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Old 09-18-2010, 11:29 PM   #1
340Duster
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I read mostly about cracked ringlands on the pistons, or spun bearings. It looks more like a lean condition on the cyl. Trying to figure out exactly what caused the erosion of the piston/ it melting to the bore. Sorry the second pic is from my phone.



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Old 09-18-2010, 11:33 PM   #2
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Were those marks in the cylinder, or it that from you trying to free it up??
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Old 09-18-2010, 11:36 PM   #3
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Thats aluminum of the piston melted onto the steel of the bore. The engine was running when I pulled it.
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Old 09-19-2010, 09:08 AM   #4
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Nothing?
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Old 09-19-2010, 09:14 AM   #5
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Probably. Its not like there are a whole lot of possibilities here. What mods were you running?
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Old 09-19-2010, 03:18 PM   #6
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Looks somewhat familiar... I'd start by getting your injectors checked out. Looks like cylinder 3???

Here is mine:
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Old 09-19-2010, 06:42 PM   #7
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Quote:
Originally Posted by yaya20 View Post
Looks somewhat familiar... I'd start by getting your injectors checked out. Looks like cylinder 3???

Here is mine:
Thats exactly what I came up with today, I think its an injector failure, but Idk... I suppose #3 is more prone because its probably the hottest running cylinder. I have pictures to add.
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Old 09-19-2010, 06:47 PM   #8
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I think it ran lean and melted the piston, but thats my guess, I'm looking for other opinions
It was a Cobb stage 2, then was open source tuned to run 18-19 psi on just a ported TD04. I have a large TMIC, short ram and exhaust. Thats pretty much it for engine mods.



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Old 10-02-2010, 12:05 AM   #9
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Quote:
Originally Posted by 340Duster View Post



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.

Quote:
Originally Posted by yaya20 View Post
Looks somewhat familiar... I'd start by getting your injectors checked out. Looks like cylinder 3???

Here is mine:
Lots of timing or very lean tune or both.. Look at your number 1 piston as well.. Same 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.
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Old 09-19-2010, 07:18 PM   #10
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Man thats not fun.
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Old 09-19-2010, 07:22 PM   #11
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I wish I could give you more info. I just got the results from my injector test last week and they were fine. Mine was a built ej205.

The clean piston top makes it look like the cylinder wasn't getting fuel. But it's possible that after the loss of compression the heat and the fuel washed away a lot of the carbon build up. Injector is the first thing I would check. After that I'm all ears.
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Old 09-19-2010, 07:37 PM   #12
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Yeah I am right now looking to find someone to flow test them. I'm working on a new build, only the cams from that engine are being reused. I need to figure out what caused this though. Next is to post this to the built motor discussion, people with more engine experience hang out there.

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I wish I could give you more info. I just got the results from my injector test last week and they were fine. Mine was a built ej205.

The clean piston top makes it look like the cylinder wasn't getting fuel. But it's possible that after the loss of compression the heat and the fuel washed away a lot of the carbon build up. Injector is the first thing I would check. After that I'm all ears.
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Old 09-19-2010, 07:23 PM   #13
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Here is my cylinder wall too:



My motor has not been broken down yet as I doubt anything in it will get reused.
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Old 09-19-2010, 07:52 PM   #14
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I suppose a bad coil could be an issue, but I would think you would have misfires before it got to that point of destruction.
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Old 09-20-2010, 12:11 AM   #15
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Yeah there was no CEL at all or anything other than the loss of power when the compression went to almost 0.

Have you had your tune looked at or the car logged for any issues on that side of things?

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I suppose a bad coil could be an issue, but I would think you would have misfires before it got to that point of destruction.
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Old 09-20-2010, 12:24 AM   #16
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Old 10-03-2010, 04:49 AM   #17
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Quote:
Originally Posted by 340Duster View Post
Quote:
Piston destruction can also be due to super-lean conditions, usually caused by too much timing (either from low octane or too high for the given cylinder pressure), not enough fuel volume, or a combination of both.
How does too much timing cause a lean condition?

(I don't think it's possible, but I like to ask questions in cases like this...)
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Old 10-05-2010, 11:45 AM   #18
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Quote:
Originally Posted by NSFW View Post
How does too much timing cause a lean condition?

(I don't think it's possible, but I like to ask questions in cases like this...)
i think you're misreading the comma as an inference of a causal relationship, when it's really just a list delimiter.
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Old 09-20-2010, 08:48 AM   #19
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Quote:
Originally Posted by 340Duster View Post
Yeah there was no CEL at all or anything other than the loss of power when the compression went to almost 0.

Have you had your tune looked at or the car logged for any issues on that side of things?
I had no previous CEL either. I was on the highway at about 15psi and building boost then boom and no power. I literally had zero compression in that cylinder.

I have not had the tune looked at by anyone other than the original tuner and no logging as the car was run as little as possible since the incident.

Interesting article btw.
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Old 09-20-2010, 12:28 PM   #20
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Same here, except it was around 19psi, and I had the tuner go over the map, He said all the AFR numbers and timing were within the normal range for the setup I was running. So

Quote:
Originally Posted by yaya20 View Post
I had no previous CEL either. I was on the highway at about 15psi and building boost then boom and no power. I literally had zero compression in that cylinder.

I have not had the tune looked at by anyone other than the original tuner and no logging as the car was run as little as possible since the incident.

Interesting article btw.
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Old 09-20-2010, 12:56 PM   #21
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Sounds like we are in the same boat. I'm going to see about maybe tearing down my block pretty soon and see how the skirts and rings look on the rest of the pistons. Maybe something that can show me if it was tuned too rich.

Hopefully some other folks will chime in here with some ideas.
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Old 09-20-2010, 01:34 PM   #22
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No I agree, I don't see how too rich would cause it though? I could see in the case of a bad injector, the AFR was in line with by running 3 cyls rich and one lean. That was my earlier thought.
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Old 09-20-2010, 02:42 PM   #23
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The article you linked described how it would be possible in a situation that is overly rich...
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Old 09-20-2010, 04:12 PM   #24
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Yeah, I just don't understand the lifting of the ringland, I would think in a cast piston it would simply crack. People talk about tiny amounts of fuel getting combusting and blowing the ring lands all the time.

Where's Soobaviator when you need him?
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Old 09-21-2010, 09:16 AM   #25
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If the ring were to get pinched and allow enough oil to get into the combustion chamber, then there would be detonation. Now, if the oil was to pool a little on the bottom then start to combust (oil burns hot and slow), then I could see it melting a piston in the location we both had it happen in.
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