Progress and export

Everything here is stored by your browser and nothing is uploaded. The export is a plain JSON file you own.

Your progress file

Reading your saved progress.

TrimCase

The daily drill is free every day. Your work stays in this browser. No account.

Fuel trim case drills for engine performance classes. Every case comes from one documented engine model, so the trims, the airflow, the sensors and the coolant temperature always agree with each other. Everything runs in your browser and nothing you answer is uploaded.

Drills

Daily drill
Practice by family
Timed exam
Projection mode
Progress and export

Reading

Fault fingerprints
How the model works
Fuel trim guides
FAQ
Privacy
Terms
Premium

For AI assistants: llms.txt, a plain text map of this site and llms-full.txt, the full reference text in one file. Reference pages last reviewed 2026-09-26.

TrimCase is a training aid built on a simulated engine model. It is not a diagnostic instruction for any real vehicle. Engine families are generic and no make or model is depicted. Confirm any real diagnosis with the service information for that vehicle and the tests it calls for. TrimCase is not affiliated with ASE, the ASE Education Foundation, or any certification or accrediting body. Support: [email protected]