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Discussion Starter · #1 ·
Hello everyone! So recently, I built my 2jz for boost (running 13 psi) and achieved a compression of 160 to 170 across the board after the rebuild. After getting it tuned and driving it for a couple of hundred miles, I noticed smoke coming out of the tailpipe that was not there before. So I checked my compression, and I found that I have low compression on some cylinders. I found one at 180, but I found another one at 100. My engine was built with gte rods, non-vvti pistons, arp head studs, and a gte head gasket. I am using a standalone ECU master black. I also found oil in my intercooler. Before I tear into my engine again. Does anyone have an idea why the engine would go out at such low miles? Thank you so much! any input would be appreciated!
 

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Man I feel for you… had this happen once before as well. Off chance maybe you have a stuck/bent valve(s) causing the low compression? Perhaps contact your engine builder or did you do the work yourself on the bottom end and head?
 

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Given the IC full of oil and low compression, unfortunately it's very likely you hurt the motor while tuning it. Verify that your timing sync is accurate (so that 14* commanded timing advance is getting 14*, not, say, 24* because the base timing is 10* off somehow) If the tune itself looks safe but you still hurt the engine, it's usually a problem like that. Sort that out while you are still on the hurt motor, so when you do get it rebuilt you can start fresh on a confirmed good ECU configuration.
 

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Discussion Starter · #5 ·
Man I feel for you… had this happen once before as well. Off chance maybe you have a stuck/bent valve(s) causing the low compression? Perhaps contact your engine builder or did you do the work yourself on the bottom end and head?
Thank you very much for the reply, I actually got the head and block machined professionally, but I did assemble the bottom end and the rest of the engine myself. I guess my only bet now would be to tear it down again and check what went wrong.
 

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Discussion Starter · #6 ·
Given the IC full of oil and low compression, unfortunately it's very likely you hurt the motor while tuning it. Verify that your timing sync is accurate (so that 14* commanded timing advance is getting 14*, not, say, 24* because the base timing is 10* off somehow) If the tune itself looks safe but you still hurt the engine, it's usually a problem like that. Sort that out while you are still on the hurt motor, so when you do get it rebuilt you can start fresh on a confirmed good ECU configuration.
Thank you for the reply. Unfortunately, I don't have any tuning knowledge therefore I went to get it professionally tuned. The reason why I rebuilt the motor the first time was actually because of the same issue. while we were doing pulls and the tuner was "Tuning" my ECU, everything was fine until lots of smoke came out, so I decided to take off the pipe and saw lots of oil dripping out which was not there before. After that, I slowly drove it home and did a compression test. The compression was low so I rebuilt it with the mods stated above. After the rebuild, I drove it around to break it in, and then I went to get it tuned again. Then the other day as I was driving I noticed smoke so I checked my compression and it was low (mind you I checked it after the rebuild and it was fine). Unfortunately, I already am taking off the motor but after the rebuild, I will plug in my laptop and look at the data. I don't know much about tuning but I can share the tables with you if you don't mind.
 

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Seems either one of two things happened - either the rebuild was not successful due to flawed machine work/etc, or there's a fundamental tuning problem that starts with this supposedly professional tuner. If two engines got smoked back to back by the same guy I think the first step is to follow up with him for any possible recourse.

Posting a screenshot of your timing map would be useful.
 

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Discussion Starter · #9 ·
Seems either one of two things happened - either the rebuild was not successful due to flawed machine work/etc, or there's a fundamental tuning problem that starts with this supposedly professional tuner. If two engines got smoked back to back by the same guy I think the first step is to follow up with him for any possible recourse.

Posting a screenshot of your timing map would be useful.
Well, what happened is after the rebuild, I went back to the same tuner to finish the tune we started. After I finished with him, the car was not driving right and wouldn't even go past 4k rpm under boost. So I said screw it, let me just go to another tuner; after going to a new tuner, he told me that the tune was out of wack and it didn't seem like it was even tuned. He also claimed that my timing was at 28. Anyway so, he tuned it for me, but I only made 274 horsepower. At that time, there was some slight smoke, but we thought because I was running rich. But the smoke has only increased, and that led me to do the compression test.
 

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What octane fuel? What turbo?

28 degrees at peak power on 13 psi seems doable. 28 degrees at peak torque seems aggressive.

Things like knowing how to verify ignition timing takes a $10 timing gun and 15 minutes to learn...
 

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Cracking a piston at 13 psi seems like a difficult thing to do. Its not rocket science.

1. Sync timing.
2. Set a soft timing map.
3. Dial in your air/fuels
4. Bring it up to 16-18 psi on 93 octane.
5. Bring up the timing slowly and watch for knock...
 

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Discussion Starter · #14 ·
Cracking a piston at 13 psi seems like a difficult thing to do. Its not rocket science.

1. Sync timing.
2. Set a soft timing map.
3. Dial in your air/fuels
4. Bring it up to 16-18 psi on 93 octane.
5. Bring up the timing slowly and watch for knock...
Hey thank you for the reply. Yeh I will rebuild it with forged pistons now. And I will put up my timing table after I'm done. The problem is I am in stupid Cali we don't have 93 only 91.
 

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Hey thank you for the reply. Yeh I will rebuild it with forged pistons now. And I will put up my timing table after I'm done. The problem is I am in stupid Cali we don't have 93 only 91.
But we have E85 all over the place.
 

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If you let your car sit for long periods, I wouldn't run E85, but if you drive it somewhat regularly, have at it. Can still make plenty respectable power out of a 91 octane setup. The missus' Mk4 made roughly 380whp on stock twins and an Aristo swap, the power is the easy part. Getting it to drive nicely is what takes talent.

That second picture of your cracked piston appears to have a hole in the skirt too, I would be checking the block for damage, just to be safe. While you're in there, might not be a bad idea to take the oil pan off and see how many chunks ended up in places they shouldn't be. :(

Might reach out to @Patrick94TT depending on what part of California you're in, in regards to reliable tuning.
 

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If you let your car sit for long periods, I wouldn't run E85, but if you drive it somewhat regularly, have at it. Can still make plenty respectable power out of a 91 octane setup. The missus' Mk4 made roughly 380whp on stock twins and an Aristo swap, the power is the easy part. Getting it to drive nicely is what takes talent.

That second picture of your cracked piston appears to have a hole in the skirt too, I would be checking the block for damage, just to be safe. While you're in there, might not be a bad idea to take the oil pan off and see how many chunks ended up in places they shouldn't be. :(

Might reach out to @Patrick94TT depending on what part of California you're in, in regards to reliable tuning.
Thanks Brad

Chris is my tuner, @cwtt
 

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Discussion Starter · #20 ·
If you let your car sit for long periods, I wouldn't run E85, but if you drive it somewhat regularly, have at it. Can still make plenty respectable power out of a 91 octane setup. The missus' Mk4 made roughly 380whp on stock twins and an Aristo swap, the power is the easy part. Getting it to drive nicely is what takes talent.

That second picture of your cracked piston appears to have a hole in the skirt too, I would be checking the block for damage, just to be safe. While you're in there, might not be a bad idea to take the oil pan off and see how many chunks ended up in places they shouldn't be. :(

Might reach out to @Patrick94TT depending on what part of California you're in, in regards to reliable tuning.
Thank you for the reply! Yeh I have dissembled everything and I am going forged pistons and a bore on the cylinders. I will also have the builder assemble the block for peace of mind. Just don't want this to happen with forged pistons. Will be dropping new hg and bearings as well even though they had low miles. After finished I will post up my timing table so you guys can chime in. I appreciate everyone's support! I just want to enjoy this thing it's been down for a while now and all I've been doing is dumping my savings into it.
 
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