9 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHSooty exhaust tips, troubleshooting help needed
Leading reported evidence
Replace 3 coils
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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 performed work without a confirmed outcome
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.
Performed · outcome unconfirmed
I recently replaced the 3 coils on the passenger side, all 4 O2 sensors and new air filter - did not improve / reduce the soot.
Leading evidence: 'Replace 3 coils' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'fuel' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check voltage' (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 performed work without a confirmed outcome
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.
Performed · outcome unconfirmed
Car has 66,000 miles, plugs were replaced at 59,000.
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 performed work without a confirmed outcome
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.
Replace last month (passenger side this coming sunday)
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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 performed work without a confirmed outcome
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.
Performed · outcome unconfirmed · Original poster
driver side plugs & coils replaced last month (passenger side this coming Sunday)
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 performed work without a confirmed outcome
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.
Performed · outcome unconfirmed · Original poster
Plugs and coils for that bank were replaced 30days ago.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
fuel
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
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.
Suspected cause
Soot is caused by fuel, so it could be overfilling on one side of the engine, most likely caused by a faulty coil pack maybe not igniting the spark as it should.
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.
9 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: 20261026T133652Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have a 99 C2 with 100125 on the clock and recently the passenger side exhaust is accumulating more soot than normal and much more than the driver side exhaust tip. No CEL or codes (indy verified) and no noticeable decrease in drive quality. With no "smoking gun" I am enlisting the help of fellow rennlister on potential solution/troubleshoot ideas and solutions.
Notes:
Oil consumption has not increased
AOS replaced the last 24 months
driver side plugs & coils replaced last month (passenger side this coming Sunday)
Thanks in advance from your time and Happy New Year
Soot is caused by fuel, so it could be overfilling on one side of the engine, most likely caused by a faulty coil pack maybe not igniting the spark as it should.
I'd start with that, coil packs and spark plugs are cheap to replace.
Keith
Plugs and coils for that bank were replaced 30days ago. I'm wondering if one of the O2sensors for that side is going bad, but with no codes it's anyone's guess
Bad coils or a failing O2 sensor will trigger the CEL. Don't start throwing parts at it or it will get really expensive fast. Its colder now days, the engine runs richer for longer, probably that's the reason for the carbon.
With no drivability issues, no CEL, no increase in gas consumption, no signs of anything wrong, I'd put the extra soot down as just an artifact of the climate (mainly colder) and how the car is being driven.
Do not discount this. I note the passenger side is the sooty side. If the weather has been wet where you are and you have been driving the car in the rain water splash can cool the exhaust and the converter and effect to some extent its performance.
Remember there is one and in some MY's two converters between the combustion chambers and the exhaust tips and the appearance of the exhaust tips can be more a reflection of how the converter or converters are doing than early warning signs of engine trouble.
If the soot accumulation is not within the normal range, the converter on the side with more soot at the exhaust tip may be getting weak, but not yet weak enough to trigger a CEL and error code.
With an OBD2 scan tool with the ability to view say the #2 O2 sensor readings simultaneously you might view them and see if there are any differences. The weak converter, if one is weak, should have the voltage level of the #2 O2 sensor lower than the other side's reading. The reading won't be steady lower just once in a while lower. If it was too severe a drop or too persistent a drop the CEL would be on.
My '99 C2 has been doing the same thing for about the last 1,000 miles. Driver's side exhaust is sooty, so it's coming from the passenger side bank. Started sometime during the summer. Car has 66,000 miles, plugs were replaced at 59,000. I pulled the 3 plugs and all 3 looked dirty. Gas mileage and performance have not changed. Threw a little money at it. I recently replaced the 3 coils on the passenger side, all 4 O2 sensors and new air filter - did not improve / reduce the soot. I'll check the voltage on both #2 O2 sensors and see how they compare to each other.
Kevin
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