What does "Stock injector size" do?

[wagon-r]

The S300 User Manual does not discuss the purpose of the "Stock injector size" under "Fuel Trim Parameters".

The basemap I got from my tuner (Pure Tuning in Toledo) was running lean everywhere except during closed loop. He set the "Current injector size" correctly, to match the 345 cc H22 injectors I am using, and he set "Stock injector size" to 240, which correctly matches the original injectors on my F22A engine.

I changed the Stock injector size from 240 to 345 in my S300, to match the Current injector size, and now the engine is running rich except during closed loop. So, clearly the Stock injector size has an impact on the amount of fuel injected. I would just like to understand why this is occurring.

[Spunkster]

It changes the amount of fuel added. If a stock injector was used, then 650 cc injectors are put in you will get way too much fuel, so you then tell the software you have larger injectors and it will cut back on the duty cycle to compensate for the higher flow rating.

If it was tuned with improper settings but runs right, then you should leave those settings alone or you will have to retune on the dyno again.

[wagon-r]

I think what you are saying is that if the vehicle was tuned with one set of injectors and, after the tune, the injectors were changed, then you put the original injectors used for the tune under "stock" injectors and the new set of injectors under "Current", so that the amount of fuel delivered is unchanged from the tune.

In my case, I haven't been able to eliminate a Code 9 and my tuner (rightly so) won't tune until I eliminate all codes. So, I'm trying to get the base map to work properly. For the base map, I think the "Stock" injector size should be set to match the "Current" injector size.

Please let me know if my understanding is not correct.

[Spunkster]

If you have a code 9 then it is either the ECU itself, or the distributor and should have nothing to do with the injectors.