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OBD2 vs durametric fuel trims and O2 sensor info

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3 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

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YOUR RESEARCHOBD2 vs durametric fuel trims and O2 sensor info

Leading reported evidence

Check crankcase pressure and it is 0.3 inh20 vacuum

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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.

Performed · outcome unconfirmed · Original poster

I've checked the crankcase pressure and it is 0.3 inH20 vacuum.

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info
Read full discussion summary

Leading evidence: 'Check crankcase pressure and it is 0.3 inh20 vacuum' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check crankcase pressure and it is 0.3 inh20 vacuum' (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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1 matching discussions · 3 captured posts examined · 0 partial discussions

Compare 4 other evidence results

Check fuel pressure

Performed · outcome unconfirmed

No successful repair reported for this finding.

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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

I have checked the fuel pressure, which is fine.

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Reset light and things will be fine

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

I reset the light and things will be fine for hundreds of miles.

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Check rubber bellows

Suggestion or failed attempt

No successful repair reported for this finding.

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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 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

Since you have a 99 check the rubber bellows under the AOS and the oil fill tube for big cracks...Also any AOS tubing..

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Replace vario-cam pads along

Suggestion or failed attempt

No successful repair reported for this finding.

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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 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 · Original poster

I recently took the engine out to replace Vario-Cam pads along with the other "while you're in there" stuff(AOS, clutch, water pump, thermostat...).

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info
Frequently discussed actions (6)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check crankcase pressure and it is 0.3 inh20 vacuum

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

I've checked the crankcase pressure and it is 0.3 inH20 vacuum.

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Check fuel pressure

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

I have checked the fuel pressure, which is fine.

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Check rubber bellows

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

Since you have a 99 check the rubber bellows under the AOS and the oil fill tube for big cracks...Also any AOS tubing..

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Replace vario-cam pads along

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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 · Original poster

I recently took the engine out to replace Vario-Cam pads along with the other "while you're in there" stuff(AOS, clutch, water pump, thermostat...).

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Reset light and things will be fine

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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

I reset the light and things will be fine for hundreds of miles.

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info

Run very lean

No successful repair reported for this finding.

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Reported fixes
0
Unsuccessful attempts
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Discussions
Read evidence and context
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

According to your Tra and FRA and manometer reading you are running very lean from a large crankcase leak../

Original post Read captured discussion
OBD2 vs durametric fuel trims and O2 sensor info
Coverage and how to read this overview

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.

3 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: 20261026T213932Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Hi. I have a 1999 C2. I recently took the engine out to replace Vario-Cam pads along with the other "while you're in there" stuff(AOS, clutch, water pump, thermostat...). Several times since then I have gotten a P1123 code. I reset the light and things will be fine for hundreds of miles. Then a repeat of the same. My OBD2 scanner gives me freeze frame info from the time the code was set. It shows that it was set at idle and -22 LTFT on both banks. It seems to be running this "high negative trim" at idle all of the time. I have researched the P1123 code and am aware of the usual suspects (MAF, leaking injector, high fuel pressure). I have checked the fuel pressure, which is fine. I also have durametric from which I have baseline data from before this issue began. What jumps out is that now my TRA on both banks is now .3, whereas it used to be slightly negative. I see in the WSM that this rise in TRA is also associated with removing the oil cap. I have a manometer and plan to get crankcase pressure readings later today. Perhaps my new AOS is defective? I find it noteworthy that the OBD2 LTFT seem to be cutting fuel while the TRA read from durametric seem to be adding fuel. Durametric doesn't show me the post cat o2 sensors or freeze frame data, which the OBD2 scanner shows. I would think all of the OBD2 data would be included in the Durametric data. Any insight would be appreciated. Thanks, Edward

POST 2 / ORIGINAL POSTEROriginal post

I've checked the crankcase pressure and it is 0.3 inH20 vacuum. I understand it should be around 5 inches.

POST 3Original post

According to your Tra and FRA and manometer reading you are running very lean from a large crankcase leak../ OBDII fuel trims are wonky and don't follow Porsche tester logic, so I rarely use them... Since you have a 99 check the rubber bellows under the AOS and the oil fill tube for big cracks...Also any AOS tubing.. Anything else will also leak oil as an indicator ( like the rubber cam plugs ect.)...

This is a source reference. Confirm exact model applicability in the original material.