Black soot in exhaust. Normal?
 

Hello people,
I am currently in the market for a BRZ. I have been looking around and noticed some cars have black soot in the exhaust and that the oil smells like gasoline. To me, it seems that the car is running rich and that either there is a leaking fuel injector or the piston rings are worn. I just wanted to know if this is normal in boxer engines or if the piston rings are simply worn because the previous owner didn't take care of their car.
Any insight is appreciated :)

Thanks,
oma

is it stock, or does it have headers and a tune?

It runs rich at startup while the cats are warming up. So I would say smell it after the warm up sequence is complete

Every car I've ever owned has required me to clean the tips weekly or else they would be black. Not wet, just dry black powder. I suspect it has a lot to do with my driving habits though. Since switching to E85 in my FRS I have gone about 9000 miles and the tips are crystal clear. I am intentionally not cleaning them to see how long they stay clean.

Normal af.

stock

That I agree on, but its not just a little bit of powder like my other cars, I slide my finger inside and It is PURE black. There's a good amount of it

Good point. Would it be because of the ethanol content in the fuel maybe? Would it be because of maybe the previous owner put low grade fuel inside the tank?

That's the way my stock 2013 FR-S is. Why? Because of a lot of cold starts and short trips.


:iono:


humfrz

Ethanol burns cleaner so it doesn't leave deposits as much. The black you are talking about, is it wet or just dry powder? If it's wet I would assume it's oil and I would stay away, if it's dry I would say it's just from running a little rich. But probably just someone who doesn't bother cleaning the tips and drives the car in open loop a lot.

So would you say it is because of oil dilution? I don't even want to take the risk on this car anymore. I don't think there's anyway for me to check if its an injector, worn engine or having tons of short trips.
I think its important to mention that the car is also sitting in a show room at the dealership, so I doubt it goes through many short trips.

its powder. What do you mean by "open loop a lot"

as previously stated, its probably from when your cats are cold

Short hop driving soots them up. Or a bad tune.

My 13 burned oil originally but after new long block was installed in 14 oil consumption has been nil

These cars are far from repair nightmares. Your fears are unfounded.

No, cold starts go through a rich phase in an effort to heat the cats as fast as possible. This phase tends to put out more crap.

Closed loop is where the car monitors the O2 sensor to determine how much fuel to use. When you are at all aggressive on the throttle it goes into open loop mode where it no longer uses the O2 sensor to meter the fuel and then resorts to a lookup table to determine how much fuel to use. In OL mode the car can sometimes run more rich. If I recall the 2017+ runs exclusively in CL mode though.

If it isn't wet or oily I wouldn't be concerned.

Every oil change I've done on my car in my almost 4 years of ownership the oil has always smelled a tad like fuel. I had a Blackstone analysis done on it and they said I don't have any fuel dilution, despite the smell. I wouldn't worry about it.

Well, omadab, I'm late, but I'll give you my take on your observations. Black soot on the tail pipes of this car is quite common. It runs rich at start up for emission reasons. Quite normal.

So the oil smells like gasoline - well, a little gas does escape the piston oil rings on all engines and it don't take much gas to smell up a storm. Not to worry.

Piston rings being worn, yep they all are on most engines - to a degree. I wouldn't worry about the oil rings being too warn unless you can see blue smoke coming out of the tail pipes after the engine has warmed up.

Now, back in the day, if you are listening to those old coots, a black exhaust pipe usually meant the car was running rich (it needed to have the carburetor adjusted/timing adjusted). If a car was "burning oil" (like blue smoke pouring out the tail pipes) it usually would lay down a blue smoke screen. If "smoke" was coming out from under the car, there was a good chance the piston compression rings were shot, creating blow by through the crankcase.

(hey - who yanked ol humfrz's chain?)


humfrz

Well, although short trips aren't the best life for a car, they don't usually damage it. One good "Italian tune up" (long, hot trip) usually clears it out. Mostly true of older cars, not so much newer cars - with them new fangled computer things - :)).


humfrz

PS

Well, that's your call.

I would suggest that if the car you're looking at hasn't been power modified (header - forced induction) or tracked extensively (sometimes indicated by suspension modifications), has a howling TOB, it has the transmission you like, the color you like and isn't showing any trouble codes - it's most likely OK.


PSS as you are finding out - it's real easy to over think buying a used car -:eyebulge:

You can not walk up to a random car and diagnose it's condition from the amount of soot in the tail pipe. If you have a baseline and you watch closely you may be able to notice a change but the simple presence of soot is meaningless. The tips of these cars have a nice big surface area that holds soot. Unless you clean them on a regular basis it will build up more than some cars. It is fine.

Omg. Paranoia. Move on and find another car with clean tips so you will feel better :)

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Internal combustion is on it's way out anyways. Teslas have clean tailpipes.

Thank you everyone for your two cents. I agree with @humfrz, I probably am overthinking the purchase of the car. I'll sit on it for a couple of days then make my choice... unless another beauty comes along haha

If you are worried about soot you only option is...


https://upload.wikimedia.org/wikiped...ekna_Front.jpg

However they all lie to you about zero emissions! Do you realize how much oil and gas is consumed to manufacture and maintain a car?

Short answer. Its normal.

I can't comment on the oil smelling like gasoline. But my tips are also black as shit due to cold starts. I got the cats and straight pipes after that. So atleast you don't have to worry about that =)

Run E85 my exhaust has no residue and my oil doesnt go black (my e85 is true 85% ethanol all the time)

What are you putting to the wheel? I am thinking of going E85 on my GT86. :D

Out dynos read diffrent to usa


Stock car here does about 110kw at wheels

Header and tune on petrol about 125 kw
Header tune and e85 about 135 kw


Our petrol is about USA 91, so if your on 93 petrol you will already be closer to the e85 power outputs


European 98 ron petrol is better than Australian 98 so you wont get as big a jump to e85 as in Australia

my exhaust has aidshttps://uploads.tapatalk-cdn.com/201...987149c2bd.jpg

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Haha.. really? Dallas? Did you drive it into the ocean at some point?

the car came from new york

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Aha! From the looks of the fasteners on that control arm, you rescued it in plenty of time.

I had a ton of soot and it even was shooting behind the car onto the ground in the garage as I warmed it up. That was with aftermarket UEL header, over pipe and OFT.
I had a member in here, Tor, adjust the tune and it went away significantly on the tail pipe and no more on the ground at all.

Ah I see, except from E85 being cheaper I wont notice a huge difference between E85 and 98 then.

It’s actually more like break even (at least in my area) cost wise due to the MPG drop with E85. For example I get about 250 miles on a tank of E85. I am completely stock with the exception of E85 and it’s a very noticeable increase in power. I don’t think he was saying it isn’t an improvement. It just isn’t as big of an improvement if you are going from high octane fuel to E85 vs lower octane fuel to E85. In my case I went from 93 to E85.

Gotcha, thanks for explaining. :lol: