Editing Engine tuning (section)

{{Short description|Optimisation of engine performance}}
{{Other uses|Tuning (disambiguation)}}
{{redirect|Engine building|the gaming term|Glossary of board games#Engine-building|and|Game mechanics#Engine building}}
{{More citations needed|date=September 2007}}
[[File:sun 800 tester-001.jpg|thumb|Vintage engine testing equipment that can test [[ignition timing]], ignition dwell, [[manifold vacuum]] and exhaust emissions]]

'''Engine tuning''' is the adjustment or modification of the [[internal combustion engine]] or [[Engine control unit|Engine Control Unit]] (ECU) to yield optimal performance and increase the engine's power output, economy, or durability. These goals may be mutually exclusive; an engine may be de-tuned with respect to output power in exchange for better economy or longer engine life due to lessened stress on engine components.

Tuning can include a wide variety of adjustments and modifications, such as the routine adjustment of the [[carburetor]] and [[ignition system]] to significant engine overhauls. Performance tuning of an engine can involve revising some of the design decisions taken during the development of the engine.

Setting the idle speed, [[Air–fuel ratio|air-fuel ratio]], carburetor balance, spark plug and distributor point gaps, and ignition timing were regular maintenance tasks for older engines and are the final but essential steps in setting up a racing engine. 

On modern engines equipped with electronic ignition and fuel injection, some or all of these tasks are automated but they still require initial calibration of the controls. The [[Engine control unit|ECU]] handles these tasks, and must be calibrated properly to match the engine's hardware.<ref>{{Cite web |last=CarTechBooks |title=Engine Management: Advanced Tuning |url=https://www.cartechbooks.com/products/engine-management-advanced-tuning |access-date=2023-09-18 |website=CarTechBooks}}</ref><ref>{{Cite web |last=CarTechBooks |title=Designing and Tuning High-Performance Fuel Injection Systems |url=https://www.cartechbooks.com/products/designing-and-tuning-high-performance-fuel-injection-systems |access-date=2023-09-18 |website=CarTechBooks}}</ref>