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Over-Rev History

Description:

The Cayman's DME (Digital Motor Electronics) records the number of ignition cycles that occur when the engine speed passes 7,300 RPMs. It also records the 'hour' of operation in which the incident took place. These records can be retrieved by using a PIWIS or Durametric Diagnostic Cable. The information can be used by a Porsche dealer to deny a warranty claim when abuse is the cause, or by a potential buyer to identify abuse of a used Cayman.

There are six ranges of over-revving that are logged by the DME:

Range	Engine Speed	Comments
1	7,300 - 7,499 RPM	Ranges 1 and 2 can be achieved by bumping the rev limiter (more likely if a car driven in Sport Chrono sport mode). Most dealerships will accept ignition cycles here without denying a warranty claim.
2	7,500 - 7,699 RPM
3	7,700 - 7,899 RPM	This ranges (and beyond) can only be achieved by something mechanically forcing the engine to this speed, like a miss-downshift. These speeds are pushing the range of physical damage and may result in warranty denial.
4	7,900 - 8,399 RPM	With cycles in this range, it is very likely that the engine has been damaged and will likely suffer a premature death. Budget for a new engine. This range is considered abuse, so warranty coverage is very unlikely.
5	8,400 - 9,499 RPM	An M97 engine will be severely damaged by these engine speeds and will likely have failed as a result. A 9A1 engine is more likely to survive this range but not without damage.
6	9,500 - 11,000 RPM	There is almost no chance that this engine is running. The Cayman engines are likely to spin bearings and eat valves at far lower speeds than this.

Don't be alarmed if you see 1,000 or more cycles in a range. That sounds like a lot, but keep in mind that a Cayman engine sees 3 ignition cycles per revolution. You can determine how much time was spent in the range by using the following formula: Time at Over Rev = Ignition Cycles / (RPM/20) . So, 1,000 cycles would be less than 3 seconds, or more likely, three 1 second bumps into the rev limiter.

It is possible to use aftermarket software to erase over-rev records, so this test should not be used as a definitive or exclusive identifier of abuse. If buying a used Cayman, a pre purchase inspection conducted by an experienced Porsche repair shop or dealership is a very good idea.

FAQ Information:

This FAQ was written by Gator Bite.
Last Revised: April 2012

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