Well, I've had my C5 coupe for a year and half now and it's been great. This summer started after being in winter storage and on a tender. Well, since the beginning of the summer every time I start the car up it spits black carbon and condensation out ALL the time! Sometimes it doesn't happen, but sometimes it doesn't. Now I haven't narrowed it down to like, it only does it when i get on the car and then go park and start it back up or when it was sitting for awhile and then start it up after sitting. Cause it does it for both.

Also, I have ran through three quarts of oil since my last oil change and I have about 31% oil life left, I don't know if this is a whole separate problem or if this is part of the problem with the start up also. It starts right up, no hesitation ever and also has about 74,000 miles on it.

Thanks guys, Sorry for being all over the place with this post, but I am out and doing this from my phone. (NOT driving of course! Can't stand those people! haha)

Edit: the inside of my exhaust tips are black and very thick.

 

You may have a better response if you post in the tech section.
But if you have gone through 3 quarts of oil than I would think that is above normal and you are most likely getting quite a bit of blow by.
Do your exhaust tips turn black after a short drive, cause I have heard that is caused by the burning of oil.
Also some condensation is normal and can seem like a lot at times.

 

Thank you, i will repost this in Tech and yeah, they are very black!

 

Im not sure how the pcv system works but I know it does suck some oil into the intake which is why many people get oil catch cans, so Im wondering if your pcv valve has stopped functioning correctly and is not filtering the oil out of the air like it is supposed to. I know pcv stands for positive crankcase ventilation so it is constantly pulling air that is contaminated with oil and putting it into the intake when it is working like it should so if it is stuck open for some reason it could be allowing more air/oil to pass into the intake.

 

Ahhh, alright. How does the oil catch can work? Is it an easy DIY mod or more for an experience person?

 

From what I have seen it is very easy to install, and I will be getting one myself soon hopefully.
And it works by filtering the oil out of the air, not sure how it goes about doing so though, but usually people will get a couple of ounces of oil every oil change and the just dump it out. But if I was you I would pull the pcv valve out and check to see if its clogged or stuck. I know on older cars you should be able to hear it rattle and if it looks dirty or you dont hear a rattle you could replace that to see if that works being that its not that expensive.
But im no expert so see what the guys in the tech section cause I see you have already posted, Im sure you will have some answers by the morning.

 

Thank you! I appreciate your help!

 

You are welcome

 

Sounds like a good and also a cheap place to start.

It is basically an air oil separator similar to what is used on a lot of aircraft piston engines. It basically diverts the vented air from the crankcase through a mesh filter, kind of like really course steel wool, and allows the oil enough time to condense into the reservoir of the can which cuts down on the amount of oil mist to be recycled into the plenum.

 

Sounds like there may be a few different things going on!! You didn't say just HOW much and how LONG you drive at a time!! Stock mufflers or what type after market system!! Living in Illinois,,we generally have fairly high humidity numbers. Stock or the large stock size mufflers have a LARGE area to collect condensation,,and unless you drive it fairly regularly with some higher speeds you may be surprised at just how much water has condensed in there!! Have you checked your air filter?? A dirty one can help it run a little richer!! An oil catch can can be another help too!! The oil consumption can be a couple things too. There were some years that had lower tension piston rings,,and if you run around town in lower gears it can encourage the higher RPM/low engine load scenario that can let the rings kinda float instead of developing enough cylinder pressure that forces the rings into a better seal. If this is the case putting a little more load on the motor can help(not cure) the problem. If there has been a lot of city driving with not so good maintenance and possibly cheap gas,,the rings could be carboned and slugged up not letting them move freely to do their job!! get some Techron or Seafoam, and run it in your gas for a few tanks and make a few good long drives and see if that helps. also you can add Seafoam to you oil for a treatment before an oil change,,,might helps get things cleaned out. Just a few ideas!!

 

My 1st guess would be valve seals-small block Chevies of old would puff smoke on startup when the valve seals were getting worn. The deal is oil would leak into a cylinder that happened to have an open valve at shutdown-on startup, that oil gets burned and any warm restarts had no issue.