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[VF] ELI5 - What happens with my tune?

ToeCutter21

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I'm doing a remote tune and have asked the tuner but perhaps replying by email is time consuming so I'm still wondering...

My SS Redline (6.0 litre AFM auto model) has been tuned. The difference is noticeable and nice. I've been telling my friends about the process and they ask what exactly is involved with tuning an engine. I know there's something about adjusting spark timing as well as fuel tables but beyond that I'm really not too sure.

Can someone explain what my stock engine tune would look like, what a 'tune' would change, and what individual differences you'd expect to find between identical engines in different cars.
 

07GTS

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a stock tune is a tune to suit 100,000+ engines and has to suit all and be within a operating range to suit all weather and abuse also so its very safe, a tuner can depending on how far each tuner goes and what mods are done to engine can vary alot, for instance with a decent mod tune if u need to tune IDLE there is about 40+ tables that affect that, or FUELING there is 100+ tables that effect that, so the list goes on with SPARK, AIRFLOW ect ect, and if u want to fine tune anything u pretty much can it just takes time to do it, tuning a stock engine is mainly removing the safety net a little and cleaning up the fueling which is not the best from factory and gearbox if auto maby a little on spark but its usually ok for stock
 

Smashfist

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Most basic tunes will adjust fueling and ignition timing advance (i.e. how far before the end of the compression stroke the spark is fired). Stock fueling and ignition is very conservative - it has to meet emissions (so usually they run it a little rich) and it has to be lowest common denominator for fuel supply (so the guy that fills his car with pool water mixed with some petrol he had in a can in his backyard).

Generally some more advance can be dialed in if you can guarantee a good fuel supply (higher octane fuel is more reliable to predict and will tolerate more advanced timing), and to optimise the fuel feed vs air into the engine for a better burn. This is why you tune with other mods (e.g. a more free flowing exhaust and intake will increase air supply so you tweak the fuel supply to go with it).

Basically the two main things you can tune are fuel/air ratio and spark/ignition advance. It's a little more complex than that as there's different places to adjust (i.e. cold start fuel tables, idle tables, loaded, lean cruise etc) but it's all the same concept applied to different operating conditions.
 
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