18 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBlack dust on rear bumper
Reported or suspected cause
unburnt hydrocarbons
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Leading evidence: 'unburnt hydrocarbons' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'unburnt hydrocarbons' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Run overly rich the cel would be' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
If the engine was running overly rich the CEL would be on.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
18 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T144035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Im having a lot of black dust on my rear bumper, more on the driver side, can this be burned coolant (car smell � lot like i said in another thread) or maybe its just normal?
Im pretty sure its not my brakes, there is not dust on my wheels.
i overfilled her last time, that could explain the soot because thats the first time this summer ive seen that... Also its getting colder on colder here in Qu�bec, but i think that with cold air there is less chance of running rich, again im not an expert, got the car for only 2-3 month, previous was a 350z which is a totally different car...
sorry for my poor english, im a french Canadian
Hi Richard. I get the same thing. I wash the car about once a week but use it pretty much every day. Always see a bit of that on the rear bumper when washing it. I suspect unburnt hydrocarbons. Do you have a stock exhaust? Any ECU tune?
I get it too. May also be tire rubber, brake material or just plain old road grime. I never really considered exhaust, as mine is usually all the way from the wheel arc back.
Not coolant. You'd smell the odor of antifreeze if it were.
If you overfilled the engine with oil that's not good, but plays no role in the amount of soot. For every gallon of gasoline the engine burns it produces around 19lbs of carbon, mostly in the form of CO2 but some in the form of soot. A bit extra oil in the engine and a bit extra oil consumption possibly arising from this will not affect the engine's carbon output to any significant degree.
If the engine was running overly rich the CEL would be on.
So, the bulk of that is just tire dust. Normal.
The back of my Turbo collects a lot of this black tire dust in no time. The roads here haven't been rained on in months and the tire dust is thick. (One contributing factor why the roads are so treacherously slick with the first rain.)
An incomplete burn CAN cause the car to sooty; however, when the humidity is low enough, just driving the car produces an electrostatic charge which can cause dust and other very small debris to be attracted to the car.
