hosmer

iTrader: (1)

Ok, just until I get my ecu out to rtek can I use my safc to pull fuel in the high throttle to get rid of the awful studder?

91 tII
Oem 550 primaries with fic 880 secondaries
-car has a wideband

if I can do this, should I just pull 30ish percent across the rpm band or just from 3500 up?

Thanks

RotaryRocket88

iTrader: (7)

No Rtek is designed to be used with 880cc injectors, so you're going to have to tune things either way. 880 is 60% greater than 550, so you're dumping that much extra fuel up top. The secondaries come on at 3800 RPM & -2 inHg vacuum (from memory). If you remove 30% fuel from the entire RPM band, or anywhere under 3800 RPM, you will blow the engine. Slowly remove fuel from the high RPM range at 0 manifold pressure and into the positive pressure, and check the wideband every time. Shoot roughly for AFRs in the 11s under boost.

hosmer

iTrader: (1)

so, just to get this straight (sorry, new to rotories), the secondaries will only come on above 3800 and -2 inHg?


and at say, 2500rpm but with positive pressure they WILL NOT come online?


and finally, lets say 4000rpm (but light on the throttle) so -10 inHg...secondary injectors are off?


Basically it has to be a combo of both 3800+rpm and -2 inHg for them to fire....correct?

RotaryRocket88

iTrader: (7)

Correct. This is where the benefits of the Rtek chips come into play most. The 1.x chips move the injector staging point down to 3600 RPM on S5s, and the 2.x chips allow you to adjust it where you want. I personally stage mine as low as 3100 RPM because I've logged the 550cc primaries maxing out before the secondaries can come online. The 3500-3800 RPM range notoriously has a lean spot on modified cars running the stock ECU. This also happens to be where the stock turbo makes peak torque, which leads to many blown engines.

You should check out the Rtek and SAFC sub-sections in the Engine Management section of the forum. There's a lot of great information in there that will help you tune properly.