Planet-9

991 compression test procedure, with PIWIS

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YOUR RESEARCH991 compression test procedure, with PIWIS

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Check compression

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Suggestion
, while cranking the engine to check the compression?
Original post Read captured discussion
991 compression test procedure, with PIWIS

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Leading evidence: 'Check compression' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check compression' (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.

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Run into the picoscope issue

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Suggestion
It's smart to get those baseline compression numbers before hitting the track, and I see you've run into the picoscope issue with PIWIS.
Original post Read captured discussion
991 compression test procedure, with PIWIS

Test initiation dialog, however i do not own a picoscope

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Suggestion
and have found the compression test initiation dialog, however I do not own a picoscope which prevents the procedure from running.
Original post Read captured discussion
991 compression test procedure, with PIWIS

Test on 991 and was wondering if anyone knew where

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Suggestion
I have not been able to find any write-up on how to perform a compression test on 991 and was wondering if anyone knew where to find this procedure.
Original post Read captured discussion
991 compression test procedure, with PIWIS

Frequently discussed actions (4)

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Check compression

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
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Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

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Suggestion
, while cranking the engine to check the compression?
Original post Read captured discussion
991 compression test procedure, with PIWIS

Run into the picoscope issue

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
It's smart to get those baseline compression numbers before hitting the track, and I see you've run into the picoscope issue with PIWIS.
Original post Read captured discussion
991 compression test procedure, with PIWIS

Test initiation dialog, however i do not own a picoscope

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
and have found the compression test initiation dialog, however I do not own a picoscope which prevents the procedure from running.
Original post Read captured discussion
991 compression test procedure, with PIWIS

Test on 991 and was wondering if anyone knew where

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
I have not been able to find any write-up on how to perform a compression test on 991 and was wondering if anyone knew where to find this procedure.
Original post Read captured discussion
991 compression test procedure, with PIWIS

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4 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

Planet-9: 1 discussions

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Generation: 20261026T191851Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1Original post

Hi, new to the forums here. I'm getting ready for trackday season and would like to perform a compression and leakdown test to establish baselines prior to wringing it out on track. I'm somewhat familiar with PIWIS and have found the compression test initiation dialog, however I do not own a picoscope which prevents the procedure from running. I am hoping to use an analog compression gauge while the engine cranks, while not injecting fuel. I am extremely hesitant to manually crank the engine without the ECU correctly managing HPFP and injector disablement. I'm also hesitant to disable LPFP, potentially starving HPFP of fuel and lubricity if only for a short time. I have not been able to find any write-up on how to perform a compression test on 991 and was wondering if anyone knew where to find this procedure.

POST 2Original post

Can you remove the fuse for the fuel pump , while cranking the engine to check the compression?

POST 3Original post

Hey @zero32nds , welcome to the forums! It's smart to get those baseline compression numbers before hitting the track, and I see you've run into the picoscope issue with PIWIS. When you try to run the test, does it give a specific error message or just refuse to start? Sharing the exact message might help someone here suggest a workaround.

POST 4Original post

As far as I understand, the fuse only disables the low pressure fuel pump . HPFP is driven mechanically and internal regulation controlled directly by the PCM . When cranking, the injectors will still attempt to fire, delivering whatever residual fuel is present in the high pressure side. From what I understand there is risk of damage / cavitation to the HPFP due to lack of flow at the low pressure side, similar to running out of gas. HPFP’s typically do not enjoy operating in this state.

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