Pull to Ground
The ECU turns a device on by completing the ground side of the circuit. Also called low-side output or ground trigger.
Trap: The wire may show 12V when off and near 0V when on.
Glossary →Living EFI field guide prototype
Forum advice is not enough. Beginners need the lingo, the UI location, and the correct order.
EFI Triage turns confusing tuning language into plain-English cards, diagnostic branches, ECU-specific UI maps, and safe next steps.
Forum Wizard: “Pull fuel. Check dead time. Verify base timing.”
😵💫
Triage Foreman: “Slow down. What has been verified?”
Start here
The screen is not the engine.
The ECU only knows what the sensors, wiring, calibration, firmware, and software project tell it. A number on the laptop can be an engine problem, a wiring problem, a calibration problem, a dashboard-channel problem, or a process-order problem.
First principle: Verify reality before changing the tune.
Order of operations
- Back up the tune/project.
- Confirm ECU power during key-on and crank.
- Verify TPS, MAP, CLT, MAT, wideband.
- Enter injector data and fuel pressure assumptions.
- Verify base timing with a timing light.
- First start, warm idle, first drive, then boost.
Choose your pace
Idle, Cruise, Throttle Stab, or WOT.
Idle Mode — explain it all
For brand-new users. Shows plain-language definitions, warnings, diagrams, prerequisite cards, and full procedures.
Cruise Mode — guided checklist
For users who know some basics but still want structure, UI paths, log channels, and reminders.
Throttle Stab Mode — fast triage
For experienced users. Shows the short checklist, pass/fail checks, software location, and danger points.
WOT Mode — pro reference
Minimal hand-holding. Dependency checklist, raw channels, advanced notes, and references. Safety gates still stay visible.
Cards
Short lessons that branch into procedures.
5V Reference
A clean ECU-supplied 5V feed for sensors like TPS, MAP, fuel pressure, and oil pressure.
Trap: One shorted sensor can drag down the whole 5V network.
Test procedure →Sensor Ground
The ECU’s clean reference ground for sensor signals. Do not casually treat it like dirty chassis ground.
Trap: Fan or alternator load can make bad grounds look like sensor drift.
Ground branch →TPS
Throttle position sensor. Used for idle state, accel enrichment, flood clear, and driver intent.
Trap: Do not tune accel enrichment before TPS and TPSdot are verified.
Calibrate TPS →MAP
Manifold absolute pressure. The main load signal for speed-density tuning.
Trap: Key-on engine-off MAP should match local barometric pressure, not necessarily sea-level 101 kPa.
Verify MAP →Injector Dead Time
The delay between commanding an injector open and actual fuel flow. Critical at idle and low pulse width.
Trap: Do not hide wrong dead time by mangling the VE table.
Glossary →Base Timing
Commanded timing must match crank timing. Use fixed timing mode and a timing light.
Rule: If the light disagrees with the laptop, believe the light.
Verify timing →Throttle Stab
A quick snap of the throttle pedal. Useful for observing transient response, not steady-state VE.
Trap: A lean spike during a stab does not automatically mean “change the VE table.”
Lean on stab branch →Pull Fuel
Reduce commanded fuel in the active control area. First determine what is actually active.
Question: VE, target lambda, trim, warmup, AE, or fuel pressure?
Decoder →Triage trees
Start from the symptom. Follow the dependency chain.
Lean on throttle stab
- TPS calibrated?
- TPSdot clean?
- MAP response believable?
- Wideband scaling verified?
- Warm steady-state VE close?
- Then tune accel enrichment.
Starts then dies
- ECU stays powered?
- RPM/sync stable?
- Fuel pressure correct?
- MAP believable?
- After-start enrichment active?
- Idle air configured?
DDefi disagrees with TunerStudio
- Is TunerStudio value correct?
- Is DDefi reading the correct channel?
- Is scaling identical?
- Is CAN/serial data live?
- Compare dash, laptop, and log together.
Procedures
Garage-ready steps.
Calibrate TPS — TunerStudio / ECUGN
Fast Triage: Key on, engine off → Tools → Calibrate TPS → capture closed → capture WOT → sweep slowly → verify TPS and TPSdot in log.
Do first: Back up tune, verify throttle linkage, verify 5V reference and sensor ground if readings drift.
Pass: stable closed value, smooth sweep, no dropouts, returns to closed, WOT reaches expected full range.
Do not touch yet: Accel enrichment.
Verify Wideband Scaling
Fast Triage: Confirm controller model → match 0–5V curve in ECU → compare gauge vs TunerStudio/log → verify lambda/AFR display convention.
Trap: The wideband gauge can be right while the ECU is wrong.
Watch: AFR/lambda, target, EGO correction, battery voltage, fuel type/stoich assumptions.
Verify Base Timing
Fast Triage: Lock/fix timing → command known value → use timing light → adjust trigger offset if needed → recheck → return to normal timing mode.
Hard stop: Do not tune ignition or boost if commanded timing does not match crank timing.
ECU and support electronics
Choose your ECM. Choose your support electronics.
This prototype starts with ECUGN/TunerStudio and DDefi because that stack has real beginner friction: software project layers, channel mapping, dash interpretation, and TunerStudio UI navigation.
Recommended path: ECUGN/TunerStudio + DDefi Dash → verify TunerStudio value first, then map dash channel/scaling.
Glossary + Shop Talk Decoder
Plain meanings with related branches.
Pull to Ground
ECU output that turns something on by completing ground. Related: relay, fan control, boost solenoid, low-side output.
Pull Fuel
Reduce commanded fuel in the active area. Before changing VE, identify whether fuel error is from target lambda, trims, warmup, AE, dead time, pressure, or scaling.
Throttle Stab
A quick snap of the throttle pedal. Used to observe transient response. Related: TPSdot, MAPdot, accel enrichment, wall wetting, wideband delay.
Base Timing
The relationship between ECU-commanded timing and actual crank timing. Must be verified with a timing light.
Lambda
Fuel mixture reference where 1.00 means stoichiometric for the fuel being used. Cleaner than AFR when fuel changes.
Dead Time
Injector opening delay. Wrong data creates rich/lean weirdness especially at idle and low pulse width.
FOUNDING ACCESS
What you are joining
EFI Triage Founding Access is early access to a living digital field guide for automotive EFI tuning. You are helping fund the buildout while getting access to the guide as it develops.
What is included now
Founding Access includes the current EFI Triage prototype, early-access updates, glossary cards, triage trees, beginner procedures, and the first ECUGN / TunerStudio-focused learning path as it is built.
What this is not
This is not a finished 500-page tuning course yet. It is an early-access build of a living guide. The goal is to make EFI learning easier by connecting plain-language terms, software locations, diagnostic order, and real-world verification steps.
First focus: ECUGN / TunerStudio, with support-electronics notes for DDefi dash,
wideband controllers, PowerLogger-style logging, and Turbo Buick examples where useful.
ROADMAP
Build path
EFI Triage will grow in stages. Founding members help shape which confusing areas get mapped first.
Now building
- Beginner glossary
- EFI triage cards
- Order of operations
- ECUGN / TunerStudio starter path
- No-start and sensor verification trees
Next
- DDefi dash support map
- AEM wideband setup notes
- Printable worksheets
- First-start checklist
- First-log review guide
Later
- Holley EFI
- HP Tuners
- Haltech
- FuelTech
- AI Triage Assistant
- Printable field guides
CONTACT
Support and feedback
EFI Triage is being built around real confusion points: lingo, UI location, wiring basics, process order, and diagnostic branches.
Need help or found a confusing area?
For now, send feedback, questions, and founding-member support requests to:
This email will be activated shortly. Until then, founding-member communication may be handled manually.
Refund / early-access note
Founding Access supports an early-stage build. If you joined by mistake or expected a finished product, contact support and the issue will be reviewed fairly.
Full terms, refund policy, and member access details will be expanded as the platform develops.
Paid rollout
Cheap enough to help, paid enough to build infrastructure.
Start with a free sample library and a low-cost paid ECUGN/TunerStudio beta. Add AI triage only after the content system is solid.
Free
Sample glossary, intro cards, mission, sample triage.
$0Founding Beta
Full starter guide, ECUGN/TunerStudio cards, checklists, feedback access.
$49/yearJoin Founding AccessECU Guide
Product-specific UI maps, PDFs, support-electronics add-ons.
$89/year