Engine over-rev – advice, please!

[muban11]

I am currently in dispute with Porsche. I noticed a rattling noise from the middle of 911s 2006. It turned out to be an issue with the gearbox. Porsche simply blame me for over-revving and will not cover it under warranty. The computer results shown below.the vehicle was over rev’s in following ranges:

n-max-Stored_2 - nnmax1 65535
n-max-Stored_2 - nnmax2 17276
n-max-Stored_2 - nnmax3 4299
n-max-Stored_2 - nnmax4 272
n-max-Stored_2 - nnmax5 1
n-max-Stored_2 - nnmax6 1
n-max-Stored_2 - tbtrnx1 1708.200 h
n-max-Stored_2 - tbtrnx2 1693.600 h
n-max-Stored_2 - tbtrnx3 1678.600 h
n-max-Stored_2 - tbtrnx4 1672.500 h
n-max-Stored_2 - tbtrnx5 1042.400 h
n-max-Stored_2 - tbtrnx6 1042.400 h


Do I have a case against Porsche?

[nsm3]

My guess would be no, if that range 4 recording is correct?

[Defcon5]

I assume 65535 is the mileage, rather than the peak revs reached

What exactly is wrong with the gearbox?

[thegoose]

Defcon5 said:

I assume 65535 is the mileage, rather than the peak revs reached

It's the number of ignitions in that rev range (divide by 3 to get the number of engine revolutions) - so for Range 1 it's 65,535 which is about 3.5 minutes on the rev limiter over the life of the car up to the last recorded incident, which was at 1708.2 hours - the info doesn't show total hours though.

The Range 5 and 6 figures of 1 each are clearly a glitch as it's impossible for them to have occurred in reality. If the Range 4 figure is correct it shows 0.72seconds (assuming 7500rpm, less if Range 4 speed is higher) which given that the engine has to accelerate to and decelerate from that speed within all of those 272ignitions/90revolutions means likely no more than 0.5second at the Range 4 engine speed.

I can't see how that could damage the gearbox in the slightest, unless the car is made incredibly poorly with no error margins in there at all, which it isn't. Of course, if you're a warranty company faced with finding an excuse not to pay a claim.....

[RatBoy M3CSL]

.. missing a downshift and buzzing the engine by going say 5th to 2nd by mistake would certainly spin up the gearbox pretty sharpish, it shouldn't cause any damage, but you never know, and that is why they are recorded for warranty issues, if you buzz the engine you loose the warranty, thats how it works..!

[Scott911]

If its been in range 4 then no as it has been over revved. In rare cases, Porsche will look at when it was over revved from the operating hours. If for instance, it was over revved at 109 hours and it's had 1600 hours run time, they sometimes they will offer goodwill or will allow a warranty claim! That's the case at our dealership anyway!

[Ian_UK1]

Defcon5 said:

I assume 65535 is the mileage, rather than the peak revs reached

What exactly is wrong with the gearbox?

The number recorded in the ECU is the total number of ignitions in that rpm band. But... the max number the ECU can store for any given rpm range is 65536 (2 to the power of 16). This means that this engine has been in this rpm band for AT LEAST 65536 ignitions or 21845 revolutions. At 7500rpm this is a minimum of about 3 minutes.