moxie (SF)

I know this topic has been covered a million times, so make it a million and one. I've come to the personal conclusion that DME reports are not very reliable, or at least overblown.

I bought my 997 Turbo 6spd a year ago, had them run a DME report as part of the PPI and it came back less than clean, it had a few range 5 & 6's. I had done my research and had bought into the DME hysteria and almost passed on the car (I'm glad I didn't). I finally got a durametric cable and read the DME report today, I was shocked to see some new range 5's, even a slew of range 4's. I know I did not have any miss down shifts, it's something you would remember, especially in these cars because your mind goes right to the DME and catastrophic failure, plus it's hard to make that sort of mistake, you have to really not be paying attention. I have never money shifted a car before and I don't plan to start now. I have hit the rev limiter plenty of times, it's easy to do in these cars while you're learning to drive them, and even after a year, I still do it from time to time (I'm used to my Z32TT, with it's 7,200rpm redline, I mostly shift by sound, and had to relearn what sounds this car needs to be shifted at).

My car has always been tuned, the car went straight from the dealer to have an aftermarket dealer package installed with exhaust, intake, headers & tune (which raised the rev limiter to 7k). Even with a rev limiter raised to 7k rpm, I'm not sure how a range 4 (7,400+ rpm) would register, let alone a range 5. My only conclusion is that the DME record system is not a very accurate and can record false readings. Even if the car is slow to the fuel cut off and the car does manage somehow go over the programmed redline and hit a range 4, I feel a lot less worried about ranged 4's if that's how they can be triggered, that's a very different scenario than a true missed downshift, that's a, whoops, bounced if off the redline, that's not going to cause any issues or damage.

This leads me to believe, for the range 5's and 6's on my car, maybe there wasn't a money shift like I thought there might have been when I initially bought the car. With the numbers so small for range 5 & 6, maybe it's just false readings, seems plausible now. I think the DME report just isn't very accurate, they don't seem to reflect real world driving. At least that's what my new readout suggests to me.

At the end of the day, I'm glad I didn't let a less than perfect DME report hold me back from my beautiful 997 Turbo 6spd, and you shouldn't either. These 6spd Turbos are phenomenal machines. 🤩

PV997

As much as I'd like to believe this I just don't think it's true. My 2010 TT with PDK has 60k miles and looks exactly like you would expect for a PDK car, with 70 range 1's and zero range 2 through range 6's. Pretty much every PDK car I've seen looks about the same. If the DME was prone to registering phantom high overrevs, why wouldn't they show up in PDK cars (or Tip cars)? Only other thing I can think of is that maybe something in the tune is causing false overrevs but I've never heard of that before. Unfortunately the simplest answer is usually the right one.

Edit: Just a thought that maybe adding the tune raised the rev limiter higher than it should have, or caused it to react more slowly. That could make the new overrevs real and seems more likely than them being phantoms. It also doesn't require a money shift which is awfully hard to forget if it happened.

snolvr

I on the other hand 100% agree with you. These DME reports are simply a tool, a snapshot of where the engine has spent a fraction of its life. Unfortunately, these DME reports DO get overblown, misinterpreted, and are the subject of whether or not otherwise good examples get passed up. Hell, I bought into the DME hysteria when shopping for my 997tt a few years ago, too. My DME report looks very similar to yours. Soooo happy I ultimately didn't let the internet determine that decision for me. Glad the DME police didn't let that affect your purchase either.

PV997

Completely agree that their significance is overblown, particularly if not recent. My contention is that if they are there in quantities more than a few oddballs (which could be caused by a data glitch), they are probably real.

550bryan

I have a completely stock 09 manual that has never been mis-shifted and yet I have registered a few 4, 5, & 6's. The numbers are a little mystifying as each unit represents one ignition so there are three ignitions per revolution, so that is 24,000 ignitions per minute at 8000 RPM. (I hope I have that right) It would seem impossible to register 5&6's in single digits as I have at that RPM. Wouldn't they have to come in bunches? As I have spent my life in the industry and have connections I was able to meet personally wit the PCNA technical specialist who offered to replace my computer implying it might fix my problem. It didn't, I still register an occasional 5 or 6 but again how can I register a single digit number with 24,000 of them happening every minute just doesn't make sense. After the fact the factory rep and I agreed it was a mistake t replace the computer. Here is an interesting line from his last e-mail to me,
"The unwritten rule when becoming a Porsche technician is to ”keep it below 1000” meaning to keep the engine 1000 rpm away from hitting redline so nothing it logged in the DME with manual AND PDK equipped vehicles. Yes, PDK will log these numbers as well (done it)." Seems like an admission that some random numbers can appear from simply hitting the rev limiter, which we have all done I suspect.

domkrz

I bought my car with 30,000kms with a few 5/6 overrevs in the millisecond range and didn’t think much of it.
Currently sitting at 170,000kms and I’m sure it’s registered more 1-6 overrevs in that time period.
My cars been tuned and I enjoy it all the way to 7200rpm as often as I can.
Long live the mezger engine!

saabin

Wait, so you got PCNA to replace your ECU due to "potentially faulty reading of DME overrevs in the ECU" ?

And they did replace it, and you still registered the occasionaly overrevs in Range 5 or 6 without ever miss-shifting your car?

Did I get that right?

550bryan

That's correct. I'm the only person who drives the car. I can assure you I know all about the "money shift" and it has never happened. I've been around for a long time and have owned at least a couple of manual trans car in my fleet at any point over my lifetime. I miss shifted a race car once and I can assure you know when you've done it. With everything I've learned I can only assume the car generates an occasional false reading. Doesn't happen all the time though. I went out in my car with the factory expert and purposefully hit the rev limiter hard (harder than I have even done before) and we downloaded the results, no additional overrevs were recored so it is sporadic. I guess it's all theoretical for me as I am not intending to sell right now. My 09 is a the ultimate spec so it would be highly marketable, but the DME BS does concern me a bit.

repcapale

I have heard this story so many times, but it just does not hold up. My 2010 manual DME is dead on accurate. I have owned it for 3 years and no “ghost” readings. The rev report is the same as the day I purchased it, plus a few extra range 1s.

Also, as someone else pointed out, where are the ghost readings in the PDK cars?

moxie (SF)

Have you bounced the car off the redline? I definitely have done that more times than I care to admit. The turbo is so fast and the redline is relatively low, it's an easy thing to do.

550bryan

Certainly not saying ever car does it regularly or ever. I'm not selling anything here so I have nothing to gain from misleading people and would sacrifice my reputation if I were less than truthful. I can assure you I have never mis-shifted my car, gone airborne or tracked the car. I have on occasion hit the rev limiter if first gear, which I assume has something to do with it. Although as I've said I hit it really hard when driving with the factory rep and it generated no over revs. Regarding PDK equipped cars, as you can see from the direct quote above from the PCNA technical specialist he has personally generated over revs in a PDK equipped car, which does raise questions about the accuracy of the data.

4ocious

DME reports are a tool Porsche uses to deny warranty coverage. Otherwise they are a meaningless POS report that should be totally disregarded unless the car has a proven history of neglect or abuse. If that's the case they are one of perhaps many future trouble red flags but certainly not the only one.

I've been a member of this board for many years and I have never read a report of any engine malfunction that can be directly traced and correlated with a DME report. Too much overhype from so-called "experts" who've read about DME reports on the internet (which is always true and factual) or elsewhere and because it fits their narrative they pass the information along without any objective proof or justification.

Sorry for the rant but this subject like a Whackamo comes up too often and needs to be beaten down every time until it eventually disappears.

550bryan

Unless you drive your manual turbo like the proverbial little old lady from Pasadena you will hit the rev limiter in first gear on occasion, as anyone who has driven one knows it happens really quickly in first gear. Of course that is what the rev limiter is for, to prevent over revs and to protect the engine. The rev limiter on a 997.1 is set at 6800 RPM, but the engine in other applications had much higher red line, it was 8500 RPM in the final GT2 street cat and even higher in racing applications. Has anyone seen a Mezger engine fail due to over revs? excluding race cars of course. Neither have I.

550bryan

Summed up nicely. Can't believe the posters on Bring a Trailer, the first comment from posters on any turbo or GT3 is, " they need to post the DME report". Here's the last paragraph from a recent Motor Sport magazine article on this amazing engine.
"What was so great about this engine? We loved its power, its torque delivery, its appetite for revs and fabulous sound. Porsche loved it for its strength. I once asked someone high up at Weissach why they were continuing with the Mezger engine when it meant Porsche had to build two entirely different flat six motors of near identical capacities. ‘We know everything there is to know about that engine, it’s a racing engine, it’s almost impossible to break. Why wouldn’t we use it? Which I guess tells you all you need to know about this engine and it’s genius creator too."
BTW 4ocious, are P car fleets look similar.

Robocop305

The more I read about these overrevs false recordings, the more I start to care less about them. I have actually seeing range 2 recorded on PDK cars.