Blackness! Smoke under boost

1698 Views 43 Replies 14 Participants Last post by Heavymetals, 4 d ago

Ablackcts

Discussion Starter · 17 d ago

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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adnull46

· #41 · 11 d ago

Ablackcts said:
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?

I have a 2008 cts, it has been using up oil for awhile, I just recently replaced the air filter and when I removed the air intake, the pcv valve hose slipped out of the intake hose and it was oily, I unclipped the hose on the pcv vavle and there is oil there also. I have yet to fix it until the weekend, but I believe the pcv valve is either stuck or bad altogether. But I came across some posts about it, the car runs but seems to stumble, not smooth, there is no smoke from the exhausts at all, I haven't pulled the plugs to check on them, but both cat converters have been replaced and it has a p0420 code right now, so either the pcv vavle caused the oil to get into the previous cats? I'm going to replace the 2nd o2 sensor on the passenger side and clear the codes. But a bad pcv valve can cause the engine to use up oil, it has been about half a quart a week if driven often. It is our spare car, has over 360k miles on it.

adnull46 said:
I have a 2008 cts, it has been using up oil for awhile, I just recently replaced the air filter and when I removed the air intake, the pcv valve hose slipped out of the intake hose and it was oily, I unclipped the hose on the pcv vavle and there is oil there also. I have yet to fix it until the weekend, but I believe the pcv valve is either stuck or bad altogether. But I came across some posts about it, the car runs but seems to stumble, not smooth, there is no smoke from the exhausts at all, I haven't pulled the plugs to check on them, but both cat converters have been replaced and it has a p0420 code right now, so either the pcv vavle caused the oil to get into the previous cats? I'm going to replace the 2nd o2 sensor on the passenger side and clear the codes. But a bad pcv valve can cause the engine to use up oil, it has been about half a quart a week if driven often. It is our spare car, has over 360k miles on it.

Also, in some videos I watched, the pcv valve design was very poor, as in the holes aren't big enough to handle the air, so they say to drill out the holes to make it more efficient

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RocketSled

· #42 · 11 d ago

The function of the PCV valve is to act as a checkvalve between the sump and intake manifold. In a carbureted car, it keeps a backfire out the intake manifold from going down the tube to explode the bottom off the motor. Not sure it actually matters for an engine with a supercharger. But anyway... in normal operation, gasses from the oil sump are drawn through the valve to be mixed in to and burned with the intake charge. Since a lot of that is vaporized oil, the lines will be oily. It's normal for there to be some oil. For the same reason people run a catch can.

The PCV valve is unlikely to be your problem, IMO.

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BlueCoupeV

· #43 · 11 d ago

5ft24 said:
CAI doesn't provide vacuum. It provides fresh air that has been filtered and metered by the MAF to replace the air and oil fumes pulled through the PCV or catch can.

This is exactly why my car runs a little rich now, it was pulling additional air through the pcv. Now with the cai capped, the additional air isn't there but at least its all clean going in.

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Heavymetals

· #44 · 4 d ago

5ft24 said:
CAI doesn't provide vacuum. It provides fresh air that has been filtered and metered by the MAF to replace the air and oil fumes pulled through the PCV or catch can.

Some CAI's have a fitting that supplies vacuum just like a fitting does on the intake manifold.

That is the line you connect to the catch can outlet.

On my V1 the supercharger had a fitting for supplying vacuum for the brake booster which had a one way valve. I "T'd" off that fitting for the catch can.

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