Hello everyone. When I accelerate hard I've noticed some black smoke coming from the exhaust. From what I have found that means unburned fuel. I have really started to notice it since the exhaust work was done and thought it was just something burning off but it has continued. Do you think that because I have a freer flowing exhaust - y-pipe, custom 2.5" catback with 5th gen muffler - and the stock intake that the engine isn't getting enough air to burn all the fuel at wot? If that's the case, I am open for suggestions on an intake that doesn't make alot of noise and one that I don't need to cut a hole for.

Thanks

 

sounds like its your oil rings aren't doing their job and some oil gets into the combustion chamber and gets burned up with the fuel. pray that its not that because that's a h$$$ge job!

 

It runs fine, smooth and strong and I still get good gas mileage, 26-27 on highway, 22-23 in city unless I am really flooring it then it goes down to 20. So I don't know.

 

i hope your not burning oil

 

burned oil will create a blue smoke. it's usually normal to have some black smoke come from the exhaust once in a while when accelerating becuase your fuel mixture is richening up.

 

Black smoke generally means your engine's running too rich. I honestly don't think any oil is being burned with the fuel because that smoke would be greyish/blueish...definately not black. I had a Nissan Stanza with just about the same problem & I ended up replacing the PCV valve & O2 sensor. In my case, it lit up the check engine light, but from what I understand, an O2 sensor can malfunction without tripping the light. Run a diagnostic on your ECU & see if you can pull a code anyways. Good luck.

 

I am over due for my 100k maintenance. Maybe I'll find something to explain it.

 

I doubt it is oil for the same reason as posted above. My guess is an O2 problem. If you had exhaust work done, was anything done around the O2 sensors that could have messed them up? Check the wiring, correct part, and if they're tight. If problem still exists, check the basics (air filter, plugs, PCV, etc...)

A little black smoke every once in awhile under hard acceleration is normal. Normally it is a "puff" when you first get on it. If it steadily continues to smoke while you are accelerating, then it is a problem worth investigating.

Dave

 

I was gonna say the same thing, its not burning oil Burning oil is blueish smoke.

Your running rich, its one of 2 things, either your 02 Sensors are dead or your knock sensor crapped out.

 

It is normal to get a little black smoke under hard acceleration if you have a Y pipe. This is because you get rid of two cat converters so there will be a little more hydrocarbons in your exhaust.

Check your plugs. I had a problem with the denso iridiums and my car would blow thick black smoke under wot. Put in NGK vpower plugs and smoke is gone. Runs better too.

Good luck.

 

If it were the knock sensor, he'd probably be complaining of more than just a little black smoke. Check out the cheap stuff first (ie: O2 sensor/PCV valve/etc), but at least run a diagnostic on your ECU, even if your CIL isn't lit.