ARC-TUNING — Power Enrichment

1.1 PE EQ Ratio vs RPM 📍 LOCATE

HPTEngine → Fuel Control → Power Enrich → Power Enrich EQ Ratio

EFILive[0411] Fuel → Power Enrich → {B0107} EQ Ratio vs RPM

TunerPro XDFPE EQ Ratio vs RPM (Snoman002 0411 XDF)

LS1 EditFuel → Power Enrichment → PE Multiplier vs RPM

⚠ Attention needed

The primary PE table. Commands AFR via lambda multiplier (EQ ratio × stoich = commanded AFR). Stock '99 LS1 cal targets 1.25 (11.74 AFR) across most of the curve — overly rich for power. The classic LS peak-power target is 12.6–12.8 AFR, which is EQ 1.148–1.166. Current tune is still at near-stock values.

Your is way too rich at the top end. Stock GM is paranoid — burns extra fuel as a safety margin instead of going for power. Scarecrow moves you into the where most builds make their best numbers.

CURRENT In tune file

RPM	1500	2000	2500	3000	3500	4000	4500	5000	5500	6000	6500
EQ	1.20	1.23	1.25	1.25	1.25	1.25	1.25	1.25	1.25	1.25	1.25
AFR→	12.2	11.9	11.7	11.7	11.7	11.7	11.7	11.7	11.7	11.7	11.7

Stock factory values for '99 LS1. Conservative — protects emissions hardware that isn't on this car anymore.

✦ SCARECROW SUGGESTS Optimized for build

RPM	1500	2000	2500	3000	3500	4000	4500	5000	5500	6000	6500
EQ	1.10	1.13	1.16	1.17	1.17	1.16	1.16	1.17	1.18	1.19	1.21
AFR→	13.4	13.0	12.6	12.5	12.5	12.7	12.7	12.5	12.4	12.3	12.1

Classic shape: rich into peak torque (12.5 @ 3000), lean slightly to peak power (12.7 @ 4000), richen back up past peak power for piston cooling.

Δ DIFF Current → Scarecrow

RPM	1500	2000	2500	3000	3500	4000	4500	5000	5500	6000	6500
ΔEQ	-.10	-.10	-.09	-.08	-.08	-.09	-.09	-.08	-.07	-.06	-.04
ΔAFR	+1.2	+1.1	+0.9	+0.8	+0.8	+1.0	+1.0	+0.8	+0.7	+0.6	+0.4

All cells leaner. Largest changes at low-mid RPM where stock was pulling far too much fuel.

✦ SCARECROW REASONING CONFIDENCE: HIGH

Stock '99 cal at 1.25 EQ across the upper RPM range commands ~11.7 AFR — that's well past peak-power AFR for any normally aspirated LS and is leaving real horsepower on the table due to misfire-margin over-fueling. The shape I'm proposing follows the universally documented LS pattern:

Rich into peak torque (12.5 AFR @ 3000–3500 RPM): peak cylinder pressure → peak heat → most fuel needed for charge cooling.
Lean to peak power (12.7 AFR @ 4000–4500): well-known LS HP/AFR curve sweet spot. Some heads-cammed builds run 13.0 here — start at 12.7 and verify on dyno.
Richen back up past peak power (12.1 AFR @ 6500): piston/exhaust valve thermal protection. Catless = no cat to worry about scorching, but the engine itself still needs the fuel for cooling.

What I'm NOT certain about: the exact peak-power AFR for your specific cam/heads combo. 12.7 is community consensus for stock-ish LS2; if you have aggressive heads work, it could move to 12.9–13.1. Verify on dyno or in a wideband datalog before locking these numbers in.

Stock GM is set up to never hurt your engine — even if it costs you 30+ HP. Scarecrow's curve still keeps things safe, just not absurdly rich.

Run rich at the — that's where it's hottest, you want extra fuel cooling things down
Lean a notch at — that's where the magic AFR lives
Richen back up — keeps pistons cool at high revs

Don't trust these blind. Most builds find their sweet spot in the ; aggressive heads-cammed builds can run a touch leaner. on the road or dyno before you call it final.

11 cells changed · avg -0.082 EQ (avg +0.86 AFR)

AFR curve overlay — current (red) vs Scarecrow suggested (purple)

EQ / AFR heat scale 1.10 · 13.4 lean → 1.15 · 12.8 optimal → 1.18 · 12.4 mild rich → 1.21 · 12.1 rich → 1.25 · 11.7 over-rich Same scale used in 1.4 Base AFR vs ECT

1.2 PE Enable Conditions — All Four Must Be True 📍 LOCATE

HPTEngine → Fuel Control → Power Enrich → Enable

EFILive[0411] Fuel → Power Enrich → Enable Conditions

TunerPro XDFPE Enable {TPS, RPM, MAP, Min Torque}

🚨 LS2 swap critical fix

The PCM checks all four enables every loop and only activates PE if every condition is true. Most "PE never engages" forum threads are caused by one enable silently blocking the other three. The Min Torque enable is the silent killer on swap cars because the PCM's torque model is calibrated for the original 5.7L.

Four have to be true at the same time before kicks in. On your , one of them — — silently blocks the show. Scarecrow's fix matches your build.

LIVE @ 4250 RPM, 88% TPS ✓ TPS 88% > 60% req ✓ RPM 4250 > 1500 req ✓ MAP 96 > 80 kPa req ✗ Min Torque 142 < 168 req PE: NOT ACTIVE

TPS Enable Hot (avg)

23%

stock '99 cal

✦ Scarecrow: TPS Enable Hot (avg)

60%

flat across all RPM

Δ Diff

+37%

PE only at deliberate WOT

PE Delay RPM

2400rpm

auto-trans formula

✦ Scarecrow: PE Delay RPM

1500rpm

T56 launch RPM − 500

Δ Diff

-900rpm

earlier engagement

PE Min MAP

68kPa

stock

✦ Scarecrow: PE Min MAP

80kPa

NA-appropriate

Δ Diff

+12kPa

no PE at part-throttle

PE Min Torque (the silent one)

240N·m

stock — calibrated for 5.7L

⚠ PCM torque model under-reports actual torque on your LS2

✦ Scarecrow: PE Min Torque

168N·m

stock × 0.70 (LS2 swap)

Δ Diff

-72N·m

PE will actually engage now

✦ SCARECROW REASONING CONFIDENCE: HIGH

The live status panel above is showing exactly the swap-car PE problem in action — all three obvious enables (TPS, RPM, MAP) are met but Min Torque is blocking PE. This is because the PCM's internal torque model assumes a 5.7L pulling X kPa MAP at Y RPM produces Z torque; your 6.0L produces more, but the PCM's reported torque value (used for the enable check) is computed from its airmass model which is calibrated for the smaller engine.

Min Torque dropped to 168 N·m (×0.70 of stock): compensates for the displacement-driven torque-model offset.
TPS Enable raised to 60% flat: race-car logic — you only want PE on intentional throttle inputs, not on aggressive part-throttle. Stock 23% causes accidental PE during spirited cruising.
Delay RPM to 1500: T56 launch around 2000 RPM, minus 500 margin. Documented manual-trans rule.
Min MAP to 80 kPa: NA-engine appropriate. Below 80 kPa you're not at WOT, you don't want PE.

The live panel above is showing your problem in action — TPS, RPM, and MAP are all good, but the PCM thinks engine load is too low to . The computer thinks you've got an LS1 in there, not an LS2 — the airmass math is calibrated for the smaller engine.

Three of the four threshold changes are simple race-car tightening — only let PE fire on deliberate WOT, not on aggressive cruising. The fourth — — gets dialed back 30% to compensate for your . After this, PE actually fires at WOT instead of getting silently blocked.

4 scalars changed · fixes "PE not engaging" issue

!

Pattern detected in your last datalog (4 min ago)

At 17:42:08 in your last log, RPM hit 4250 / TPS 88% / MAP 96kPa — three of four PE enables met — but PE EQ remained at 1.000 and AFR drifted lean to 14.2 under load. This is the Min Torque enable blocking PE pattern Scarecrow recognizes on LS swap configurations. Apply the suggested Min Torque value above and re-log.

1.3 Enrichment Rate (PE Ramp-In) 📍 LOCATE

HPTEngine → Fuel Control → Power Enrich → Enrichment Rate

EFILive[0411] Fuel → Power Enrich → {B0108} PE Ramp Rate

✓ Conservative default

Controls how fast PE ramps in once enables are met. A common cause of misfires at PE engagement on cammed / boosted LS engines — too high a rate dumps fuel as a "vertical wall" all at once.

Controls how fast the extra fuel arrives once kicks in. Stock is a smooth half-second ramp. Going crazy on this number is a known cause of on cammed and boosted LS engines.

Current Enrichment Rate

0.0200

stock — smooth ramp ~0.5s

✦ Scarecrow: Enrichment Rate

0.0200

no change recommended

Pro tip available

Set to 1.0 for tip-in KR

if knock at WOT entry

✦ SCARECROW REASONING CONFIDENCE: MEDIUM

Keeping rate at 0.0200 (stock smooth ramp) for now. You don't have any reported tip-in knock retard in your last log, so there's no reason to change it. If you start seeing KR right at WOT entry, the documented LS1 community fix is to set this to 1.0, which makes PE arrive instantly and floods cylinders with cooling fuel before knock can develop.

Don't go above 1.0 — values like 1.5–2.0 cause the misfire pattern documented in the HP Academy SC LS1 thread (forum consensus calls 2.0 "~100x what GM uses").

Leaving this alone for now. Your last datalog didn't show any , so the stock smooth ramp is fine.

If you start hearing knock the moment you punch the throttle, the community fix is set this to 1.0 — that makes PE arrive instantly, flooding the cylinders with cooling fuel before knock can develop.

Don't go above 1.0. Values like 1.5–2.0 cause the opposite problem (the supercharged LS1 misfire thread is the textbook case — fuel arrives as a wall and drowns the cylinders).

No change · flagged for monitoring

1.4 Base PE AFR vs ECT 📍 LOCATE

HPTEngine → Fuel Control → Power Enrich → Base PE AFR vs ECT

EFILive[0411] Fuel → Power Enrich → {B0109} Base AFR vs ECT

⚠ Texas summer adjustment

Adjusts the PE base AFR by coolant temperature. The PE EQ Ratio table builds on top of this. Critical for hot-climate race use — don't lean out at high ECT or you'll cook pistons in 105°F Texas summer.

Adjusts your by . Stock leans it out when things get hot — wrong call for a Texas race car. Scarecrow does the opposite: stays consistent through normal range and gets richer when really hot, for .

CURRENTstock

°F	140	160	180	200	220	240
AFR	12.5	12.5	12.6	12.8	13.0	13.2

Stock leans out at high ECT — assumes you'll back off when hot. Wrong assumption for a race car.

✦ SCARECROW SUGGESTSTexas race-spec

°F	140	160	180	200	220	240
AFR	12.5	12.5	12.5	12.5	12.5	12.4

Flat across normal operating temp. Slightly RICHER at 240°F (heat soak protection), not leaner.

Δ DIFFCurrent → Scarecrow

°F	140	160	180	200	220	240
ΔAFR	0.0	0.0	-0.1	-0.3	-0.5	-0.8

Heat-soak protection: 240°F is now 0.8 AFR richer than stock instead of 0.7 leaner.

✦ SCARECROW REASONING CONFIDENCE: HIGH

GM's logic for leaning the table at high ECT was: "if it's that hot, the driver should back off, so we'll save fuel." That logic does not apply to a Texas race car at WOT during a 30-minute heat-soak track session. The engine is going to see 220–240°F coolant; you want more charge cooling there, not less.

My suggestion holds 12.5 AFR flat across the normal operating range and adds 0.1 AFR of richening at 240°F. This is consistent with the principle that peak heat → peak fuel demand for cooling.

GM's thinking: "if it's getting hot, the driver should back off, so let's save a little fuel." That's a fine assumption for a Buick LeSabre. Total disaster for a Texas race car that's gonna see 220–240°F coolant during a 30-minute track session — the engine wants more cooling fuel under heat soak, not less.

Scarecrow keeps fueling flat through your normal range and adds 0.1 AFR of at 240°F. Same principle as section 1.1: peak heat needs peak fuel for cooling.

4 cells changed · max -0.8 AFR @ 240°F

1.5 Add Fuel vs RPM (with PE Timer axis)PRO 📍 LOCATE

HPTEngine → Fuel Control → Power Enrich → PE Add/Sub → Add vs RPM

EFILive[0411] Fuel → Power Enrich → {B0110} Add vs RPM/Timer

⚙ Pro mode only

Adds incremental fuel as time-in-PE accumulates. Useful for sustained WOT (drag/road race) where the engine soaks heat and needs progressive enrichment. Most street tuners ignore this table. If you do road-course events, this is where you eke out the last 5–10HP of consistency on lap 12.

Adds a touch of extra fuel the longer you stay at WOT. Useful for where the engine builds up heat — drag racing or road course laps. Most street guys ignore this. If you run track events, this is where you save your engine on lap 12.

CURRENTstock — all zeros

RPM \ Time	0s	2s	5s	10s	20s
3000	0.00	0.00	0.00	0.00	0.00
4500	0.00	0.00	0.00	0.00	0.00
6000	0.00	0.00	0.00	0.00	0.00

Disabled out of the box. GM doesn't use it on most factory cals.

✦ SCARECROW SUGGESTSheat-soak adder

RPM \ Time	2s	5s	10s	20s
3000	0.00	0.01	0.02	0.03
4500	0.01	0.02	0.03	0.04
6000	0.01	0.03	0.04	0.05

Progressive +0.05 EQ (~0.5 AFR richer) by 20s of WOT at 6000 RPM. Track-day insurance.

Δ DIFFCurrent → Scarecrow

RPM \ Time	2s	5s	10s	20s
3000	0	+.01	+.02	+.03
4500	+.01	+.02	+.03	+.04
6000	+.01	+.03	+.04	+.05

Maximum impact at high RPM, sustained WOT.

✦ SCARECROW REASONING CONFIDENCE: MEDIUM

This is a pro-mode optimization for sustained WOT use (drag pulls beyond 5 seconds, road course straights, long pulls on a chassis dyno). The base PE table assumes cylinder temps stabilize quickly; in reality, on a sustained pull the heads soak heat and combustion temps creep up, so a small progressive enrichment helps protect against late-pull knock and exhaust valve thermal damage.

Why "medium" confidence: the exact magnitude is build-dependent. These values are conservative starting points; some race builds run 2–3× this much progressive enrichment. If you don't do sustained-WOT events, you can leave this table at zero (stock) with no penalty. If you do, monitor EGT during long pulls and verify your exhaust valves stay below 1500°F.

Track-day insurance. The base PE table assumes things stabilize quickly — but on a sustained pull, the heads soak heat and combustion temps creep up. A small progressive richening helps protect against late-pull and exhaust valve thermal damage.

Why only "medium" confidence? The right amount is build-dependent. These values are conservative starting points; some race builds run 2–3× this much. If you don't do sustained-WOT events, leave this at zero with zero penalty. If you do, watch during long pulls.

15 cells, conservative track-day adder

1.6 Cat Overtemp Enrichment ModelPRO 📍 LOCATE

HPTEngine → Fuel Control → Cat OT Enable + Cat OT Enrichment Adders

EFILive[0411] Fuel → Cat Protection → {C0501} Cat OT Model

⚙ Catless build optimization

The PCM has a hidden "cat overtemp protection" model that adds enrichment when it predicts catalyst temp is too high. On your catless car, this model is making fueling decisions based on a catalyst that doesn't exist. This is a tuning fix (model running on phantom hardware), separate from emissions monitor disables.

The PCM has a hidden that dumps extra fuel when it thinks the catalyst is too hot. You don't have a catalyst. The model is making fueling decisions based on on your car. This is a tuning fix — separate from monitor disables, which Scarecrow doesn't write (see scope card below).

Cat OT Enable

TRUE

stock

✦ Scarecrow: Cat OT Enable

FALSE

no cat present

Δ + zero residual adders

FIX

phantom-hw cleanup

✦ SCARECROW REASONING CONFIDENCE: HIGH

The Cat OT model uses a thermal estimate based on AFR history × airmass × time and starts adding enrichment when it predicts catalyst temp > 1500°F. You don't have a catalyst, so:

Disabling the enable flag stops the model from running (saves CPU cycles, removes residual fueling decisions)
Important: the model's adder tables ALSO need to be zeroed out. Just flipping the enable flag leaves residual enrichment in some operating conditions — documented quirk in the LS1 0411 OS.

This is a legitimate tuning fix for hardware that doesn't exist on the car. It's not the same as disabling the P0420/P0430 catalyst monitors (which I won't help with) — that's a separate diagnostic suppression that you'd handle in the Diagnostics section.

The PCM tracks an estimated cat temperature. When it thinks the cat is overheating, it dumps extra fuel. On your catless build there's no cat to overheat, so this is just adding fueling decisions you never asked for.

Two-step fix:

Turn off the enable flag — stops the model from running
Zero the adder tables too — just flipping the flag leaves residual fueling in some operating conditions (documented quirk; the flag alone isn't enough)

⚖ Scarecrow Scope — Cat OT model vs. monitor disables

✓ HERE

Cat OT enrichment model on a catless car. Phantom-hardware tuning fix — the model is making fueling decisions based on a catalyst that doesn't exist. Scarecrow writes the cal change (disable enable + zero residual adders). Performance and integrity win, no monitor implications.

→ DIAGNOSTICS

P0420 / P0430 catalyst monitors, P0440-series EVAP, O2 heater monitors, readiness flags, AIR pump deletes. Scarecrow shows you what each does and where they live in HPT/EFILive — but doesn't write the disables. Lives in the Diagnostics section's monitor-posture explainer (built when we get there). Community guides on LS1Tech cover the cal changes themselves.

Why this line exists: Scarecrow v1.1 has to be distributable. SEMA's aftermarket cover assumes tools don't act as defeat-device generators — EPA enforcement has hit Punch It, Diesel Brothers, Gear Box Z over emissions deletes. The line keeps you shipping. The Diagnostics-side explainer makes the posture a credibility feature, not a hole.

1 boolean + 8 zeroed adders

1.7 Verification Loop — Don't Trust These Numbers Until You Log Them 📋 Workflow

Every PE suggestion above is a starting point, not a final answer. The only way to know your PE is right is the verification loop: command vs measured, on YOUR car.

Step 1

Verify wideband

AEM X-Series free-air calibration before pulls. Check ground at exhaust bung.

Step 2

Pull in 4th gear

4th = most heat soak. 2000→6500 RPM under load. Run 3 pulls back-to-back.

Step 3

Compare in Scarecrow

Drag log file in. Cmd vs measured AFR overlay, per-cell delta histogram.

Step 4

Iterate

Scarecrow auto-suggests next round of corrections from delta. Repeat until ±0.2 AFR.

📊

Drop a wideband datalog here (.hpl or .csv)

Or click to load a sample log — Scarecrow will compare commanded vs measured AFR per cell and split corrections honestly:
fueling-math fixes Scarecrow can apply, vs. fuel-system limits the user has to investigate.

✦ SCARECROW REASONING CONFIDENCE: HIGH

What the data tells you:

Measured richer than commanded across the board: over-fueling somewhere upstream — LTFT carryover from closed loop, injector flow data wrong, MAF over-reporting under load. Don't chase this with PE; fix VE/MAF/injectors first.
Measured leaner than commanded under high RPM/load: fuel system is the bottleneck — pressure dropping, injectors at duty cycle limit (IDC > 85%), or pump can't keep up. Don't chase with PE; you have a hardware ceiling.
Measured matches commanded: trust the numbers. Now you can shape the curve to chase peak power. Most LS1/LS2 builds find peak at 12.6–12.8. Aggressive heads/cam can run 13.0–13.1.

Power Enrichment

Scarecrow Briefing — Power Enrichment for your build