Fullyield

Greg, I think n4life’s comment as to why the computer does not flag injector issues is spot on. The computer is looking for misfires or lack of fuel pressure, not altered spray patterns that do not cause misfires. Plus, a leak down issue while engine is off would not be detected because the engine is off so the computer is not collecting data. The best way to monitor injector/fuel dilution issues is with regular and consistent used oil analysis so you can immediately address it should it occur.

IXLR8

Either this is a real problem where all cars are being affected which is not the case, or it is a possible owner issue or a used car purchase where you had no idea how it was previously driven and/or maintained. And if it is not the latter, "fix the damn issue in design and change the process".

We had a guy at work and he would start up his engine in the dead of winter (well below 0F) in the parking lot and race to the street only to have to stop before the oil got to everything. No wonder his relatively new car needed a new engine which Honda replaced under warranty.

Then we have a PCA member who had bore scoring. OK, so the car was bought used, but that was years before the bore scoring started. Of course he bragged that he ran 100% of the power 100% of the time. Yeah right, maybe on the Nardo test track, but you get the idea. Who knows why he experienced bore scoring.

I have another PCA friend who has over 100,000 miles on his 997.1. No issues, but then he is not driving the pi$$ out of it, and certainly not after start up. I personally drive my cars gently for at least 10 miles before taking up the revs.

silver_tt

There is no question this is a real problem. So many variables at play here that it would be hard to distill it down to a simple answer. I have seen engines with very, very low mileage that suffered from bore scoring.

Pound for pound, IMHO a port injected Mezger is still the best technology you can buy for a modern racing engine in this class. It is effectively bulletproof with no true Achilles heel (coolant lines maybe but that's about it). You can bang on that thing all weekend long at a track event and it doesn't even flinch.

IXLR8

Possibly. Per 100,000 vehicles sold, how many engines were replaced within warranty or "good will" and how many were replaced by owners thereafter? Impossible to answer.

Just remembered, another 997 friend of mine had his engine replaced by Porsche shortly after taking ownership of it at the Porsche dealer where he bought it used. He later found out the original owner who had leased the vehicle when he had bought it new had a son who abused it. Personally, I would never buy a leased or rental vehicle.

silver_tt

The only way for your friend to have possibly known would have been to do an invasive PPI before taking delivery and even then it's still not 100%. You can look at over revs and things of that nature but I personally wouldn't even touch a car unless I could get access for a scope into ALL of the cylinders and drop the sump at minimum. Doubt most people or dealers are going to want to do that for a prospective buyer... especially in a market like this which is completely insane. But without doing that as a buyer, you're effectively playing Russian roulette.

IXLR8

In his case, bought from a Porsche dealer and the car was CPO'd.

pkalhan

After reading this thread....991.2 or newer for me!

BlueShell

There's not enough data to even remotely be statistical significant. If you're going to write off an entire generation based on this thread, you're probably gonna write off the 991.2 as well when you encounter the other threads.

Fullyield

Well, see Charles Navarro’s excellent discussion above re: SUMEbore cylinder walls as compared to Alusil and Lokasil technologies. The fuel injectors have changed also….at least in the 992 version of the 92A EVO engine….so Charles’ injector discussion is equally relevant. The tight piston to sleeve clearance that Charles discusses could also be an issue unique to the 991.1. So, pkalhan’s conclusion to prefer a 991.2 engine is not baseless regardless of statistical significance. If it is your 991.1 engine destroyed because of bore scoring (like the numerous examples discussed above by several different members) then the statistical significance to you is 100%.

silver_tt

You can lead a horse to water..............

BlueShell

Except that's now how statistical significance works. With the number of 991.1 cars sold, surely this issue should be more common by now with more conversations around it. Yet this thread is almost four years old with not many owner contribution. Now rod bearings prematurely worn and subframe failure on an E46 M3? IMS bearing issues on the 996? Seems like a lot more owner contributed data there to support significant risk.

Even in the paper Charles Navarro wrote:

Like most performance cars, proper maintenance and car ensures longevity. Performance cars that are driven hard is going to come with some % chance of failure.

And by this accord, I'd have to write off every 996, 997, and 991. Except there are great advice here on preventative maintenance, which I'd argue is good practice for any performance car. Unless you're telling me you can drive a 991.2 and give it full beans without warming it up while ignoring oil maintenance, use cheap fuel etc.

My interpretation of the thread is that poor fuel injector maintenance, poor quality fuel, bad oil, lack of oil change maintenance, not warming up your car... etc can contribute to bore scoring. But are all of those things to be omitted from owning a 991.2 or any other performance car? No.

For what it's worth, I'm not saying that bore scoring isn't real. I'm just saying there I'd like to see more community contributed data to get a better sense of risk. And there is inherent risk with most performance car if not maintained thoughtfully.

Fullyield

I do not disagree with anything you say except your dismissal of pkalhan’s point by discounting the extent to which engineering and material choice (the use of Lokasil, Alumsil, tight piston to sleeve clearances, etc.) contributes to the problem as explained by Mr. Navarro. While proper maintenance and driving (which I frankly assume as a given among the members of this forum) could be a contributing cause, one can avoid the potential engineering defects by getting a 92A engine as pkalhan suggests. It is a reasonable conclusion on his part given the known facts and science discussed above…..even if that statement offends some 991.1 owners …….of which I am a member.

IXLR8

I remember reading something about rod length vs bore.

Fullyield

Good point. I agree. Another potential issue.

Charles Navarro

Most certainly a contributing factor. With a fixed deck, you typically have to shorten the pin height in the piston and/or shorten the rod, making the rod/stroke ratio less favorable. However I think lack of bank specific pin offsets in the piston are likely a larger contributing factor. Coupled with really tight piston to cylinder clearances and stresses in the castings leading to the bores tightening up at BDC where they meet the main bearing saddles all stack up. Finally add in M1 0w40 which is formulated to the min viscosity permissible for the sake of improved fuel economy along with high fuel dilution and long drain intervals and it's a perfect storm.

Using better oils with shorter drain intervals is the single best thing you can do if you own one of these cars.

Looking to buy one you need to do a PPI including bore scoping and used oil analysis if possible.

That said, like I've said before, the failure rate is much lower for the MA1 engine than its predecessor, but as the cars age, I expect to see more issues. 10 years ago it was mostly IMS bearing failures that was taking out M96 engines and now it's almost 100% bore scoring failures.