Project FR-S was hooked to the Dyno and Shawn made a baseline pull. Our car was so lean, that he didn’t even make a full pull! The car was running leaner than 14:1 even in the fat part of the torque curve!
Shawn immediately added fuel so that the car could safely do a full pull on the dyno.
Shawn added fuel across multiple maps. Like all late-model cars, the FR-S has many maps for fuel and timing, and simply tuning one of them will not give consistent operation in the tuned mode. This is what was going on with our car previously and since the Innovate kit has been discontinued, the tune was never updated by the manufacturer. Shawn has the knowledge to change all of the necessary maps to get the car to run correctly all the time.
Shawn added a ton of fuel to bring the AFR from a shocking leaner than 14:1 to a more manageable 11.8 or so. This is a testament to how forgiving direct injection is. Direct injection cools the cylinder reducing the chances of detonation and it was working well enough to run for years on the street and several track days with no problem. If this AFR was being run with port injection the car would have detonated itself to death immediately. This change in AFR is a huge difference that will give our motor a much bigger margin of safety. Shawn also got rid of the feature that greatly advanced the timing when the throttle was lifted. Now we would not have to worry about hurting the engine under deceleration. A side effect we noticed is now the car sort of sounds like it has a crackle tune. We think the ECU retards the exhaust cam closing under lift throttle for emissions and the advance was to reduce the crackle. We will take crackle to be easier on the engine!
Here is how the car’s AFR was before and after tuning and after the car was run at WOT for a while to trigger the lean shift from the ECU. The pink line was the leanness after Shawn added enough fuel to do a complete dyno pull. As you can see the AFR is around 13.5:1, way too lean! After tuning, the green line was where the car ended up, at about 11.7-11.8:1.
5 comments
Wow. I had no idea DI made such a difference in detonation resistance; those AFRs were crazy lean!
Does this mean that OEM direct injected calibrations for turbo motors are probably just running in the 13s and 14s all the time (including WOT) in the pursuit of fuel efficiency and emissions and pulling timing as needed when any knock is detected?
Modern cars run pretty lean. Especially DI ones.
I hate to nitpick (or do I?) but you should really be running Iridium plugs!
Those are the OEM plugs and also the best for racing in a different heat range. They resist erosion the best.
Shawn is a great tuner and nice guy. He has been our goto for years. He knows his way around most all ECUs.