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Dean · 2009-01-21, 08:03 AM

First engine diagnosis...

While I initially did not see anything other than blow by looking symptoms on the pistons of the 2004 block, while the piston guys were having an initial look at them a large chunk of ring land 2 on one pistons fell out. Thus it was more than just ring wear on a 100K mile engine.

After talking to them for a while, my understanding is that ring lands really only fail under detonation.

That says my tune likely killed both engines. I guess it is time to dial back the boost, use 100 octane and/or change to forged pistons the last of which was the plan anyway.

I hope to get the '07 into the garage and compression tested today and maybe get it pulled. Any bets on which cylinder is down? I think people say #4 is the problem child, but I still don't understand that as it is closest to the fuel input... Guess I need to look at the rail layout again.

I also determined that some idiot reset the ECU after the failure before pulling codes and checking advance multiplier, so all that data is gone and no misfire hint as to which cylinder went.

And did I mention that the '04 cylinder sleeves appear to be made of pretty tough stuff. 85K stock and 15K boosted and you can still see some of the machine/honing marks in the piston area of the sleeves.

2009-01-21, 08:03 AM	#22
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	First engine diagnosis... While I initially did not see anything other than blow by looking symptoms on the pistons of the 2004 block, while the piston guys were having an initial look at them a large chunk of ring land 2 on one pistons fell out. Thus it was more than just ring wear on a 100K mile engine. After talking to them for a while, my understanding is that ring lands really only fail under detonation. That says my tune likely killed both engines. I guess it is time to dial back the boost, use 100 octane and/or change to forged pistons the last of which was the plan anyway. I hope to get the '07 into the garage and compression tested today and maybe get it pulled. Any bets on which cylinder is down? I think people say #4 is the problem child, but I still don't understand that as it is closest to the fuel input... Guess I need to look at the rail layout again. I also determined that some idiot reset the ECU after the failure before pulling codes and checking advance multiplier, so all that data is gone and no misfire hint as to which cylinder went. And did I mention that the '04 cylinder sleeves appear to be made of pretty tough stuff. 85K stock and 15K boosted and you can still see some of the machine/honing marks in the piston area of the sleeves. __________________ I am a Commodore PET --- Now get off my lawn you kids... Last edited by Dean; 2009-01-21 at 08:59 AM.