Tuning question...SAFCII

[Spoolin98]

I currently have a big16g, i plan on tuning with MAFT and SAFCII. I plan on later upgrading to a larger turbo, my question involves injectors. I know 580s are ideal for a 16g, but since i plan on going larger later i was going to get 680's. My question is, will it be harder for me to tune my car with 680's than with 580's with a SAFCII? I know its possible to tune it with 680's, i just want to know if its any harder to tune with 680s than with 580's. I did a search and couldnt find anything discussing this so if anyone has a link i would appreciate it. Thanks.

 

[Terrorize]

get the 680s, do it right the first time, 680s are only like 50.2% larger so its fine, either find search for some base maps to follow on your afc, and tune from there or, do it the ol skool r&d way and start at a safe boost level and start to tune from there, adjusting afc by little increments, and raising boost , at the same time until your egts, o2 voltage etc are all safe, so for instance if you turn up the boost add fuel, monitor egt,o2 etc,,,, you get the drift. good luck, hope you enjoy your soon to be and hopefully 11 sec car.(on slicks)

 

[1990EclipseGSX]

If you go with the 680's, you will probably want to get a Keydiver chip made up at the same time. If you get a Keydiver chip, it will help compensate for the insane timing you are going to get from running larger injectors. The reason it is "harder" to tune with larger injectors and an AFC is that timing and airflow are related to each other. As you tell your car there is less air (to compensate for the added fuel), your car bumps up the timing map. Having a chip made up to compensate for injector size/dead time will make tuning in 680's much easier. Plus, you won't have to worry about fuel cut.
Just my 2 cents on the matter though....

 

[LRS95TSI]

if u check my setup i am running almost -40 percent on my high throttle settings on my safc2 with 680's. i would atleast do this size of an injector if you plan on going bigger so it will allow u some room to play with. i think ud be fine with just the safc

 

[Spoolin98]

Can the MAFT dial in to 680s? If so, wouldnt that help compensate for the larger injectors? I want to get the larger ones for an upgrade later, but i dont want to have to get a keydiver chip or anything done to the ECU at this moment. If its possible to tune 680's with MAFT and SAFCII then thats the route im going to take. WIll it be noticibly harder to tune my car with 680's than 580's? Thanks again for everyones responses.

 

[xcelr8n]

You can set the base injector sizing with the maf-t and than fine tune with the SAFC, in theory that works, I dont have any experience doing it, I knwo someone who has, and hes had a tough time of it... but he has 720s FWIW.

 

[1990EclipseGSX]

Unfortunately, the MAFT's injector compensations are just airflow compensations, like the other dials. The difference is the Base dial, which is used for injector compensations, takes affect at every airflow level, instead of in a certain airflow range. Therefore, you still run into the same timing advance problem.
It is definitely possible to tune in 680's with nothing more than a MAFT and S-AFC, but it will be a lot easier with an E-PROM chip. The keydiver chip will make the correct compensations in the ECU for the extra fuel the injectors are flowing, so you won't need to run -40% on the AFC to get your fuel trims in order. A keydiver made tuning my 750's infinitely easier.
And yea, tuning generally becomes harder as you increase injector size on a stock ECU.

Chris

 

[Spoolin98]

Once again guys, thanks for all the input.