Black Soot Coming From Exhaust

[R33-RB26DETT]

When i let my car warm up in the morning, i let it sit there for a about 3 minutes.

But i've noticed that sometimes there is quite a lot of black oily soot that comes out onto the asphalt from my exhaust.

Is this normal? I'm hoping it's just because my car is running really rich?

I had my car compression tested a couple months ago and all cylinders were perfect so I imagine that this would be quite normal for a car running rich right?

[MrStabby]

When i let my car warm up in the morning, i let it sit there for a about 3 minutes.

FWIW Its better for the motor if you drive smoothly (no boosting, rpm below 3000) to warm it up.

But i've noticed that sometimes there is quite a lot of black oily soot that comes out onto the asphalt from my exhaust.

Nothing to worry about. If you see a lot of black smoke when you're boosting then you should probably get it tuned.

[R33-RB26DETT]

Thanks Adam, I suspected as much, but thanks for confirming it's nothing to worry about.

Yeah i've heard that just driving it below 2500 - 3000 rpm and off boost is better - maybe i'll give it a shot. In the morning though, i think that i'll still let it sit there fore at least 30 seconds before i drive off.

[maclarenf1]

Exact same thing happen in mine as well

also Comp tested, leak down and engine was told to be very healthy

still running the Jap tune, time for a slightly less rich tune maybe

[Dani Boi]

I also get the black soot you speak of, only generally happens the first time I start it up in the morning. It only spurts out for a second then doesn't do it after that.

[Bunta]

condensation occurs in the exhaust when the car sits, it mixes with the soot that is naturally in there. First start of the day blows most of it out, our cars are more prone due to bigger exhausts that allow moisture in there easier. If it happens when warm and under acceleration then it is proably too rich

[AngryRB]

When i let my car warm up in the morning, i let it sit there for a about 3 minutes.

But i've noticed that sometimes there is quite a lot of black oily soot that comes out onto the asphalt from my exhaust.

Is this normal? I'm hoping it's just because my car is running really rich?

I had my car compression tested a couple months ago and all cylinders were perfect so I imagine that this would be quite normal for a car running rich right?

The soot would be from a rich mixture wouldnt it?? like from the previous days drive, where you might have squirted it and the car ran rich a few times then in the morning the condensation is washing the soot out , dripping onto the asphalt.. correct me if im wrong..

i give it 5mins idle, and baby it for another 15mins

[StevenCJR31]

The soot would be from a rich mixture wouldnt it?? like from the previous days drive, where you might have squirted it and the car ran rich a few times then in the morning the condensation is washing the soot out , dripping onto the asphalt.. correct me if im wrong..

i give it 5mins idle, and baby it for another 15mins

it could be from a rich mixture depending on the condition of your O2 sensor or how well your cat is/isnt working-either way it sounds like you dont have much to worry about

[R33-RB26DETT]

it could be from a rich mixture depending on the condition of your O2 sensor or how well your cat is/isnt working-either way it sounds like you dont have much to worry about

Thanks, yeah i'm pretty sure that it must be a rich tune now.

It's still running the Jap tune on the Apexi FC from before i imported it to Aus.

Also, it's running a high flow metal cat, not sure if that would somehow contribute to the situation though.

[mad082]

The soot would be from a rich mixture wouldnt it?? like from the previous days drive, where you might have squirted it and the car ran rich a few times then in the morning the condensation is washing the soot out , dripping onto the asphalt.. correct me if im wrong..

i give it 5mins idle, and baby it for another 15mins

idling for 5 mins is a waste of fuel, and is probably doing more damage than good. the reason being that at idle the car takes longer to warm up than when driving sedately, plus the fact that only the engine oil is heating up and not the gearbox or diff oil. also some people say that at idle you don't get quite as good combustion so you have the bores being washed down by fuel a bit and this reduces the ability of the oil to lubricate. generally speaking, 10 mins of sedate driving should be enough (15 in winter) as long as your thermostat is working properly as the coolant temp should be approaching operating temp within a few minutes.

as for the soot on the ground, as someone said above, it is just condensation mixing with soot.

[AngryRB]

idling for 5 mins is a waste of fuel, and is probably doing more damage than good. the reason being that at idle the car takes longer to warm up than when driving sedately, plus the fact that only the engine oil is heating up and not the gearbox or diff oil. also some people say that at idle you don't get quite as good combustion so you have the bores being washed down by fuel a bit and this reduces the ability of the oil to lubricate. generally speaking, 10 mins of sedate driving should be enough (15 in winter) as long as your thermostat is working properly as the coolant temp should be approaching operating temp within a few minutes.

as for the soot on the ground, as someone said above, it is just condensation mixing with soot.

i see your point, and people can do whatever they like, but ive done the drive off straight away like your talking about, when i do that the engine feels very tight like its full of friction, and the gearbox will crunch second gear too,

I have a tuned power fc which shows coolant temp of 50degrees or more by 5mins, the gearbox also changes sweetly so it must be warming up some what too

as for fuel washing cylinders, i use a good dose of lucus upper cylinder lube in my fuel, and im not sure if 5mins stone cold on 2000-2500 would be better than 5mins to warm up first, but its all speculation unless you can prove stuff scientifically.. until then ill stick with my padantic method, lol...

[MrStabby]

i see your point, and people can do whatever they like, but ive done the drive off straight away like your talking about, when i do that the engine feels very tight like its full of friction, and the gearbox will crunch second gear too,

What engine oil and gearbox oil do you use? I believe thicker oils cause more damage at start up (but its still an almost insignificant amount). FWIW full synth oil is more consistent across temperature ranges than dino.

I have a tuned power fc which shows coolant temp of 50degrees or more by 5mins,

I don't think coolant temperature is a good indicator. My coolant temperature gets up fast, the oil takes a lot longer. I keep things sedate until my oil's at 70 degrees on the gauge, which is where it stays during normal driving. So full temp.

Re: your response to Mad's comment on fuel washing cylinders - if you want to know for sure, get your oil tested. One of the things they test is fuel contamination. Mad has the theory correct, but the effect may not be significant in your case.

[AngryRB]

What engine oil and gearbox oil do you use? I believe thicker oils cause more damage at start up (but its still an almost insignificant amount). FWIW full synth oil is more consistent across temperature ranges than dino.

I use MOBIL 1 GOLD for engine 0-40, gearbox has nulon semi with a litre of mobil Gold to make it light, most box's are a bit worn though hey

I don't think coolant temperature is a good indicator. My coolant temperature gets up fast, the oil takes a lot longer. I keep things sedate until my oil's at 70 degrees on the gauge, which is where it stays during normal driving. So full temp.

Hmm, think ill get an oil guage, sounds like a useful gauge to have

Re: your response to Mad's comment on fuel washing cylinders - if you want to know for sure, get your oil tested. One of the things they test is fuel contamination. Mad has the theory correct, but the effect may not be significant in your case.

yeah it was a good point, i agree with that you both and also they use lucus on the drag cars too, bit of insurance .

apologies for getting this convo off topic of the soot issues etc...

[mystery_kid]

I keep things sedate until my oil's at 70 degrees on the gauge, which is where it stays during normal driving. So full temp.

do you have an oil cooler or something?

that seems very cold for oil, the oil in my old r32 and my r34 now both run at 92ºC at full temp.....

[mad082]

i see your point, and people can do whatever they like, but ive done the drive off straight away like your talking about, when i do that the engine feels very tight like its full of friction, and the gearbox will crunch second gear too,

I have a tuned power fc which shows coolant temp of 50degrees or more by 5mins, the gearbox also changes sweetly so it must be warming up some what too

as for fuel washing cylinders, i use a good dose of lucus upper cylinder lube in my fuel, and im not sure if 5mins stone cold on 2000-2500 would be better than 5mins to warm up first, but its all speculation unless you can prove stuff scientifically.. until then ill stick with my padantic method, lol...

if you were to drive off after about a minute of idling you'd probably find that you would get to over 50 degrees after about a minute or two of driving (so probably about 2 mins faster than by letting it idle).

[MrStabby]

do you have an oil cooler or something?

that seems very cold for oil, the oil in my old r32 and my r34 now both run at 92ºC at full temp.....

I do, an HKS kit, but its thermostated IIRC. That's just what the gauge says, so no idea if the calibration is off, but the needle location is consistent. It goes up with track work, but i back off once it reaches 110 (it would keep going up).

[MrStabby]

I use MOBIL 1 GOLD for engine 0-40, gearbox has nulon semi with a litre of mobil Gold to make it light, most box's are a bit worn though hey

Hang on - did you say you are thinning your gearbox oil with engine oil??

I'd say that's a very bad idea....

[Dani Boi]

lol

[AngryRB]

Hang on - did you say you are thinning your gearbox oil with engine oil??

I'd say that's a very bad idea....

yeah well its either that or crunch some gears or go get the gearbox rebuilt, so i choose option A

Im pretty sure a gearbox shop said i could do that and get away with it, when i had a mazda the dealer said in severe cases of gearbox trouble, you can even use automatic gearbox in a manual, and that stuff is like water... which ive done and it fixed up the crunching second gear,.... but i stress its a last resort and not recommended of course..

But the proof is in the driving isnt it??? when i bought my car i was crunching 2nd when cold, and 3rd was kind of jarring like it didnt want to go in, and now i have none of those problems so obviously it cant be that bad..

[AngryRB]

if you were to drive off after about a minute of idling you'd probably find that you would get to over 50 degrees after about a minute or two of driving (so probably about 2 mins faster than by letting it idle).

good point , but by the time i get the thing out the shed and out the front gate, its close to 5mins, lol..

can just imagine what the neighbours think, booooarrrr booarrrrr, hahah, soak it up people its an annoying rb,