Coolant Temp (CLT / ECT)¶
Engine coolant temperature — the master signal for everything that depends on how warm the engine is.
What it is¶
The coolant temperature sensor (CLT, also ECT — engine coolant temperature) reports how warm the engine is. It's the single most influential temperature signal in the ECU, because so much of cold- versus-warm behavior keys off it.
The key temperatures in Engone:
| Temperature | What happens |
|---|---|
| 20 °C | The engine starts at ambient |
| 55 °C | DFCO is inhibited below this |
| 60 °C | Closed loop can run above this; warmup enrichment reaches 1.0× |
| 82 °C | The thermostat opens |
| 90 °C | Operating temperature; the knock limit loses 0.15° per °C above this |
| 95 °C / 88 °C | The fan switches on / off (adjustable) |
Why it matters¶
Coolant temperature drives a long list of corrections:
- Enrichment — cranking, after-start, and warmup enrichment all scale with it. Cold = richer.
- Cold idle — the fast-idle offset is a function of coolant temperature. Cold = higher idle.
- Knock limit and timing — temperature shifts the knock threshold and the derived timing.
How to tune it¶
CLT is an input. What you tune are the curves that read it — the enrichment and cold-idle curves that must all reach neutral at operating temperature (warmup at 60 °C, after-start and cold idle by 80 °C).
Watch out
A warm engine that idles high and rich often traces back to enrichment/idle curves that don't fully taper out at operating temperature — check them against the coolant reading. For example, check that the warmup curve reaches 1.0×.
In the game¶
The COOLANT bar in the footer TEMP box climbs from ambient at startup to operating temperature.
Use it to know which part of every temperature-based curve is active. See
Temperatures & Cooling.