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2013 Cruze LT
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Discussion Starter · #1 · (Edited)
Not sure if this will get any traction in this sub forum, but I will try. I blew the V band clamp tonight and was going over the exhaust. The inside of the turbo outlet was covered in black soot as well as the inside of the downpipe. I assume this is unburnt fuel. Would this be a by product of the tune? Is it expected? I assume without a wideband, it may be hard to tell? Looking at other turbo pictures, they aren't near as black as mine is. Any thoughts are appreciated.
 

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If I had to guess it would be because of the tune. My tailpipe has some black soot as well with a tune. It could've happened without the tune, I just never paid attention before hand. However my Hyundai used to have black soot as well on an stock non-turbo engine. So personally I wouldn't be concerned about it. Although I would be curious to know why.

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What are your Fuel Trims like? Might have a boost leak and causing a rich condition. The tune will command the same fuel ratio as stock, so it shouldnt be tune related. This is likely due to a maintenance issue.
 

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2013 Cruze LT
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Discussion Starter · #4 ·
What are your Fuel Trims like? Might have a boost leak and causing a rich condition. The tune will command the same fuel ratio as stock, so it shouldnt be tune related. This is likely due to a maintenance issue.
I have boost leak tested the car into oblivion lol, only small leak is from atmospheric bypass valve and its a very small hiss, in the past had many leaks (intake manifold, throttle body). From 20-10psi on boost leak test it takes over 40 seconds which I believe is more than acceptable. I ran some diagnostics today, will check fuel trims once I am back at pc. Long term trims I suppose?
 

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2013 Cruze LT
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Discussion Starter · #6 ·

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Discussion Starter · #7 ·
I guess it's good.
 

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We run a richer AFR at wide open throttle than the stock tune, which is quite lean due to the low boost. It's normal to see some soot with a tune. AFR at part throttle and idle is the same as stock though.
 

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2013 Cruze LT
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Discussion Starter · #9 ·
So an update to this, seems lately the lftf are way off, as the engine heats they get worse... How could that be? Seems to run pretty good, am I just looking into the numbers too much? (I just put green giants in, so I am watching this on purpose) Not sure where to ask questions, nothing against Jerry, but he just sends one sentence back and an updated tune. I would like a little more.

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I've been chasing a similar rich issue, but definitely seems like a boost leak here (according to BNR) still yet to verify the exact leak though. Not an issue from changing to 42# injectors from stock. Plugs are quite black with soot/carbon. It's not a tune issue either, just really hard to find this boost leak. I've been searching but haven't found it yet. Can't 100% verify it's a boost leak until it's fixed though...
 

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2013 Cruze LT
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Discussion Starter · #11 ·
They aren't going quite as negative with recent tune and plug updates, but it's still weird to me. Car seems to run fine... I guess it's a dont worry about it. I got rid of the NGK BKR plugs and got new AC Delco ones, seems to burn cleaner, but I dont know if that would affect fuel trims, maybe?
 

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2013 Cruze LT
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Discussion Starter · #12 ·
Still dealing with this, its very weird as the engine heats they get more negative... What does that mean? Just as in the graph above.
 

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