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Importance of PPI

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Old 07-15-2008, 09:09 PM
  #16  
Wellardmac
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Originally Posted by wross996tt
Sounds like you are indeed wrong...The "counts" are the number of ignitions. There are 3 ignitions per rev....so at 7000 rpm you get 350 ignitions/sec. 50000 counts would be 143 seconds in over-rev (type I) condition. 4988 would be 14 seconds...of type II....I would run still.
Just to put this into perspective... you could easily do this on one trip to the drag strip. It does not indicate an abused car (although other things that you said did indicate such), it just says that the car has been driven hard for just over 2 minutes in the course of it's life.

Gotta put things in perspective.
Old 07-15-2008, 09:31 PM
  #17  
Gaspasser19
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Originally Posted by joes c4 cab
Forgive my ignorance, but if the rev limiter cuts off fuel and spark, causing the revs to "bounce" down from the limit, how do you get a type 2 overrev? Just from going so fast into the limiter that it goes way over??
Type 2 overrevs come from a missed downshift, ie 5 to 2 instead of 5 to 4. I would imagine that it's not too hard to get that many ignitions from one or two missed downshifts if you think about it. True, it's potentially a bad thing, but I don't think it's a sure sign of "abuse". As for type 1 overrevs, I know I've hit the limiter on two separate occasions running out of 2nd gear while merging onto the highway. Totally benign situations in my opinion. I agree, the dry differential and neglected oil are another matter entirely.
Old 07-16-2008, 01:07 AM
  #18  
Van
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Originally Posted by MechanicalEng
the dealer called me back and they still want to sell me the car, the said $49k.. so 50.000 type 1 and 5000 type 2 are definitely a very large number?
There are enough of these cars out there, that you'll find one in the shape you want that will pass a PPI with flying colors.

Pass on this car and tell the dealer you're just not interested at any price.

I don't know if this car is a candidate for a CPO or aftermarket warranty, but if it is, the type 2 over-revs are the dealers' trump card... i.e. if the engine blows up, they'll point to the over-revs and say the engine was abused and it wasn't a manufacturing defect.
Old 07-16-2008, 02:25 AM
  #19  
blake
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Originally Posted by Van
I don't know if this car is a candidate for a CPO or aftermarket warranty, but if it is, the type 2 over-revs are the dealers' trump card... i.e. if the engine blows up, they'll point to the over-revs and say the engine was abused and it wasn't a manufacturing defect.
And that is the key... Many people that track their 911 exclusively dealt with this issue with the dealers when making a warranty claim in recent years. With the 997, I understand that they track 5 RPM levels (don't quote me) so as to help make *subjective* assessments regarding voiding the warranty. I'm sure there is a positive marketing spin for it, but I can't think of one offhand...

And regarding the question: Are Type IIs indicative of abuse? Clearly, I think it is abuse. Sending your engine to 12K RPMs due to a Type II Overrev is a serious problem. You might not blow the engine, but will weaken components... Of course, another check for abuse is looking at the maintenance history - fluid changes, major/minor services, etc. Lack of documentation is a warning sign...

My $0.02,
-Blake
Old 07-16-2008, 10:21 AM
  #20  
AOW162435
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Can you post the name of the dealer?


Andreas
Old 07-17-2008, 01:37 AM
  #21  
Nicolaasdb
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I am glad I bought a tip.....I don't think you can screw up or down shifting up with a tip.....can you??
Old 07-17-2008, 01:03 PM
  #22  
Tippy
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Originally Posted by Nicolaasdb
I am glad I bought a tip.....I don't think you can screw up or down shifting up with a tip.....can you??
No, but my 3rd was slipping a little more than normal and sometimes it would bang the rev limiter.
Old 07-17-2008, 03:23 PM
  #23  
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Run away from it ...as fast as you can
Old 07-17-2008, 04:25 PM
  #24  
omnipresent
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Originally Posted by MechanicalEng
the dealer called me back and they still want to sell me the car, the said $49k.. so 50.000 type 1 and 5000 type 2 are definitely a very large number?
If the PCar dealer said approx $20-25k in necessary repairs, why even consider a $49k offer?
Old 07-19-2008, 08:53 AM
  #25  
LJpete
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Glad you got the PPI. That could have been costly. Look at it this way, you potentially avoided a problem car.
Old 07-19-2008, 09:30 AM
  #26  
Chuck 951
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Don't know for sure but could be caused by a missed shift.

Very good idea on buying the code scanner and checking codes.

Chuck 951



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