|
|
|
|
Thread Tools | Display Modes |
09-19-2010, 09:27 PM | #1 |
Scooby Specialist
Member#: 52314
Join Date: Jan 2004
Chapter/Region:
South East
Location: Following the green weenie
Vehicle:... 02 and 04 WRXs! 2020 G70 3.3T RWD |
Lean Cylinder?
Sorry for the double post, but I think this is better suited here. I'm trying to figure out if this is what caused my piston to melt like butter. Here's the thread about it. I'm at a loss at the moment http://forums.nasioc.com/forums/show....php?t=2057556
* Registered users of the site do not see these ads.
|
09-22-2010, 05:54 PM | #2 |
Scooby Guru
Member#: 133146
Join Date: Nov 2006
Location: SC
Vehicle:07 FPgreen 7.37@95 WRX VF39+E85 12.0, 121mph |
bump for him, I just want to know what you guys think happened
|
09-22-2010, 06:23 PM | #3 |
Scooby Guru
Member#: 32669
Join Date: Feb 2003
Chapter/Region:
SCIC
Location: Woodland Hills
Vehicle:2007 2.34LR, EFR7670 LINK G4+ hybrid STi |
You got hella lean at the wrong time probably in boost. If you have an EGT gauge I'm sure you would have seen a big rise in temp before failure. Motoryder may have a thread somewhere about his melted piston adventure.
|
10-01-2010, 09:40 AM | #4 |
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
Any more input? I had a very similar failure recently. My pics are in the linked thread in the OP.
I wasn't able to find much detail about Motoryder's melted piston. |
10-01-2010, 09:53 AM | #5 |
Scooby Guru
Member#: 3687
Join Date: Jan 2001
Chapter/Region:
MWSOC
Location: St. Paul, MN
Vehicle:MY99 GF4 JDM 6spd NF Performance |
It could possibly be a cracked ringland that started the mess. The cracked ringland will cause scuffing, later enough scuffing for blowby, then oil, misfires, pre-det, then major piston failure and melting.
You'd have to take the piston out, make sure the rings don't turn so you know where the gap ends are, then inspect the piston to narrow in possible causes. |
10-01-2010, 10:45 AM | #6 |
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
Yeah, the rings won't move since they are destroyed right by were the hole melted through. Not sure I could even tell if there was a local crack in the area now...
|
10-01-2010, 11:45 AM | #7 |
Scooby Specialist
Member#: 52314
Join Date: Jan 2004
Chapter/Region:
South East
Location: Following the green weenie
Vehicle:... 02 and 04 WRXs! 2020 G70 3.3T RWD |
That's exactly how mine looks. I still haven't been able to get in touch with my tuner to get the files from my tune emailed to me. And haven't sent my injectors off as I have been toying with going with a 68HTA.
If there was a cracked ringland it would have to be small. As in now gone in the torched section of the piston. It is hard to tell as the rings are now fused to the piston. Could just det cause the erosion/ melting? I ask because I imagine it as a force acting on the piston in a way that would "break" the piston not melt it like ours. yaya20, what kind of pistons were you running? |
10-01-2010, 12:10 PM | #8 |
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
|
10-01-2010, 12:12 PM | #9 |
Scooby Specialist
Member#: 52314
Join Date: Jan 2004
Chapter/Region:
South East
Location: Following the green weenie
Vehicle:... 02 and 04 WRXs! 2020 G70 3.3T RWD |
^^^ With that being said, I find the ringland thing highly unlikely. With my stock cast one sure, but not with a forged piston like that. They both did however, melt about the same way. This is great
|
10-01-2010, 12:13 PM | #10 |
Scooby Guru
Member#: 32669
Join Date: Feb 2003
Chapter/Region:
SCIC
Location: Woodland Hills
Vehicle:2007 2.34LR, EFR7670 LINK G4+ hybrid STi |
He's my neighbor and its possible he didn't post the failure here. You need to be very hot to melt a piston like that, way beyond normal combustion temps. About the only thing I can think of that would allow that would be an extremely lean condition. Those where his findings also.
|
10-01-2010, 12:20 PM | #11 | |
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
Quote:
|
|
10-01-2010, 12:24 PM | #12 | |
Scooby Specialist
Member#: 52314
Join Date: Jan 2004
Chapter/Region:
South East
Location: Following the green weenie
Vehicle:... 02 and 04 WRXs! 2020 G70 3.3T RWD |
Have you had the tune looked at closely or by another tuner for a second opinion?
Quote:
|
|
10-01-2010, 12:56 PM | #13 |
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
Tricky situation, but no. Not yet.
|
10-01-2010, 02:31 PM | #14 |
Scooby Newbie
Member#: 196786
Join Date: Dec 2008
|
That damage is in no way caused by a broken ring or ring land. Its lean
|
10-01-2010, 10:34 PM | #15 |
Scooby Newbie
Member#: 142017
Join Date: Feb 2007
|
Faulty injector
fuel system problem tune check all three |
10-01-2010, 10:53 PM | #16 |
Scooby Specialist
Member#: 108089
Join Date: Feb 2006
Chapter/Region:
MWSOC
Location: Minnesota
Vehicle:2003 WRX NF Performance |
get the injectors checked out
what injectors? |
10-02-2010, 10:49 AM | #17 |
Scooby Newbie
Member#: 220799
Join Date: Aug 2009
Chapter/Region:
International
Location: Taiwan
Vehicle:2006 Impreza WRX WRC Blue |
This looks definitely lean and might be caused by pre ignition due to being overly lean. There are no DET marks on the piston crowns. Pre ignition is the worst that can happen. Temperatures and cylinder pressures can go skyhigh in the blink of an eye. Many times it cannot be heard in the DET cans and no knock shows up. Even AFR may not show excessively lean as most people measure average AFRs of all 4 cylinders.
Most likely faulty injector or perhaps a clogged one. Also check wiring to make sure injectors are ok and clean mating connectors, etc. Good luck on the rebuild. Cheers, Jasper Kopinga CS Racing Taiwan. |
10-03-2010, 01:50 PM | #18 |
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
I was running DW850s, they have been inspected and given a clean bill of health
|
10-03-2010, 05:35 PM | #19 |
Scooby Guru
Member#: 64908
Join Date: Jun 2004
Chapter/Region:
Tri-State
Location: Tuning 8/9sec Subies all over
Vehicle:10.8 XT+9.2@155 GR+ 9.1/157mph 2015 STI |
Detonation in that cylinder, look at all the pitting on the piston dome. probably cracked a ring land and it was burning oil. When you burn oil with your gas you end up with very little octane, which would cause the cylinder to start to run super hot and melt.
Check your knock correction range, if it was around the stock setting of 6100 and you were revving to say 6800-7k that's about 1k rpms of no knock control, so it would not pull any ignition, or show a knock count. Not to mention it would be in the range were the td04 is pushing some seriously hot air which would tend to detonate a lot. What was your timing and wideband AFR.. Hopefully you had a wideband or were tuned with one at least. Lots of timing or very lean tune or both.. Look at your number 1 piston as well.. Corner nice and shinny. Your EGTs were probably pretty high when that melted. If it was a bad injector only 1 piston would look like it took some serious heat. |
10-04-2010, 04:17 PM | #20 |
Scooby Specialist
Member#: 56754
Join Date: Mar 2004
Chapter/Region:
NESIC
Location: Mass
Vehicle:2004 Hybrid 2.5XTR RIP Chris@EFI |
bump for more answers?
|
10-04-2010, 05:19 PM | #21 |
Scooby Specialist
Member#: 52314
Join Date: Jan 2004
Chapter/Region:
South East
Location: Following the green weenie
Vehicle:... 02 and 04 WRXs! 2020 G70 3.3T RWD |
I think the answers are in the post above
|
10-04-2010, 05:25 PM | #22 |
Former Vendor
Member#: 60836
Join Date: Apr 2004
Chapter/Region:
SCIC
Location: Torrance, CA
Vehicle:2006 Mod Class STI TIMEATTACK!! |
Like jkopinga said; pre-ignition. Melts holes in pistons really quick. Probably happened due to a lean condition and a lot of knock.
This is one of the better write-up on pre-ignition and detonation online: http://www.streetrodstuff.com/Articl...ne/Detonation/ |
10-04-2010, 06:29 PM | #23 |
Scooby Specialist
Member#: 58647
Join Date: Apr 2004
Chapter/Region:
Tri-State
Location: Here for now...gone tomorrow
Vehicle:02 Exedy Carbon clutches SLIP and SUCK $! |
While my piston wasn't on a boosted application it was melted from Detonation.
It was a 13.5 compression engine on 93 octane but I let a moron ride it and he just kept WFO till it melted |
10-05-2010, 06:19 AM | #24 |
Scooby Newbie
Member#: 220799
Join Date: Aug 2009
Chapter/Region:
International
Location: Taiwan
Vehicle:2006 Impreza WRX WRC Blue |
Have had one Spec C engine blow the 2nd time now :-( It's probably also caused due to pre ignition. Checked everything. Fuel pump, injectors, etc. etc.
Had the DET cans on and nothing to be heard until there was suddenly a big cloud of smoke and oil splashing everywhere in the engine bay :-( **** happens! Cheers, Jasper. |
10-05-2010, 10:30 AM | #25 | ||
Scooby Specialist
Member#: 130354
Join Date: Oct 2006
Location: KS
Vehicle:2011 535xi |
Quote:
Quote:
|
||
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
System too lean, Cylinder 4 misfire and knocking sound... | KarmaWagon | Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) | 6 | 10-22-2007 07:47 AM |
And the lean cylinder is ? | yzblazr | Newbies & FAQs | 12 | 04-07-2006 09:53 AM |
Any real truth that the 2.5 RS runs lean on 1 cylinder? | cjfike | Normally Aspirated Powertrain | 0 | 04-29-2005 12:14 PM |
the old lean cylinder | White 2.5rs | Normally Aspirated with bolt-on Forced Induction Powertrain | 1 | 06-11-2004 02:38 AM |
Which cylinder was running lean? | IMPBOY | Normally Aspirated Powertrain | 2 | 11-18-2000 12:15 AM |