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Blackness! Smoke under boost

1680 Views 43 Replies 14 Participants Last post by  Heavymetals
I am trying to determine the cause of blue smoke under WOT, I have a catch can that was installed MAYBE 1000mi ago. The previous owner did not have one. I am seeing large puffs of blue smoke when I punch it. Also, my exhaust has ALOT of black carbon residue. I put plugs in about 1000mi ago as well, and I checked them the other day and saw they also have the black soot on them. It is NOT wet oil, and the catch can is working for sure. I am thinking about pulling the S/C lid and checking/ cleaning the brick. Could it still be residual from not having the catch can?
On the note about the lid, are those gaskets reusable?
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Running rich?

Burning oil?

You can toss it in the freezer for 15 minutes and try but new ones are cheap.
Sounds like blow by (piston rings). How many miles on the motor?
130k. I should have also specified that I have no cats, no rear 02 sensors and under a load, I run 11 afr.
Do a compression check. Sounds like it is time for a motor refresh.
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Is it using oil? With large puffs every time you step on the gas hard, if it's burning oil, I'd expect the oil level to drop pretty quickly.

The engine has a tune, apparently, for the cat/O2 delete and AFR target. It could just be the way the tune is set up. Dumps extra fuel when the boost shoots up to limit knock maybe... what do you know about any ECM changes?
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I am trying to determine the cause of blue smoke under WOT, I have a catch can that was installed MAYBE 1000mi ago. The previous owner did not have one. I am seeing large puffs of blue smoke when I punch it. Also, my exhaust has ALOT of black carbon residue. I put plugs in about 1000mi ago as well, and I checked them the other day and saw they also have the black soot on them. It is NOT wet oil, and the catch can is working for sure. I am thinking about pulling the S/C lid and checking/ cleaning the brick. Could it still be residual from not having the catch can?
On the note about the lid, are those gaskets reusable?
These engine's suffer from catastrophic self-detonation,
especially the two rear cylinders, as they run hotter than
the other six.

-throttle open-
Generally speaking, if you are accelerating hard, the oil is being pulled into the engine via piston movement, or the vacuum generated by the high rate of piston movement moving down. This in turn generates a depression across the intake valve.

-throttle closed-
Generally speaking if you are decelerating you most likely have bad valve guides.

First, pull the plugs and look for a bad cylinder.

A compression or leak-down test might need to be completed next.

If nothing there, then proceed to look into the Blower issue.

Even though you just replaced the spark plugs about 1,000
miles ago, it appears something has changed.

My suggestion is you pull the plugs ASAP,
as it appears something has happened.

You stated that the 'catch can' is working.

If that means it is collecting a lot of oil, that
may also mean an engine sealing issue. . .

I would be concerned about driving the car until
you determine if the engine has been harmed.

Cheers
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make sure closed loop is in operation ? if the 02's are sooty then it sounds like they are not operating correctly or staying in open loop, even if the 02's get sooted up an easy few mins of idling at stoich should clean them up, not having rear 02's can be bad for some ecu's they will default to a rich running for safety and nothing u can do about it except plug them back in even if disabled some just have to be physically plugged in,

was your commanded afr shown using wideband or is it just what is said to be commanded ? if 11:1 is commanded someone can just adjust the fuel tables to read what ever on the actual wideband so may be richer then u think or its defaulting to a richer state for a reason, or issues like mentioned above to be tested for
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make sure closed loop is in operation ? if the 02's are sooty then it sounds like they are not operating correctly or staying in open loop, even if the 02's get sooted up an easy few mins of idling at stoich should clean them up, not having rear 02's can be bad for some ecu's they will default to a rich running for safety and nothing u can do about it except plug them back in even if disabled some just have to be physically plugged in,

was your commanded afr shown using wideband or is it just what is said to be commanded ? if 11:1 is commanded someone can just adjust the fuel tables to read what ever on the actual wideband so may be richer then u think or its defaulting to a richer state for a reason, or issues like mentioned above to be tested for
If an engine runs rich, for to long, it will take the rings out.

Sometimes you can tell 'quickly' by looking at the oil,
as it can, if left rich for to long turn the oil black.

You can then confirm by pulling the spark plugs. . .

----------------------------------------------------

Some think running an engine rich is safer than lean. . . .

An engine running rich, particularly on E85 will also
leave end-gases behind. Those end gases end up
behind the upper ring lands.

Since they did not burn on the last cycle, they are
now warmed up. On the next cycle they are primed
for self-detonation.

Cheers
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Is it using oil? With large puffs every time you step on the gas hard, if it's burning oil, I'd expect the oil level to drop pretty quickly.

The engine has a tune, apparently, for the cat/O2 delete and AFR target. It could just be the way the tune is set up. Dumps extra fuel when the boost shoots up to limit knock maybe... what do you know about any ECM changes?
So the previous owner had a Diablo tuner on it, I took that and saved it to HP Tuners. So the Diablo is gone now, but has the same tune as the Diablo. I have not adjusted any tables with HPT, I just used it to turn off the o2 sensors.


make sure closed loop is in operation ? if the 02's are sooty then it sounds like they are not operating correctly or staying in open loop, even if the 02's get sooted up an easy few mins of idling at stoich should clean them up, not having rear 02's can be bad for some ecu's they will default to a rich running for safety and nothing u can do about it except plug them back in even if disabled some just have to be physically plugged in,

was your commanded afr shown using wideband or is it just what is said to be commanded ? if 11:1 is commanded someone can just adjust the fuel tables to read what ever on the actual wideband so may be richer then u think or its defaulting to a richer state for a reason, or issues like mentioned above to be tested for
Reading the wideband, AFR under boost is 11:1, idle , no boost conditions is 15:1 or a little under ish. I will check for closed loop this weekend for sure.


If an engine runs rich, for to long, it will take the rings out.

Sometimes you can tell 'quickly' by looking at the oil,
as it can, if left rich for to long turn the oil black.

You can then confirm by pulling the spark plugs. . .

----------------------------------------------------

Some think running an engine rich is safer than lean. . . .

An engine running rich, particularly on E85 will also
leave end-gases behind. Those end gases end up
behind the upper ring lands.

Since they did not burn on the last cycle, they are
now warmed up. On the next cycle they are primed
for self-detonation.

Cheers
The oil IS already black only after 1500mi but it is only on its first oil change since I have owned it. I have some AMSOIL I am about to put in it after I do the flush on the current oil and since the oil leaks are fixed. I only run 91-93 with no ethanol.

I will be doing a compression test this weekend and I will report back with photos and video as soon as I can.
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So the previous owner had a Diablo tuner on it, I took that and saved it to HP Tuners. So the Diablo is gone now, but has the same tune as the Diablo. I have not adjusted any tables with HPT, I just used it to turn off the o2 sensors.



Reading the wideband, AFR under boost is 11:1, idle , no boost conditions is 15:1 or a little under ish. I will check for closed loop this weekend for sure.



The oil IS already black only after 1500mi but it is only on its first oil change since I have owned it. I have some AMSOIL I am about to put in it after I do the flush on the current oil and since the oil leaks are fixed. I only run 91-93 with no ethanol.

I will be doing a compression test this weekend and I will report back with photos and video as soon as I can.
When you pull the spark plugs to do the compression test, be sure
you keep them in order after looking them over very carefully.

You should talk to @07GTS more about those O2 sensors.
if ur running about the 15:1 most of the normal driving and ur 02's are still sooty then its sounding like something is being introduced to cause the soot, take plugs out and check even look in with a little camera if u have one to check the piston tops see if they are oil burnt on the tops, if they are looking ugly then its not a good sign, oil only gets in past the valve stem seals or rings so one is a easy fix the other is a PITA (or a good excuse) make sure your crank/rockers breathing is working good too
Well, oil could be introduced by a badly malfunctioning PCV system as well...


jus sayin
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Ok here are the compression test results:
#1 150psi took to turns to get there
The rest took 3 turns to get to the max pressure:
#2 152psi
#3 147psi
#4 148psi
#5 149psi
#6 148psi
#7 150psi
#8 148psi

No evidence of leaking rings, or worn valve stems.
I decided not to do a wet test since the dry was consistent.
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The wetness on #7 is from changing the valve cover gasket last weekend. Plus I use 100% silver anti-seize so it’s a bit runny. However, the plugs are much blacker than they were 2 weeks ago. I’m thinking the issue is running too rich. What do you all think?

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Well, one immutable fact is that blue smoke is always oil. It looks like you have fuel control problems, certainly, but blue smoke is always oil.
You still need to ferret out the oil source, while also dealing with the tune.
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PUDDLES!
I bet I had half a quart in there!! Wtf? Time to reevaluate my catch can.
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