Tools needed:

• Throttle body

• Flat blade screwdriver

• 3/8" drive ratchet

• 3" 3/8" drive extension

• 10mm 3/8" drive socket

• Needle nose pliers

• Torque wrench capable of 9ft. lbs.

Tools recommended:

• Throttle body gasket

• 1/4" rubber cap (or rubber nipple if supplied on the new throttle body)

• A few shop rags or paper towels

IMPORTANT:

All information provided here is done so as an educational resource only.  Jim Pappenfus and Z06Vette.com is not responsible for anything that happens to your car as a result of information provided here.  Be safe and use your head when working on your car.

Purpose:

Replacement of the stock throttle body with a ported and/or polished unit will increase airflow into the engine, as well as improve air velocity and pattern into the engine.  The mechanical swap of throttle body's is relatively painless and easy to perform.  Expect install time to be 30 minutes to an hour, depending on your proficiency and experience.

Abstract:

This procedure will comprise of removing the stock throttle body from the vehicle, and replacing it with a new throttle body.  In its unmodified form, engine coolant is passed through the throttle body on it's path back to the radiator.  This system is pressurized, and the coolant itself is generally in the 200 degree range.  200 degree coolant is not the most comfortable thing to splash onto your hands, it is recommended that you let the car sit overnight before performing this procedure.  The reasoning behind this is two fold.  The temperature of the coolant will have returned to ambient temperature, as well as relieved some of the pressure in the system as it drains back towards the overflow tank and radiator, out of the block and heads.  You definitely can do the procedure on a hot motor, it simply isn't as comfortable to do so, and you may lose more coolant in doing so.  Note that if you perform this procedure on a cool motor you may not need the 1/4" rubber cap mentioned in the tools section.

Procedure:

• Ensure that the car is off and the key is out of the ignition. Open the hood and locate the battery.  Disconnect the red positive terminal before proceeding.  What you see before you should look similar to Figure 1.

• Using the flat blade screwdriver, loosen the screw clamp holding the air bridge to the throttle body.  Slip the end of the air bridge off of the throttle body and rotate it to the side.  *Note* Those of you with stock air bridges may need to remove the air bridge from the MAF end as well, and completely remove the air bridge from the car. See Figure 2.

• Unplug the wiring connector to the Throttle Position Sensor (TPS), this is located on the passenger side of the throttle body.  Use special care when handling all electrical connectors.  Do not expose them to water or coolant, and do not carelessly set them aside.  Be GENTLE!  See Figure 3.

• Unplug the throttle wiring connector to the electric motor on the drivers side of the throttle body.  Use the flat blade screwdriver to depress the connector tab and gently wiggle the connector loose.  See Figure 4.

• Using the needle nose pliers, compress the GRAY spring clamp holding the coolant return line from the throttle body to the radiator.  Gently wiggle the clamp approximately 2" down the line, or until it no longer is grasping the hard line inside the hose.  DO NOT remove the hose yet!  See Figure 5.

• Remove the coolant overflow tank cap.  This is located on the passenger side fender well and has a yellow sticker on the cap.  Do so VERY SLOWLY.  Allow any pressure to escape the tank.  Leave cap off for now.

If you are performing the procedure with the car hot, proceed with caution at this point!

• Keep the 1/4" rubber cap or nipple close by, and gently work the rubber hose off the end of the hard line.  If the car is hot then very hot coolant will begin shooting/spilling out of this line.  Place the rubber cap or nipple over the end of the line as quickly as possible to prevent spillage.  Keep the rubber hose in the upright position!  Gently place the hose against the AC lines on the passenger side fender well, still pointed up to prevent spillage.  See Figure 6.

• Gently remove the PCV return line from the throttle body.  Lay it aside and out of the way.  See Figure 7.

• Using the 10mm socket/extension/ratchet setup, remove the three 10mm bolts holding the throttle body to the intake manifold.  Figure 8 shows the GM technical drawing with the bolt locations.  Gently lay the throttle body forward and let it rest.  Place the bolts on the windshield tray so you don't lose them.

• This is possibly the trickiest part of the operation.  Use the needle nose pliers to compress the GRAY spring clamp holding the short rubber hose from the coolant lines at the heads to the throttle body.  See Figure 9.  Work the clamp down the rubber hose towards the throttle body.  Remove the rubber hose from the hard line at the heads.  The pressure should be relieved from the system now, and very little, if any, coolant leakage should occur.  Remove the throttle body with the attached rubber hose from the car and take it to the bench.

• The service manual calls for removal and replacement of the throttle body gasket attached to the intake manifold at this point.  I did not replace the gasket but you should make your own assessment of the situation and make your own decision as to whether or not you replace the gasket.

• Using the pliers, compress the spring clamp holding the rubber hose to the throttle body's hard line.  Remove the rubber hose from the throttle body and place it on the new throttle body in the same location, on the same hard line.  See Figure 10.

• Inspect the new throttle body, ensure there is nothing obstructing the throttle blade, and that you have removed all items that it may have been shipped with (tags, rubber nipples on the lines, etc...).  If the throttle body is dirty or has grease/grime inside it, use some throttle body cleaner to wipe it out and clean it.

• Place throttle body in resting position in engine bay and slide rubber hose back onto the hard line from the heads.  This is tricky, and may get frustrating.  Remember to be GENTLE, more progress is made here with a cool head and gentle prodding of the hose.  Make CERTAIN to seat the hose all the way up the hard line.  Use the pliers to compress the spring clamp and slide it back up the hose to firmly hold it to the hard line.

• Replace the 3 bolts that hold the throttle body to the intake manifold.  Get each bolt started before torqueing them down.  *Note* Service manual calls for 106 in. lbs. (~9 ft. lbs.) of torque to these bolts.  Remember, the throttle body is aluminum, but the intake manifold that you are bolting it to is composite plastic.  You muscle heads can crack the intake if you try to over tighten the bolts.  9 ft. lbs. is perfect, use your torque wrench properly set to 9 ft. lbs. and double check each bolt once complete.

• Reconnect the PCV line to its fitting on the throttle body.

• Carefully, so as to avoid spillage, slip the rubber return hose to the radiator back onto it's appropriate fitting.  Be certain that it is seated all the way up the hard line, and use the pliers to reseat the spring clamp to ensure the hose remains on the hard line.

• Reconnect the TPS sensor connector on the passenger side, ensure that the clip "snaps" into place properly.

• Reconnect the throttle wire connector to the electric motor on the drivers side.  Ensure that the clip "snaps" into place properly.

• Replace the coolant overflow tank cap, be sure it is firmly screwed into place.

• Replace the induction air bridge and fit it properly over the end of the throttle body.  Ensure that there are NO leaks and that it is seated firmly against the throttle body.  Use the screw driver to tighten the screw clamp around the coupler/throttle body.  This job isn't as easy as it looks, it may be beneficial to use two people here.  One person to hold the air bridge against the throttle body and the other to tighten the screw clamp may work best.

• Reconnect the red positive battery terminal.

• Make a visual inspection of all coolant lines, electrical connectors, rubber hoses, and bolts.  Ensure that all is in order and firmly fastened together. 

• Start the car with the parking brake on, and in neutral.  Immediately get out of the car and inspect the coolant lines for any leaks.  If there is leaking, immediately shut the car down and correct the problem.

• Check the coolant level and add coolant/water as necessary.  Only use approved coolant as specified in your owners manual.

• Drive the car around the block, or up and down the street a few times, make sure no codes are thrown with the addition of the new throttle body.  If all is well and several power cycles have proven uneventful, go enjoy your new product!

Updated:  08.27.02