Discussion
I have seen quite a few mentions about Rev Zone 2 incidents on GT3's and it has got me thinking. I never checked this when I bought my Mk2 GT3 from my local OPC and I was wondering if these events are time stamped. I know I have never buzzed the engine on a down change, but can this be proven? The car was from an OPC with a full Porsche Warranty but it is a bit of a grey area, anyone add some clarity?
All this talk of bent GT3's, thrashed by the dealers and alike gets worrying. It has been on the ramp at JZM and they were impressed saying it was 100% genuine with no replacement bits and very tidy but one can't help thinking...
All this talk of bent GT3's, thrashed by the dealers and alike gets worrying. It has been on the ramp at JZM and they were impressed saying it was 100% genuine with no replacement bits and very tidy but one can't help thinking...
Any OPC or good independant will be able to download Rev Range one and two overrev information. My car was checked and reported as having plenty of RR one activity (electronic rev limiter and thus of no concern) and some RR two (mechanical overspeed) activity. I asked if the RR2 would invalidate any warranty claims, and was told it would not.
But then the same OPC told me my PCCBs were in serviceable condition, when clearly they weren't..........
If in doubt ask your OPC and get clarification in writing.
RR Two normally occurs when the driver misses a gear - usually, when accelerating hard and selects 1st or 3rd instead of 3rd or 5th. The limiter can't cope and this can lead to internal damage that may not reveal itself for some time. Shouldn't really occur on a GT3 though, where the gear selection is pretty precise.
If it results in an immediate failure, the damage and diagnostics would probably determine that it was caused by over-revving (driver error) and it would probably not be covered under warranty.
francisb said:
Geneve said:
RR Two normally occurs when the driver misses a gear - usually, when accelerating hard
i'd have thought it far more likely changing down too early under braking. i'd expect grabbing 3rd whist at the top in 4th is instant 6k+ bill not a nice little flag in the ecu...
Bouncing off the rev limiter (say whilst holding a gear for a corner) won't harm the engines internals (that after all is what the rev limiter is there for) However changing down from 6th to 5th (and getting 3rd by mistake) may definitely cause pistons to get "intimate" with the valves !!
I am aware of the cause of Rev Zone 2's and the difference with Rev Zone 1's, but I think the key question is are the events time and date stamped. I know I have not Rev Zone 2'd my car but if a previous owner has and this has caused damage (and I am not suggesting for a minute that this is the case!) how would I stand? I would not want to be held liable for damage I had not caused, which is the basis of my point I guess.
housemaster said:
I would not want to be held liable for damage I had not caused, which is the basis of my point I guess.
As I understand it you can go to OPC and get full print out of all of these ecu codes/events - it would seem a pretty pointless ecu feature if the log wasnt time stamped. The long and short of it is the OPC will have knownt this history when they sold it to you so its hard to see them wriggling out of a waranty claim on the back of pertinent information they withheld at sale time.
It's not just a matter of whether there's been a RR2 event, or how many. More important is what was the peak rpm reached.
The car is designed so that the clutch goes first, acting like a fuse, then at a higher speed bits of the top end begin to perish.
Even if you've had a fairly alarming over-rev, it may well have only affected the clutch, which could easily be (or already have been) replaced.
In answer to the original question I believe they are timestamped with the run time of the engine, and by taking the current run time you can get some idea of how long ago these ignitions happened - not terribly accurate for assessing who caused them, but if they had been 2 seconds before the engine expired you'd be pretty sure the OPC would name that as the cause. I also undertand there will be an entry for each ignition sequence, so a fairly short overrev would result in lots of entries.
If what I have read in the past is correct, what is logged (for each of range 1 and 2) is the number of sparks fired (in total) in the incident and the engine run time of the last incident in each range. So you will have range 1 - www ignitions at xxx hours and range 2 - yyy ignitions at zzz hours. The current engine run time from the ECU then gives you an indication of how long ago the last over-rev was. I don't believe it actually records a time stamp for each incident (though I am certainly not a Porsche tech 
).
Apparently you can read this yourself with any OBDII reader (think I heard that there is some open source software kicking around the net with build it yourself instructions for the interface if anyone fancies a bit of DIY).
). Apparently you can read this yourself with any OBDII reader (think I heard that there is some open source software kicking around the net with build it yourself instructions for the interface if anyone fancies a bit of DIY).
Greig and Colin are correct... the timestamp records number of 'ignitions' and at the number of hours this was last recorded. As Flemke has also said above - the engine could quite possibly have spent a long time time just inside the rev range 2 rev band or a very short time at significantly higher revs. TBH - if you are buying from an OPC, get a print out of the ECU at the time of purchase, keep it in your records and don't let it spoil your fun. There is far too much FUD (Fear / Uncertainty & Doubt) spread about rev range 2 and a lot of cars have at least a little rev range two logged without any issue.
HTH
Steve
HTH
Steve
OPCs aren't too keen on showing you the print outs if you're buying from them as i found out....to the point that they insisted it was policy.
I insisted in turn. They eventually showed it to me and it had way too many RR2 instances for my liking.
To my mind, its one of the few bits of objective factual information you can gather when buying a used car. I can't see the sense in not getting it, its a bit like doing a proper survey on a house before buying it.
cheers
Ajit.
I insisted in turn. They eventually showed it to me and it had way too many RR2 instances for my liking.
To my mind, its one of the few bits of objective factual information you can gather when buying a used car. I can't see the sense in not getting it, its a bit like doing a proper survey on a house before buying it.
cheers
Ajit.
flemke said:
It's not just a matter of whether there's been a RR2 event, or how many. More important is what was the peak rpm reached.
The car is designed so that the clutch goes first, acting like a fuse, then at a higher speed bits of the top end begin to perish.
Even if you've had a fairly alarming over-rev, it may well have only affected the clutch, which could easily be (or already have been) replaced.
I am not familiar with the road car but the 996 supercup car is designed to break the clutch on such occasions so if it is the same on the road car I would not have cause for concern.
singh911 said:
To my mind, its one of the few bits of objective factual information you can gather when buying a used car. I can't see the sense in not getting it, its a bit like doing a proper survey on a house before buying it.
cheers
Ajit.
Ajit - the point is that everyone has heard of rev range 2 but most have never been shown an official Porsche description of what it is therefore, how can everyone get overly worried by it? I was concerned when I bought mine from the OPC two years ago because everyone was over hyping it. The OPC didn't argue, gave me a copy of the report and a letter to say that existing rev range two logs would never be a problem.
Steve
Hey Steve
I think everyone should ask to see it and determine for themselves if they like what they read. A letter like the one you got provides appropriate cover if you decide that you'll go for the car after reading the report.
A lot of cars will have a little RR2 activity - and a little wouldnt bother me at all.
Its the ones with a hec of a lot of logs that one wants to avoid. Like the one i nearly brought......
Ajit.
I think everyone should ask to see it and determine for themselves if they like what they read. A letter like the one you got provides appropriate cover if you decide that you'll go for the car after reading the report.
A lot of cars will have a little RR2 activity - and a little wouldnt bother me at all.
Its the ones with a hec of a lot of logs that one wants to avoid. Like the one i nearly brought......
Ajit.
police state said:
Does anyone know if it is possible to diagnose a 993 for high/over revs?
No straightforward download method, but mechanical inspection of the end of the valve stems will reveal crescent shaped indentations which is normally a sure sign the engine has been over revved.
This causes the valve to bend slightly and stick open, thus allowing the end of the hydraulic tappet to "flip" over and present the end of the valve stem with a sharp edge (instead of the designed bearing face)
This sharp edge digs into the end of the valve stem creating the aforementioned crescent shaped witness marks.
I Am of dealer background and to be honest checking the car for RR2 is not asked at all you only check the error codes in the ecus and thats your lot as far as electrical ecu work goes....pretty poor thinkig about it.
Every car i check over for customers now im on my own gets a full inspection 1000000000000 point check !
I checked slippy diffs previous GT3 no RR2 ! most have a couple but not 1 ...damm impresive !
mike
sportsandclassic
Every car i check over for customers now im on my own gets a full inspection 1000000000000 point check !
I checked slippy diffs previous GT3 no RR2 ! most have a couple but not 1 ...damm impresive !
mike
sportsandclassic
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