PDK car then

mrdemon said: buy a PDK car then This is advice I'd have agreed with until I read the 911 Virgin page about over-revs (linked-to earlier in the thread). They're now saying it's possible to over-rev Tip/PDK cars too.

RGambo said: I think this thread has put me off buying a Porsche for good now. I know, nobody really cares about what i think, which is absolutly fine and totally understandable, but with all the comments about overrevs being the deathknell for motors and should i buy, shouldn't I buy, I'd be too worried that i'd inavertantly caused an overev and would be stuck with a seemingly worthless car. Quite - this really has all reached silly proportions. Even worse - the ECUs in most Porsche cars are capable of generating & recording false over rev stats (and regularly do). Whilst it's usually possible to spot erroneous over-rev data - the car that's the subject of this thread being a perfect example - the hype and general lack of understanding around the subject, together with Porsche's 'no warranty' stance, can potentially leave you with a 'worthless' car that has never even been over-revved. Scandalous! Afterthought: if the ECUs can record over-rev stats that never happened, I wonder if they can ignore real ones that did, leaving potential purchasers buying a disaster waiting to happen? Afterthought 2: anecdotal evidence would suggest it's a 10-minute job to zero-out the over-rev counters with the right chip reader/writer if you know how to use one. Given the potentially detrimental effect on a cars value of adverse over-rev stats - largely caused by Porsche's attitude - the temptation to 'get rid of the problem' prior to putting the car in for service / warranty-renewal must be immense. Edited by Ian_UK1 on Thursday 26th June 10:08

Very interesting read here. http://www.911virgin.com/porsche/rev-range-informa...

Porsche has created an industry out of RR data. No one has any clue what the RR data is for a 993 or 964, and no one has ever been put off buying one due to the lack of data. It's good as a comparative tool as opposed to a definitive tool for whether an engine is going to blow. I imagine the vast majority of 993 and 964s (and cars from other manufacturers) would be unsellable if we had the same date for them.

Soov535 said: That's him. This doesn't make it 'the rule'. That sounds more like the exception to the rule. To suggest that having data like the OP posted here and ignoring means your engine will go bang is propostouros. If it showed habitual over revving over long periods then I would be dubeous about buying. I never even looked at this data when I bought my car. I looked at its service history, mileage, and spoke to the OPC at length about any work carried out etc. all the traditional stuff. The first thing I would do would be to show the data to an OPC and ask them to state if they can see it's erroneous data and if they would still issue a warranty after their own investigations. If they say no, then I'd understand why the OP would pass on it. It still makes me mad that Porsche have created this nonsense.

mrdemon said: you cannot quote 30mph as average, I did that once and got shouted out the forum !!! :-) No you didn't. I quoted 38mph as of my own 2 cars and you called bulls t and demanded proof. You're obviously as good at remembering things as you are at your punctuation and capital letters. Re rev ranges - Soooo boring. Worst case scenario is it breaks, you fix it and live happily ever after. Also the £40k quoted for a new Mezger is a Porsche motor. Most people will rebuild they're matching numbers motor for £10-£12k if nothing has destroyed the cases. Edited by marky911 on Thursday 26th June 13:16

Also, as has been touched on above, how many air cooled cars would have rev range over rev data and also how many air cooled cars have had engine rebuilds anyway. I don't understand the intense fear of a rebuild by water cooled owners given the costs of the cars involved. Edited by marky911 on Thursday 26th June 13:20

marky911 said: I don't understand the intense fear of a rebuild by water cooled owners given the costs of the cars involved. I think the issue has been driven by Porsche & the underwriters who determine the criteria under which they'll sell their 3rd party insurance.

Yep well there is that side of it. I've fortunately never had a car with OPC "clown restrictions" warranty, so I've always been on my own as far as running the car goes. Best way for me.

marky911 said: Yep well there is that side of it. I've fortunately never had a car with OPC "clown restrictions" warranty, so I've always been on my own as far as running the car goes. Best way for me. Agreed. The warranty is a hindrance and not a help on the older (simpler) cars. You cannot modify with improved parts and you end up having to use the more expensive and (usually) less experienced OPC shops. On a 996 GT3 for example there is very little that requires warranty use. In 6 years of running 4x 996 GT3/RS cars over that period I have NEVER needed once a claim that would have been honored under a warranty - that is something like £10,000+ of warranty cost savings! ...and no one buys a new engine even if there is an issue. I appreciate that a sporty Porsche can be a scary purchase...but no more risk than any other brand - in fact I would say less risk.

So, what is the usual range of mph figures calculated from operating hours?

lingus75 said: So, what is the usual range of mph figures calculated from operating hours? This obviously depends on how the car has been used but 40 ish seems to the average I have seen.

lingus75 said: So, what is the usual range of mph figures calculated from operating hours? 30 like the Indy said :-) I picked up my car ar 27mph ave. Now it gets used only on fast roads and big hoons, ave is now 33mph after 10k miles. Very hard to get to 40mph unless you live on the motorway or drive at 40mph over the limit every where. When I was a field eng I ave 30mph over 40k miles per year year on year driving a lot of motorway. Very hard to make up time due to stopping at lights to get any higer. All these rev rage reads outs posted are always around the 30mph mark, people who state much higher figures never post their data, funny that, :-)

Think more like 15 for a city based car

stumcnu said: Thanks all - that's my thinking too. In response to the request to post the link to the car, I'd prefer not to - that feels pretty unfair to the person trying to sell it I suspect. Hope people understand. Very fair (it was my request), I was interested as it might be a nice car, not in it getting known as a bad car, but the latter might well happen

marky911 said: Also, as has been touched on above, how many air cooled cars would have rev range over rev data and also how many air cooled cars have had engine rebuilds anyway. I don't understand the intense fear of a rebuild by water cooled owners given the costs of the cars involved. Edited by marky911 on Thursday 26th June 13:20 I am sure that many air cooled engines have been over revved, but they are mostly very strong units which will endure a lot of punishment, although they will stretch their chains given a significant over rev. Just because there is no data, it doesn't mean you can't make checks, and of course you should! I would imagine that most manufacturers now have rev range data recorded, amongst lots of other data, but only bring it out if there is a warranty claim. I think its a good thing. I would rather know than be in the dark. How you use the data is another thing entirely.