17 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHStrange noise and smoke from the exhaust
Leading reported evidence
Check plugs-ok, borescope-ok, compression-ok
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
When tried to take it to the track recently, I noticed the smoke, checked the plugs-ok, borescope-ok, compression-ok.
Leading evidence: 'Check plugs-ok, borescope-ok, compression-ok' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'petroleum smell' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check aos this week' (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.
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
Installed new plugs and oem injectors on the Bank 1, the same thing.
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
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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.
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
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Performed · outcome unconfirmed
Since you have tested compression, tested leak down, scoped the cylinders , and all that has been found to be normal, then it is imperative to rule out the AOS System..
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
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Performed · outcome unconfirmed
Since you have tested compression, tested leak down, scoped the cylinders , and all that has been found to be normal, then it is imperative to rule out the AOS System..
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.
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Performed · outcome unconfirmed
Since you have tested compression, tested leak down, scoped the cylinders , and all that has been found to be normal, then it is imperative to rule out the AOS System..
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
Since you have tested compression, tested leak down, scoped the cylinders , and all that has been found to be normal, then it is imperative to rule out the AOS System..
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
petroleum smell
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
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Suspected cause
The smell is probably a petroleum smell from the smoke, gas and oil are both petroleum products...If it's a "raw gas Smell" then look for wet fuel leaks...
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.
17 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.
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Generation: 20261026T150451Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi 911 fellows, I have 996 engine on a Boxster and can't figure out the reason for the smoke with some fuel smell coming from the Bank 1 of the engine (2003 996). You can see/hear on the video(
You Tube
) also tapping sound from the exhaust
and it does feel like it is pushing fumes out more erratic and not as smooth as other side. Car has not been driven for about 2 years (race car). When tried to take it to the track recently, I noticed the smoke, checked the plugs-ok, borescope-ok, compression-ok.
Installed new plugs and oem injectors on the Bank 1, the same thing. Should I give the "Italian tune up" or may catch on fire?
Your help will be appreciated.
Could be Carbon build-up on top of the piston hitting the head making the noise, Carbon build-up possibly from a failing AOS and the resulting smoking from oil drenched into the exhaust/muffler...
I would suggest you do an AOS test.... Search the 996 archive for tools and proceeure..
Thanks for the reply. I did notice pretty good carbon build up on the piston on the cylinder #2 during bore scoping.. AOS has been changed few years ago. What about fuel smell from the right exhaust only?
It doesn't matter how OLD the AOS is..test it !! Don't gloss over the advice to test it...
The smell is probably a petroleum smell from the smoke, gas and oil are both petroleum products...If it's a "raw gas Smell" then look for wet fuel leaks...
Yes if the AOS is failing it can/will pool oil in the intake manifold and will spill out into a bank of cylinders or just one cylinder during turn or uphill or hard breaking, then the resulting smoke and smell from that side......
Test the AOS and if found to be faulty ( or even it is not ) upgrade to UAOS
www.ultimateaos.com
I hear you, will check for sure even thought AOS failure will make both pipes smoke and as I said the car has not been driven and just recently driven in a neighborhood to check everything for a track day. What I see online and few videos from Jake suggest sticky lifter. Will start elimination probable causes.
Thanks for your help.
The failing or just inadequate factory AOS System doesn't always make both sides smoke, it can just as easy make one side smoke as I said....
Since you have tested compression, tested leak down, scoped the cylinders , and all that has been found to be normal, then it is imperative to rule out the AOS System..
The pistons come very close to the heads on M96 engines and it doesn't take much carbon build-up to start tapping the head....I have seen RedLine SR-1 stop many a 3.4 engine knock/tapping..
I have used Driven DT40 to change the oil few weeks ago but will look in to SR-1 to see the benefits. I see, it is fuel additive, not oil. Seems like it is SI-1 Redline but had good reviews. I appreciate your help.
I would drive it first. Also, my humble opinion but stick to a normal oil with no additives. Liqui Molly is fine. I used DT40 for 30k miles and eventually suffered a cracked head, but am not saying they are related at all. Just finding things to blame lol.
2 years is a long time to sit, and these cars don't like to sit. Aos will show early signs and mask itself as a vacuum leak because the bellows tube blows out and leaks oil (is there oil on driveway ever, coming from around the marriage of the trans to block area (and on driver side?)? Another symptom is a loud hiss / sound of a lot of air from engine bay which I don't hear.
If you track your car, which it looks like you do (?) I would look at a Porsche Motorsport AOS for your M96 or fellow forum mate, Porschetech3's, ultimate AOS solution - a more durable and effective AOS solution than the Porsche Motorsports one.
Thanks for the advice. No oil spots or any other fluid leaks, engine looks as dry as it can be on a visual exam. Will try to get it out for a session at the local track and see what it does. Just was not sure if it can be fire hazard due to fuel smell.
I figured, car needs to be driven little longer than just 30 yards back and forth from the garage and alley. May be hard driving at least one lap will give me more clues.
Not street legal, so can't really take it on a hwy.
Curious - how many times do you do this? I try to avoid this as much as possible. I resort to pushing my car in and out of the garage instead of starting it. If I must start it for a short move, I try to run an errand. It�s not good to start an engine and not drive it to warm it up to operating temp.
