diagnostics: confirm ICP bleed-off via --crank (peak 376 psi)
Direct on-truck measurement with the verified 1446 ICP PID: peak cranking ICP 376 psi vs the ~500 psi firing threshold. FICM Main min 48.0 V (healthy), battery min 10.3 V (adequate). Diagnosis empirically confirmed: high-pressure oil bleeds off during cranking. 376 psi is "almost there" not zero, which fits a partial leak (IPR seat / oil rail O-rings / partial STC crack) rather than a fully blown STC fitting. - Capture the --crank output in crank-test-2026-06-30.txt - Add EMPIRICAL CONFIRMATION section to diagnostics README - Update handoff "resume at the truck" to lead with physical inspection (IPR -> STC -> oil rail O-rings), since the OBD-side diagnosis is done Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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@@ -38,6 +38,24 @@ No engine P-codes, no FICM codes, no injector codes, no CMP/CKP codes.
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injector drive, cam/crank sync, and the FICM-to-injector path are all
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good when the engine is turning at running RPM.
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## ⭐ EMPIRICAL CONFIRMATION (2026-06-30 crank test)
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Direct measurement with `--crank` and the verified `1446` ICP PID:
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**Peak cranking ICP = 376 psi** — below the ~500 psi firing threshold.
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Full output in [crank-test-2026-06-30.txt](crank-test-2026-06-30.txt).
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This is the smoking gun. Truck cannot generate enough ICP during cranking
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to open injectors → cannot fire on its own fuel → needs ether every time.
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Matches the symptom-set perfectly.
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Side data from the same test:
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- **FICM Main min: 48.0 V** — healthy, corroborates the meter.
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- **Battery min: 10.3 V** — sag but adequate.
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- 376 psi is "almost there" not zero → suggests a **partial** leak
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(IPR seat / oil rail O-rings / partial STC crack) rather than a
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fully blown STC fitting (which would typically show sub-100 psi).
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## ⭐ Key diagnostic finding: ether starts it every time
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Spraying starting fluid (ether) into the intake **gets the truck to fire,
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@@ -0,0 +1,36 @@
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2026-06-30 -- dedicated ICP-cranking test with the new --crank monitor.
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Command: python obd_reader.py --crank
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===== 6.0 CRANK MONITOR ===== 00:40 1.8 Hz frame 51
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crank the engine q=quit r=reset firing threshold = 500 psi
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ICP [---------------------------------|------] -- psi
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PEAK 376 psi BELOW 500 - keep cranking
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FICM Main -- (min 48.0) [DOC] Batt 11.8V (min 10.3) RPM --
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ICP trace (psi vs time, last 18 samples)
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600 |
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500 |--------------------------------------------------
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| #######
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| ##########
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| ##########
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| ##########
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| ##########
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| ###########
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+--------------------------------------------------
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Verdict line at exit:
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Peak ICP 376 psi -- did NOT reach 500 psi -- suspect high-pressure oil bleed-off.
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Headline:
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* Peak ICP reached 376 psi during cranking -- below the ~500 psi
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needed to physically open injectors. Truck CANNOT fire from cold
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start on its own. Matches the ether-only-starts symptom exactly.
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* FICM Main minimum 48.0 V -- healthy (corroborates the meter).
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* Battery minimum 10.3 V -- sag but adequate.
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* 376 psi is "almost there", not zero. HPOP is making real pressure,
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just losing it. Suggests a partial leak -- IPR seat / oil rail
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O-rings / partial STC fitting crack -- rather than a fully blown STC.
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+28
-15
@@ -71,6 +71,13 @@ The 6.0 needs, to fire: **good batteries → FICM ~48V → ICP ~500 psi → fuel
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bus problem. Verified PID set now in `obd_reader.py`; reasoning + sources
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in [pid-research.md](diagnostics/2026-06-29-no-start/pid-research.md).
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Added `--dash` (real-time gauges) and `--crank` (no-start monitor).
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- **2026-06-30 ICP crank test:** ran `--crank` on the truck — **peak ICP
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376 psi, below the 500 psi firing threshold**. Direct empirical
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confirmation of the high-pressure oil bleed hypothesis. FICM min 48.0 V
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(healthy), battery min 10.3 V (adequate). Output captured in
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[crank-test-2026-06-30.txt](diagnostics/2026-06-29-no-start/crank-test-2026-06-30.txt).
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Next: physical inspection (IPR valve first, then STC fitting, then
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oil rail O-rings).
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- Pushed to `git.jpaul.io/justin/ford-obd`, branch `main`.
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## To resume with Claude from the cab
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@@ -80,22 +87,28 @@ no-crank, hot vs. cold, what changed before it died, and FICM/ICP readings if yo
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## To resume at the truck (2026-06-30 state)
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The diagnosis stands: high-pressure oil (ICP) bleeds off during cranking;
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HPOP outruns the leak once running. The toolchain can now confirm this
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directly from the OBD port. Top actions, in order:
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The diagnosis is now **empirically confirmed** — `--crank` measured peak
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ICP 376 psi (need ~500 psi to fire). High-pressure oil bleeds off during
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cranking; HPOP outruns the leak once running. The 376 psi reading suggests
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a **partial** leak rather than a fully blown STC fitting. Physical
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inspection, cheap-and-easy first:
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1. **`python obd_reader.py --crank`** during a short crank. A healthy 6.0
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builds ~500+ psi ICP in 1–2 seconds. If ours stalls below 500 psi or
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builds very slowly, that confirms the bleed-off and is the smoking gun.
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2. **Probe the FICM PIDs that were outside the scan window** to validate
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the documented `09xx` family on this truck:
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- `python obd_reader.py --pid 09D0` (FICM Main, expect ~48V)
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- `--pid 09CF` (Logic, ~12V), `--pid 09CE` (Vehicle V), `--pid 09CD` (Sync)
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3. **Visual under the valve covers + STC fitting** — the likely physical
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source of the leak. STC fitting is the #1 6.0 culprit for this pattern.
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4. **Widen the brute scan** to round out the verified set —
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`python obd_reader.py --scan 0900-09FF --scan-log scan-09xx.txt` and
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`--scan 1600-16FF --scan-log scan-16xx.txt`.
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1. **Pull the IPR valve** (~15 min, ~$0). Bolted into the back of the
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HPOP, top-rear of engine under the turbo. Inspect screen for debris,
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pintle/seat for wear, O-rings for cuts. A leaky IPR seat causes
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exactly this "partial pressure" symptom.
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2. **STC fitting visual** — between the heads under the turbo. Look for
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wet/oily film at the fitting joint. Ford TSB; classic 6.0 wear item.
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3. **Pull valve covers** and inspect high-pressure oil rail O-rings on
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each head. Bigger job but common 6.0 leak path.
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4. (Once a repair is attempted, re-run `--crank` — peak ICP should jump
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to 500+ if the fix worked.)
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OBD-side follow-ups (lower priority now that we have the answer):
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- Probe the FICM 09xx family: `--pid 09D0` (Main, ~48V), `--pid 09CF`
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(Logic, ~12V), `--pid 09CE` (Vehicle V), `--pid 09CD` (Sync).
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- Widen brute scan: `--scan 0900-09FF --scan-log scan-09xx.txt`
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and `--scan 1600-16FF --scan-log scan-16xx.txt`.
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## Open follow-ups
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Detailed action list lives in
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