DME report?

[jrider36]

I've come across "DME report" a few time here and in the 987 forum. Can anyone explain what a "DME report" is for a noob? I'm not sure if I had this done when I had my PPI for 09' non-s. Should I have this done before my factory warranty expires?

Thanks,

Justin

[thstone]

DME is the Digital Motor Electronics or ECU (Electronic Control Unit) that manages all aspects of engine control (ignition timing, fuel injection, oxygen sensor feedback, and numerous other functions). The DME can store faults that it detects and in some cases the DME will alert the owner of a serious fault by illuminating the Check Engine Light (CEL) on the dashboard.

A DME report is generated by using the proper test equipment to read out any engine faults that have been stored in the DME or ECU memory.

This is an important part of the pre-purchase inspection (PPI). Take a look at your PPI and it might have a section for engine faults or codes - that would be the DME report.

As long as your check engine light isn't on, then there really isn't any reason to check for engine problem codes unless you are curious or have some other reason to look into it.

[jrider36]

Thanks. To the point, got it...

[Flavor 987S]

A "DME Report" when part of a PPI is done to look into how the car was driven and possibly abused. A thorough and proper PPI includes a DME report, especially on later model Porsches.

Porsche also uses the DME report for warranty claims to determine, among several issues, if the engine has been over-reved, or 'chipped', just to name a couple.

In older Boxsters (986 and 996) the DME only captured 2 ranges of over-revs. Over revs in range 1 were considered "OK". While over-revs in range 2 were "bad" and pointed to the owner missing a down shift. You can get range 1 over-revs from hitting the rev-limiter in strong acceleration and shifting at or near redline. Range 2's occur on a missed down shift (and spins) since the rev-limiter does not work 'on the way down'.

In the 987/997 series Porsches, the DME started capturing 6 ranges of over revs. Range 1 and range 2 are "OK" and normal. I would suggest range 3 is not good. Range 4 is a bit of a gray area. And range 5 and 6 starts to mean Porsche will deny a warranty claim for abuse.

In the DME Report, a time stamp (in total engine hours) is noted when the most recent event occurred. This gives very valuable info, as well.

Another way a DME Report is part of a proper PPI is to somewhat validate the car's mileage. You can calculate the average MPH, and make a judgment if it is consistent with the car's history and condition. Also give indication if the car was mainly city or highway driven.

Here are some DME over-rev ranges:

[san rensho]

DME memory also has an over-rev report, so you can see if the PO over-revved the engine, usually by downshifting while already at high rpm's.

[Homeboy981]

The numbers in each of those Ranges represent "the number of ignitions" and NOT the number of occurrences. To make one revolution, in a 6 cylinder, it would take 6 ignitions.

When I first read the report, I thought it HAD HAPPENED that many times! So, take the number given, i.e., Range 1 & 2, and divide by 6 to determine how many revs were made in that Range.

Hopefully that will shed some light. My car had Range 2 overrevs, the bad kind, but knowing that it was ignitions instead of occurrences made me feel "somewhat" better.

[paulv]

Here's what you would see with Durametric -- over rev counts with total operating hours.




The Durametric site also has info on the relationship between operating hours and miles driven for used car buyers:

http://www.durametric.com/usedporschebuyersguide.aspx


Regards,

paul...

[jb92563]

Originally Posted by Homeboy981

The numbers in each of those Ranges represent "the number of ignitions" and NOT the number of occurrences. To make one revolution, in a 6 cylinder, it would take 6 ignitions.

When I first read the report, I thought it HAD HAPPENED that many times! So, take the number given, i.e., Range 1 & 2, and divide by 6 to determine how many revs were made in that Range.

Hopefully that will shed some light. My car had Range 2 overrevs, the bad kind, but knowing that it was ignitions instead of occurrences made me feel "somewhat" better.

The over revs are just an Indication of how the car was treated.

Its not like over revs on occasion are going to kill the engine.

The fuel cutoff usually takes car of it getting too far out of hand unless something stupid happened like your going 7200 rpm in 3rd and then shift hard and fast into 1st causing the engine to go over 9000 rpm.

Even then it will not likely kill it, but you are putting a lot of stress on the parts and increasing the chances of something failing.

I have learned that if you shift down 1 gear 2000 before redline you will never exceed redline and upshifts 1000 before redline are keeping you in the best part of power band.

Just my own observations with my 2001 Boxster S.