Throttle Body Bypass
|Tools & parts you will need:
|BMR Throttle Body Bypass Kit*
* We found that it is easier to order the parts for the small price rather than run around town all day hunting down the parts.
Car: 1999 Z28 Camaro, 13,850 miles
Installers: Eric and Kelly Barger
People who helped us from major tech talk to general advice:
Elmer Boggs (eboggs_jkvl)
Perform all these installs at your own risk. Know how to use all of your shop equipment and take necessary safety precautions when performing ANY modifications and or maintenance items to your vehicle. Seek the advice of a paid professional and do not substitute this publication for the advice of a paid professional. This product is how we accomplished our installs and is not meant to be carved in stone. We are not responsible for a mistake, misprint, or any other error found in this guide. This guide is intended as a supplement and not to be your only source of information.
Purpose: This modification will eliminate the heated coolant flow through your throttle body. This will cool down your throttle body, which in turn decreases the temperature of the incoming air. This will hurt cars in cold climates or during the winter months. However, most southern states will not have a problem with this mod during the winter.
Preface: Before you start into this install be sure you know how to use all of your shop equipment. Take your time and be careful.
Reminder: Make sure you have the keys out of the ignition. Why? When you remove the sensors from the air box lid assembly you do not want to start the car. You will set the Service Engine Soon (SES) light. If you do start the car without placing the sensors back in, you can easily reset the SES light by following these steps:
1. Turn key to the "on" position but don't start car 2. Pull the PCM BAT and PCM IGN fuses in engine compartment 3. Wait approximately 5 minutes 4. Turn ignition off 5. Replace fuses 6. Start the car and then make sure the light has gone off
1. Open the hood of your car and look in the front and center of the engine compartment. Locate the air box lid metal clamps (see blue arrows in Figure 1).
2. Go ahead and undo the air box metal clamps (see blue arrows in Figure 2).
3. Now you will have to remove the two plastic clips that hold down the air silencers (see blue arrows in Figure 3). Refer to Figure 4 for the three-step process to remove a pushpin.
A. Locate the pushpin on the driver's side of the air box assembly. B. Place a flat-head screwdriver underneath the head of the pin while holding down the "collar" portion with your thumb. C. Pull pin up and remove.
Make sure to keep the clips just in case you need to replace your factory air box lid for a trip to the dealer or other need. If you do break the clips they come in packs of ten (10) and are really cheap. The GM part number is 12551599.
4. Locate the wire harnesses from the intake air temperature sensor on the air box lid, the mass-air-flow sensor and the two throttle body sensors (see Figure 5).
5. Remove the four wire harnesses from the air box assembly that are shown in Figure 5. You can see an example showing how to remove the sensor connectors safely in Figure 6. Gently pull the tab out and lift the sensor out of the housing. Moving these wires out of the way makes it a lot easier to perform this modification.
6. Go ahead and locate the rubber flexible hose that runs from the mass-air-flow housing (MAFH) to the throttle body (TB) (see blue arrow in Figure 7). Take a flat-head screwdriver and loosen the metal clamp.
7. Grab hold of the air box, lift and pull towards you (see Figure 8).
8. Locate the driver's side of the throttle body and find the rubber hose that exits the throttle body on the driver's side. Place a small rag underneath the area where you are going to remove the rubber hose. A small amount of coolant will spill out. Squeeze the hose clamp on the rubber hose and slide it back down the hose a little ways. Remove the hose from the metal line (see Figure 9). Removing the hose can be quite difficult. We used a flat-head screwdriver and gently pried the hose back. Once the hose moved a little the hose came off with ease.
9. Place a rubber cap on the metal line exiting the throttle body (see Figure 10). You just pulled the hose off this line.
10. Locate the passenger's side of the throttle body and find the rubber hose that enters the throttle body on the passenger's side. Place a small rag underneath the area where you are going to remove the rubber hose. A small amount of coolant will spill out. Squeeze the hose clamp on the rubber hose and slide it back down the hose a little ways. Notice we did not illustrate this in Figure 11. Remove the hose from the metal line (see Figure 11). Removing the hose can be quite difficult. We used a flat-head screwdriver and gently pried the hose back. Once the hose moved a little the hose came off with ease.
11. Place a rubber cap on the metal line entering the throttle body (see Figure 12). You just pulled the hose off of this line.
12. Now you want to take the end of each line you removed and place the metal bypass adapter into each line (see Figure 13). This can be really difficult so take your time and have some patience. It took us about 5 minutes to fit the adapter into the rubber hose on the driver's side of the throttle body. When you get the hoses on the adapter, move the clamps back to the ends of the line.
Notice in Figure 13 the driver's side of the hose is not pushed all the way to the middle. You want to try to get the hose as close to the middle as possible! We test drove the car and found no leaks so we are comfortable with it in that position.
13. Grab hold of the air box lid (refer to Step 7) and push the rubber boot back on the throttle body. Make sure you get the rubber boot all the way back on the throttle body. Then tighten the metal band clamp on the rubber boot (see blue arrow in Figure 14).
14. Reconnect the wires to the IAT, MAF, and two throttle body sensors (see blue arrows in Figure 15). If you do not you will get the Service Engine Soon (SES) light on your dashboard. No big deal but it is nice to avoid the hassle if you can. If you do set the light you can reset your PCM by using the steps mentioned in the Reminder.
15. Reconnect the air box clamps and push pins. That completes this short install!
Comments: The Throttle Bypass is a good modification to perform. The only drawback MIGHT be limited to those who live or experience cold climates. During the months of cold weather it MIGHT be a good idea to place the original hoses back on. Many people have run this modification through harsh winters without experiencing ANY drawbacks. Every little bit adds up and this modification is no exception.