Aug 18, 2026

Day 8 — Updated Tune Validation (Cold Start)

1 log analyzed · 22.7 minutes logged · testing Mark_LSVTEC_base_map_2.msq on the car for the first time

Tune behaves as designed — one pre-existing hardware issue confirmed still present Full cold start to fully-warm idle, captured in one continuous 22.7-minute log. The idle ignition/AFR revisions from the pending tune review carried over cleanly: idle converges from an initial ~1300 RPM down to within roughly 15–60 RPM of the ~905 RPM target by the end of the log, coolant reached 91.7°C with no cooling issues, no knock was detected anywhere in the log, and a clean off-load rev to 5,848 RPM showed no stumble. The cranking voltage sag flagged in earlier sessions is still there — it took 3 crank attempts and ~21.5 seconds from key-on to a stable start, with VBatt sagging as low as 5.15 V during the failed attempts. That's a wiring/battery issue, not a tune issue.
22.7m
Logged duration
963±95
RPM, last 80s of idle
5,848
Peak RPM (off-load, 28% TPS)
3
Crank attempts to start

08Full-Session Trace: RPM, Coolant & Idle Target

Hover to inspect any point in the run — the tuner can use this to line up idle timing/AFR table cells against the coolant temperature and RPM that were actually seen at each stage of warm-up.

6000 RPM 4500 RPM 3000 RPM 1500 RPM 0 RPM 0:00 22:40
RPM Coolant temp (scaled 20–100°C over full height)
Decoded from C-Start-1.mlg (Aug 18 session), 20,409 records at ~15 Hz, downsampled to 301 points for display.

09Cranking Detail: Voltage Sag & Restart Attempts

Zoomed into the key-on→running window (t=10s to t=35s). This is the section to send to whoever is chasing the cranking-voltage issue — the sag pattern is unmistakable.

14V / 1600 RPM 10.5V / 1200 RPM 7V / 800 RPM 3.5V / 400 RPM t=10s t=35s
VBatt (0–14V) RPM (0–1600, scaled to same axis)
Three distinct crank attempts visible: RPM rises to 130–990 then drops back to 0 twice (t≈26.7s, t≈32.0s) before catching cleanly at t≈33.1s. Each attempt coincides with VBatt sagging to 5.1–7.6 V.

10Data For The Tuner

Concrete numbers pulled from this log for adjusting the base tune — all from the fully-warmed portion (CLT > 85°C) unless noted.

ChannelValue at warm idleNotes
Actual idle RPM (last 80s, TPS<3%)963 ± 95 RPMStill settling toward target; see convergence note below
Idle Target RPM906 RPMFrom the CLT-based target curve, not yet modified this session
Idle actuator position (IAC/ETB duty)40.0–42.6%Open-loop base duty, tight band
Ignition timing at idle13.3–15.7° (mean 13.9°)Interpolated value at idle RPM/MAP, not a raw table cell
Injector duty cycle at idle1.5–5.5% (mean 2.3%) 
VE at idle49.9–54.4% (mean 53.7%)Matches the "looks great" VE table finding from the tune review
MAP at idle≈27 kPa 
VBatt, running (post-start)14.2 V mean, 14.0–14.4 V rangeCharging system healthy once running
Coolant warm-up32.1°C → 91.7°C over 22.7 min80°C at 7.5 min, 90°C at 15.3 min
KnockNone detectedKnock level, count, and retard all read zero for the entire log
Wideband O2Not connectedwb1isValid = 0 for the whole log — AFR/lambda channels are not usable yet
Peak RPM reached5,848 @ t=1231.4sClutch-in/neutral rev to redline area, 28% TPS, Vehicle Speed = 0 throughout, clean decay back down
Idle closed-loop never engages in this log Idle: Closed loop active reads 0 for all 20,409 records, even though actual RPM sits below the closed-loop entry threshold (≈1207 RPM) for 99.7% of the idling samples — so the RPM-based entry condition is satisfied almost the entire time, yet closed loop never turns on. The open-loop CLT-based duty taper is still getting idle to converge (see trend below), so this isn't blocking anything today, but it's worth having the tuner check whatever other precondition (TPS-at-zero, "looks like running" state, etc.) is preventing entry, since closed-loop idle is the tool that will hold RPM tight against load once VTEC and A/C get added to the mix.
Idle convergence trend (2-minute buckets) Actual idle RPM decays steadily as the engine warms, from roughly 1265 RPM in the first 2 minutes down to 919 RPM by the last complete bucket (vs. a target that stays essentially flat at 905–955 RPM the whole time). By minute 22 the gap is down to about 14–60 RPM — open loop is doing the job on its own; it just takes the full warm-up cycle to get there on a cold start.

11Log-by-Log Breakdown

C-Start-1.mlg — Aug 18 sessionCRANK VOLTAGE SAG 5.15V

First on-car test of the pending tune (Mark_LSVTEC_base_map_2.msq). Full cold start through 91.7°C warm idle, plus a clean off-load rev to 5,848 RPM. Same cranking-voltage-sag pattern as prior sessions, now with 3 distinct restart attempts logged.

1360.5s
Duration
20409
Records
89.6–197.1°F
CLT range
5848.0
RPM max
963.6
Idle mean (tail)
94.8
Idle σ (tail)
5.15V
VBatt (crank min)
0%
Knock detected
3
Stall/restart events*
* On stall/restart counting Detected as RPM dropping to 0 for a sustained period followed by a subsequent rise during the cranking window — a reasonable proxy for restart events, not a precise fault classifier. Treat as directionally accurate, not exact.
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Day 7