What this page does
The coolant temp correction scales the transient throttle Enrich Amount tables based on engine temperature. Fuel condenses on cold port walls and doesn't atomize well, so a cold engine usually needs more transient fuel than it does once it's warm. It can be mapped in up to 2D.
When you need it
Tune your transient enrichment on a fully warm engine first. Then, if you get a hesitation or lean stumble on tip-in only when the engine is cold, this correction is where you fix it, rather than fattening the warm tables.
What to check
- The coolant sensor reads correctly across its range. A Haltech 1/8 NPT coolant temp sensor with the right calibration keeps this honest.
- The correction tapers toward no change as the engine reaches operating temperature.
- Your wideband stays steady on tip-in at several temperatures during warm-up.
Need this diagram? Ask us and we'll send it over with advice for your build. See also the transient throttle overview.
