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Hey guys (and gals). I am one of the lucky few that had bore scoring on my 03 996 with only 29k miles (after spending 3k to have LN IMS kit installed and doing the clutch). I bought it a year ago with 27k miles, had a PPI done (I guess not a good one) and still got scr*ewed.
With that said, I just put a deposit down on a 09 CPO Carrera S Cab.
Here is the DME from the dealer. Does this look okay??
Many thanks in advance as I am gun-shy given my last experience.
Looks good... Zero hits in ranges 4,5, and 6. Thats great! Out of curiosity... Any idea what the cause of the bore scoring was? Wondering if it has anything to do with hot/cold climates as Ive heard before.... Where are you located?
Thanks! I'm in CT, but only drove it 2k miles and in the warm weather.
I didn't want to spend any more money to find out. It jumped timing (engine light came on and I had it flat-bedded to dealer) - that was first issue, apparently (the dealer said, very rare). Tensioner was bad they said. I asked them how often they saw that, especially at 29k miles. They said never. Got worse...checked oil filter and found metal. Scoped the cylinders and one scored a little, one very scored. All options were bad at that point. Least bad option was get rid of the car.
Ok, so a Porsche friend just told me that since the car has operated 588 hours, or 35280 minutes. If the average rpm is 2500 that's 88,200,000 cycles or 530,000,000 cylinder fires. So if we divide 20,173 misfires by 530,000,000 cylinder fires that's .004% of the time is misfires. Wow, that was a lot of math...
If this math is correct, it's misfiring .004% of the time. I wonder if that's good??? I hope so!
The math for the misfires wouldn't necessarily be like that. Typically with misfires things are fine with the car, a part fails like a coil pack or a crank sensor, then misfires appear in a very short period of time. So the math is more like 20K misfires (ignitions) / 4 (4 stroke engine) = 5000K total revolutions. At 2500 rpm that's two minutes of total misfires if every cylinder misfired at the same time. More likely it's one cylinder with a cracked coil, so multiply by 6 to get 12 minutes total. If it was intermittent it would be over a longer period of running but still clumped together over a short period of time. Even being conservative and saying the owner let the check engine light stay lit for upwards of 10 driving hours, then the car had zero misfires for 98.3% of the time, then misfires present for 1.7% of the time.
I wouldn't worry about the misfire count right away. If the service history shows coil packs replaced or a crank sensor then there's the story. Also check the DME for error codes. If it shows misfires present then the CPO process would have to fix that. In my book the previous misfires count should not be an issue on this car especially since it's CPO'd. But make it clear during the purchase process that it needs to be checked out. Ant the top of the screen shows zero misfires on cylinders 2-6 in the past ten trips (cylinder 1 is not shown).
Is this car a manual transmission? If yes the overrev report is gorgeous. If it's an automatic than it's a typical report.
For reference the automatic transmission does not go beyond the rev limiter. It can bounce off of it for counts in range 1 under some circumstances, maybe range 2 in rare instances. Although I'm not an expert I have yet to see any automatics with counts in range 3 and higher except for glitch counts. The report you posted looks like an automatic transmission - low counts in range 1, zero counts everywhere else.
With manuals a bad downshift will shoot the engine RPM up too fast, well past the rev limiter even as the DME cuts the fuel supply - it's all about gearing and flywheel momentum. This causes counts to show up in ranges 2 and higher depending upon how severe the event was. So manuals typically have an exponentially decaying number of counts - range 1 the highest, range 2 perhaps 10X less, then single digits in range 3 or maybe range 4 if any. Tracked cars will have a huge number in range 1, perhaps maxed out a 65535. Not a problem as the engine is designed to run in this range but it does scare some buyers. It's all about the counts in the higher ranges and how recently it occurred though. Abused engines often have recent events in ranges 4+ (tire kickers out joyriding?), or high counts in range 4+ (inexperienced MT driver misshifting often), or scary numbers in range 5 and range 6 (some idiot trying to do a burnout improperly?). The thing to look out for is high range events that are recent or lots of high range events regardless of how recent it occurred.
I am one of the lucky few that had bore scoring on my 03 996 with only 29k miles (after spending 3k to have LN IMS kit installed and doing the clutch). I bought it a year ago with 27k miles, had a PPI done (I guess not a good one) and still got scr*ewed.
Same boat, however my scoring didn't make itself known until I'd driven the car 6 years and put over 30K on it. And even then, it was only apparent when the engine was apart. Scoring had begun on the piston skirts, not yet progressed to the bores. A borescope showed nothing, so a PPI wouldn't have picked it up.
I decided to get a bulletproof RND engine with Nickies and IMS Solution, rather than trade up to a similarly-equipped .2 as the newer car would eventually depreciate the same amount the engine cost me in mine. Basically I was lazy to go through the hassle of selling mine and hunting for an '09 with the right color and options I want. Had my car been a 996 I probably would have taken the other path.
09-08-2016, 09:19 PM
Upgrading from 996 to 997.2 - DME help
