Tuning is systems engineering, not sliders.
This pillar explains modern ECU/TCU tuning using relationships, diagnostics, and decision logic—without proprietary tables or map “leaks.” The goal is repeatable performance and safety margin you can understand.
Beginner → Intermediate → Advanced path
Use this path to keep your learning (and your build decisions) in order. If you’re unsure where to start, filter to Beginner and work forward.
Beginner
Mental models and safe fundamentals.
5 page(s)
Intermediate
Fueling, limiters, and practical troubleshooting.
13 page(s)
Advanced
Logging, validation, and decision logic.
7 page(s)
Browse
Browse by topic area. Each page links mostly within the Tuning pillar, plus the relevant mods page that supports the concept.
Filter by level
What tuning is NOT
- Not “peak dyno numbers at any cost.”
- Not copying someone else’s file without understanding your conditions.
- Not disabling safety systems to hide interventions.
- Not a replacement for tires, brakes, cooling, and maintenance.
Fundamentals
How ECUs think, torque control, and boost basics.
Boost control basics: wastegates, targets, and why boost ≠ power
A practical boost control explainer: wastegates, boost targets vs actual, and how torque-based ECUs manage airflow.
ECU vs TCU tuning: what each one controls (and why it matters)
ECU vs TCU responsibilities, torque arbitration, and why transmission limits can feel like “no boost.”
How does ECU tuning work? (A systems explanation)
An ECU tuning primer: what the ECU controls, how sensors close the loop, and why modern cars are torque-based.
What is a safe tune? (Street vs track vs climate)
Define “safe” tuning using margins, conditions, and diagnostics—without proprietary map talk.
Why more power isn’t always faster (traction, heat, and torque control)
More peak power can be slower when traction, heat soak, and torque intervention dominate the result.
Fueling & Combustion
Lambda, octane, DI/PI, and fuel system limits.
AFR vs lambda explained (and why lambda is universal)
AFR vs lambda, fuel-type differences, and the air mass ↔ fuel mass relationship.
Direct injection vs port injection: limits, benefits, and tuning implications
DI vs PI tradeoffs, fueling headroom, and what “fueling limit” looks like in real behavior.
Ethanol tuning: benefits, tradeoffs, and when it doesn’t help
Ethanol’s knock margin and cooling benefits vs cold start, consumption, and consistency tradeoffs.
Fueling limits: HPFP vs LPFP vs injectors (and what it looks like)
HPFP/LPFP roles, injector duty concepts, and why fuel limits can masquerade as timing/knock problems.
Octane, E10, E30, E50: what changes (knock margin vs energy density)
What octane really affects, why ethanol can add knock margin, and where tradeoffs show up.
Power Control & Limiters
Torque limits, throttle closure, and gear-based behavior.
Boost vs timing: how tuners balance airflow and combustion
Why timing can matter more than boost on knock-limited setups, and how balance changes by goal.
Gear-based tuning: why different gears behave differently
Why gears change load, traction, and protection behavior—and how to think about street vs track tuning.
Throttle closure explained: safety, airflow control, and what it feels like
Why the ECU closes throttle under boost, what causes it, and how to interpret it without hype.
Torque limits (ECU/TCU): why your car “won’t hold boost”
Torque modeling, driver request vs allowed torque, and how limits show up as boost drop or throttle closure.
Why boost drops under load (limits, heat, and knock response)
A decision-tree guide for boost drop: torque limits, thermal protection, knock response, and mechanical basics.
Safety & Reliability
Knock, heat soak, plugs, and failure modes.
False knock vs real knock: how to tell the difference in logs
Mechanical noise sources, how false knock appears, and what you can safely change before chasing timing.
Heat soak and IAT management: why the first pull lies
IAT vs coolant vs oil temp, heat soak behavior, and how to build repeatable comparisons.
How tunes damage engines (detonation, pre-ignition, and over-torque)
The main failure modes from bad calibration decisions—explained without map details.
Knock correction explained: what it means (and when to stop)
What knock sensors detect, why timing is corrected, and how to judge normal vs dangerous behavior.
Spark plugs: gap and heat range (and why it matters on boost)
Gap vs boost, heat range vs detonation risk, and how misfire can be confused with knock.
Data, Logging & Validation
What to log, how to read logs, and repeatability.
Clean pull vs dirty pull: why comparisons fail
Heat, slope, traction, and driver inputs—how to keep pulls comparable and avoid false conclusions.
How to read a datalog: a cause → effect table
A field-by-field interpretation approach: what changes first, what it causes, and what to fix.
Repeatability and consistency: the only way to trust gains
Why consistency > peak numbers, and what to control when validating changes.
Street vs track vs dyno tunes: what each is good at (and why they differ)
Different constraints, risks, and data quality across street, track, and dyno environments.
What to log on a tuned car (minimum fields that matter)
Required vs optional fields, what each indicates, and how to keep logs comparable.