Unfortunately, the Apexi S-AFC DOES NOT WORK in a 7th gen Celica. So anyone who is reading this and has not purchased this product yet, take your money and get some thing else instead. It's too late for me, not only did I pay $300 for a S-AFC, I custom molded it into my center console! Oh well, at least it's a cool looking light show.
Many piggy back units do not work for our car. The reason is because the mass air flow and OBDII sensors BOTH send a voltage signal to the ECU. Making fuel adjustments based on readings from both, the MAF and OBDII is a new way of managing fuel enrichment.
When you try to make a fuel adjustment with a piggy back unit like the S-AFC, you are accomplishing this adjustment by sending a false voltage signal to the MAF. The MAF is supposed to read this false signal and relay it to the ECU. This would work perfectly fine with any other car, but not with the new Toyota's. This is because when the OBDII takes its reading and sends it's voltage signal to the ECU, the ECU will realize that the resulting fuel adjustment that it just supplied was not within stock parameters. When the ECU realizes this, it will over ride the S-AFC and return the fuel enrichment back to stock parameters.
Most people think that the S-AFC will still work when the car is at wide open throttle because the ECU goes into open loop circuit. Unfortunately, this is also not true.
On most car's, when the driver goes wide open throttle, the ECU makes no adjustments. Instead, the ECU defaults to a pre-set fuel map. However, because of OBDII, all new Toyota ECU's take closed loop fuel trim settings and applies them to open loop fuel maps. The ECU does this because it assumes that if it needed to lean out the fuel mixture when in closed loop, then the car must need to run more lean in open loop as well. This is actually a great design because the ECU can do a better job at correcting problems that cause bad fuel mixtures. For example, if you develop a vacuum leak the ECU is able to take the needed adjustments and apply them to wide open throttle fuel maps, which other cars are unable to do. It sure does suck for people who want to modify their engine though.
The Celica can only use a piggy back unit that will send a constant stock voltage signal to both, the MAF and OBDII. The FTC-1ESC accomplishes this and is available from http://www.splitsec.com/
. The Greddy E-Manage will also work, and is a great unit. With the Greddy E-Manage, you have the option of splicing into the fuel injector harness and adding pulsewidth to them, or even adding up to two additional injectors. http://www.greddy.com