I ask because I recently had a DME report run on my 997 Turbo, and the shop is telling me it shows over revs in Zone 5 "in the last 30 minutes of run time". I can see 31 ignitions in Zone 5.

The only one who's driven this car for months is me - and I *know* I didn't hit the redline, or miss a downshift. How can this be?? Can these reports be in error?

Thanks.

 

31 ignitions at redline is a blink...could have a lot of causes including a faulty sensor or the ecu itself...if you are sure you didn’t cause it and there weren’t any misfires and you have a relationship with your dealer talk to their master tech and ask him to explain the behavior...good luck

 

I've seen DME reports where a range 3 or 4 was a smaller number than range 5, which is impossible. I've also noticed mine sometimes tells me I've hit 1 or 2 recently when as far as I know I've been driving sedately and not running up to redline at all.

 

Thanks. And yeah, this is strange. I've attached the whole "tree". If I read this right, it makes it look like I abused the car (recently too!) - and I haven't.


Another question - I don't know where the sensor(s) for this data are - i.e., how the ECU determines that N ignitions took place in RPM range X. My car has a lightweight flywheel as a mod - I wonder if that could somehow skew the over rev data?

Thoughts? Thanks again.

 

Yeah, if you tried to sell that on BaT right now everyone would lose their minds about how you "thrashed" the car a few hours ago. I think ECU tunes and lightweight flywheels can definitely contribute to false readings.

 

False readings 100% occur, especially if you’re tuned.

 

In regards to selling, pay for a leak down and compression test...that should appease most potential buyers....as previously posted light weight flywheel and ecu tune can cause false readings.

 

I had the same issue with my car.
I knew i had not overreved the car, it was just as i bought it and drove 2000km home with the car i made a 111points test at porsche and they showed me the sheet.

I searched litle around internet and found some info about the sensor on the flywheel. The distance to the tooth is incorrect.
But havent checked it on my car.
The car was completely stock when that happend.

For me, i dont trust those sheets anymore because of that. Better to do a conditionstest on the car as someone mentioned.

 

Thank you everyone. Do any of you have a link to any source material that I could point the prospective buyer to? I realize at some point (real soon) this becomes an "it is what it is" situation, and both of us will have a decision to make; I'd just like to have as much information as possible to make mine.

 

A clean compression check and leak down test should indicate no bent valves or piston rods...usually what happens with over-revs...you can also have the cylinders scoped with a video camera. if all looks normal a potential buyer shouldn’t have a problem. Unfortunately, too many will not even look at a car with higher range over-revs.

 

I am probably missing something but did somebody at the shop drive it?

 

> Did someone at the shop drive it?

I explored that possibility, and am satisfied that it was not the shop - I really believe we're looking at an ECU software issue, possibly complicated by having mods such as the lightweight flywheel - especially if one of the sensor(s) involved reports data based on said flywheel.

 

Tuning does funny things.....never understood why porsche guys are so gunho on these reports. No other car that I've ever purchased does this come up or is even a point of conversation let alone contention.

 

"Yeah, I love the 997 Turbo for its racebred GT1 heritage and famous bulletproof Mezger engi-- wait, this car hit redline 3 times in its life? Pass."

 

I swear if I ever sell my car and someone asks me for a damn DME report, my car will certainly not be for them.