AronZ28

I was crawling up under my car the other day, I have an exhaust cutout that dumps under the rear seat. I was looking on the floorpan back there and it was black!!! I could also see little carbon chunks right after the pipe. I have had my exhaust dump under the back seat for 5 months and its already built up this black. I know my car uses 1/2 quart of oil every 3000 miles, nothing really. And the car doesn't smoke.

So am I running rich? I bought the car with 41K miles and it now has 60K. I have changed the oil and filter every 3K. I haven't done anything to the engine other than changed the coolant. I have also noticed my gas mileage is down to 16-17 MPG in town for the past couple of months, only 20-21 highway.

Mindgame

Probably.

You ever pull a spark plug and take a look at it? Spark plugs can tell you a lot about how an engine is running.

-Mindgame

AronZ28

okay, I'll try that. Its just that the car always starts right up, has plenty of power, never stumbles or misses, it seems to run fine. Maybe the idle is a little rougher than it used to be, but it isn't that noticable. And the SES light isn't on, but can it still have a code stored in there, even though the light isn't on

BirchMan98z

Even a brand new car at WOT will spit black smoke for a second or two. Watch cars on the dyno. '04 cars with 1500 miles will spit black smoke. It's just carbon deposits. Toss in some gum-out fuel system cleaner, that might help a bit, but it's pretty common and I wouldn't worry too much about it. Better to run a tad rich than a tad lean in my opinion.

AronZ28

I do run her pretty hard, I probobly go to WOT about every other time I drive her. I tried to get the sparkplug out, but I don't have a sparkplug socket and I couldn't get it out by hand. I'm taking her into the shop for some brake work and a leaking pinion seal, I'll have the mechanic look at it then.

SMAX

the more the engine flows when the cutout is open, it just makes it run richer. just like when people put headers on. i dont think it is anything to worry about.

teke184

when ever you burn a petroleum based material, the byproducts of the reaction are water, *** and carbon

even if it is runny perfectly it will still deposit carbon. it's the nature of a gasoline engine. and when you think about how much exhaust is being dumped out that cutout, for thousands of miles...you can imagine why there is some build up.

BirchMan98z

'zackly.

AronZ28

i was wondering if I had my panties up in a bunch over nothing. I guess its better to be paranoid than lax about this type of stuff though. i'll have autozone do a code scan for free tommorrow, still no SES though.

BirchMan98z

running rich or lean won't set of SES I don't think, unless it's an extreme case in either direction. Plus, auto zone won't be able to scan that. You have to get to a dyno to have your air/fuel ratio checked.

AL SS590 M6

Yes it will. They can scan for the O2 being out of spec showing a rich or lean condition. You don't want to tune by them but they'll show rich or lean as compared to normal.