Figure 1: The beast at peace.
PORTING THE ZETEC THROTTLE BODY
Before you start, you'll need
-a Dremel electric grinder (or equivalent), or some files (takes longer), or I've even heard that you can use a holesaw.
-high-temp epoxy. Usually can be found at auto parts stores, etc, for around $3-5. Get the kind that mixes from two parts. Choose color to suit.
-safety goggles/glasses. Not even kidding. I had to take a break halfway through because a chunk of hot plastic landed in my eye.
-a straight blade and a Philips head screwdriver.
-a good nutdriver with a straight blade bit, a Philips head bit, and a T-30 bit. *DO NOT* use a socket wrench, or you maximize your chances of messing up your intake manifold.
-a rag, an old t-shirt, something like that.
-some patience. This goes along with the above mention of messing up the intake manifold. TAKE YOUR TIME, or this simple $5 operation will become much more expen$ive.
Be careful during all steps to NOT dislodge any vacuum lines attached to the intake manifold. Also, wait until your car cools down, so you don't inadvertently burn yourself. Ok, open the hood. Unhook the negative battery cable.
Figure 1: The beast at peace.
Locate the throttle body, and remove intake piping. Use the T-30 bit to remove the four screws that secure the throttle body to the intake manifold. Once you have them out, remove the throttle body from the intake manifold, and stuff the rag/shirt into the manifold. We don't want any foreign bodies falling in there while we have the throttle body off.
Figure 2:What the throttle body will look like when you're done.
Now you'll need to remove the TPS sensor from the driver's side of the throttle body. This sensor is very sensitive, very prone to breaking, and rather important to the healthy operation of your engine. *DO NOT* use excessive force when removing or reinstalling the TPS sensor. Unplug TPS sensor and remove the two screws securing it to the throttle body. Remove the throttle cable and cruise control (if applicable) cable bracket from the front of the throttle body.
With the throttle body in hand, look at the backside of the throttle body, the side that faces the firewall. Notice that lip on the inside and the crease on the outside? That's what we're eliminating today. Make your way to wherever you have your epoxy and Dremel. Familiarize yourself with the epoxy's directions, and prepare the mixture to be applied in the following manner. You'll want to fill in all of that crease you see on the outside back of the throttle body. Fill it in well; don't be afraid to put that epoxy on there. Follow the epoxy's directions for curing, and let the throttle body sit for that length of time. Go read a magazine, or browse Focaljet.
Once the alotted period of time has elapsed, grab your Dremel, don your safety glasses, and get ready for the fun part. I used one hand to force open the throttle plate, and one hand to bore out the inside of the body. The goal is to get the inside to be as much of a circle as possible, without punching a hole through the plastic or the epoxy. If you'd like you may also grind off those little ribs, but don't take a lot of plastic off of the idle air bypass hole, and definitely don't epoxy it shut, or your car will not run right. At this point you should have a ported throttle body in your hand, ready to go back on the car. Go ahead and wipe any excess dust off the inside of the reworked piece and make you way back to the car. Remember to remove the rag from the intake manifold before reinstalling the throttle body.
*IMPORTANT* - your intake manifold is PLASTIC, those screws that secure the throttle body to it are METAL...if you cross-thread those screws back into the manifold, you *WILL* damage it beyond repair, causing you undue stress, aggravation, and cost. Take your time when reinstalling those four screws, and you won't damage anything.
Here's how I did it: I put the screw into the hole, and turned it to the left until I felt a small "click". That's when I knew that the screw was in its thread, and I started turning it slowly and easily to the right. If you feel ANY resistance at all, you are cross-threading it - try again.
Once you have those four screws in, reattach the TPS sensor CAREFULLY, like I said it's quite sensitive so don't bash it in. Reattach the throttle and cruise control cable bracket. Reattach negative battery cable, close hood, and take the car for a test drive. Notice anything different?