22R-E Electronic Fuel Injection and Intake
The 22R-E engine uses Toyota multi port Electronic Fuel Injection (EFI). That is what the 'E' stands for. This is a wonderful fuel injection system and arguably much better the throttle body injection. This system is comprised of an Air Flow Meter (AFM), throttle body, Throttle Position Sensor (TPS), knock sensor (TCCS only), intake plenum/manifold, fuel injectors, fuel rail, fuel pressure regulator and a fuel pump. All of which is controlled by the Electronic Control Unit (ECU). There are two versions of this system, the analog version found in pre 1985 Celicas and the Toyota Computer Controlled System (TCCS) version found in 1985 Celicas. They both have pros and cons, suffice it to say it is easier to work with (modify) the older analog version.
The first thing to do when you want to start upgrading the intake/fuel injection system is to upgrade or replace the factory air box (housing the air filter). There are three options. You can simply replace the air filter with a much better K&N filter. You can replace the entire air box with an open element air filter set up (See: How-To: Upgrade to Open Element Air Filter). Or you can make a Cold Air Induction (CAI) setup, this uses one of the first two options but routs the air in from the outside. Any one of these would be a significant improvement. I personally am sticking with my open element set up because I drive in the rain. But the CAI setup has a lot of good points. Cold air is better in several ways, cold air is denser than hot air so you will be getting more air mass in the same space and it will keep the operating/combustion temperature down. Just don't try to drive through a puddle with a CAI intake or your engine might just take a big gulp of H2O!
The Air Flow Meter (AFM) reads the amount of air entering the engine so the ECU can figure out how much fuel to inject. It is simply a flapper door attached to a potentiometer. Unfortunately this small doorway is one of the biggest air way restrictions in the entire engine. Toyota made two sizes of AFM and unfortunately our 22RE got the smaller one. You can swap the bigger AFM from an 1982 Toyota Supra in with no modifications. But 1983-86 Supra AFMs had different electronics. It is possible to swap the Celica electronics into the Supra AFM case but it is a hassle. Despite the restriction AFM is a useful tool for tuning the fuel curve (See: How-To: Air Flow Meter 'Adjustment').
The throttle body is what controls how fast the engine revs and how much power it generates. This is the piece your gas peddle controls. The throttle body is a minor restriction compared to the AFM but it will help to get it bored out or replaced with a larger one. Boring out is simple, send it off to LC Engineering along with $300 of your hard earned money. Replacing it not for the novice. You will have to make it work with the fuel injection computer.
The intake plenum is generally well designed and free of restriction. But not totally free. There are two major issues with our intake plenums, the Exhaust Gas Recirculation (EGR) tube and the auxiliary air valve. The EGR tube emerges at the throttle body all the way from the back of the plenum. This can be cut back to the halfway point (Be aware, if you are in California this IS illegal). With the auxiliary air valve you are basically screwed. You can however replace your throttle body and intake plenum for a set out of a 1989 or later 22RE. This will solve both of the above problems if you can get past the installation issues. The Celica Throttle Position Sensor (TPS) wont fit, the throttle linkage is different, there is no port for the front valve cover breather, etc., these are just some issues. Simply put if you don't have an aftermarket programmable fuel injection system don't bother. You will have to modify the plenum in ways that will cancel out the gains.
The Electronic Control Unit (ECU) is the heart of the system. This computer reads all of the sensors, processes the information and controls the delivery of the fuel. You can get you chip reprogrammed but it really isn't worth it. But hey if you feel like spending $725 for 12hp send off your ECU to TRD and deal with no Celica for around 8 weeks. It is a far better idea to do away with the Toyota ECU system altogether and replace it with a programmable fuel injection system. There are three major systems that work great in our cars. Total Engine Control (TEC), Simple Digital Systems (SDS) and MegaSquirt. All of these have pros and cons.
There are four fuel injectors, one for each port. Hence multi-port fuel injection. You need to pick the size of your injectors depending on the actual horsepower your engine will generate. I wont go into the complex math (because I don't know it!) but for a naturally aspirated engine producing 150 crank HP you'll need 223cc/min at 43.5psi at 80% duty, for 175 crank HP you'll need 260cc/min at 43.5psi at 80% duty, for 200 crank HP you'll need 297cc/min at 43.5psi at 80% duty. For a forced induction engine your on your own, you can go from 300cc/min or 600cc/min.
Once you start making some power you should upgrade your fuel pump to a high volume fuel pump. This will keep the fuel pressure up. It is also a good idea to get an adjustable fuel pressure regulator and fuel pressure gauge. This is how you will fine tune your fuel injection.