How to Remove the Throttle Body From a 1994 Toyota Corolla

As carburetors slowly disappeared through the 1980s, as similar looking component -- the throttle body -- took their place. Despite the throttle body looking roughly similar with the carburetor, its functions could not have been more different. The carburetor directly regulated the flow of fuel to increase or decrease the engine speed, whereas the throttle body controls the airflow into the intake to regulate engine speed. This helps keep the fuel delivery better regulated, thereby increasing fuel economy. Replacing the 1994 Corollas throttle body is similar to replacing a carburetor, but there is no fuel to worry about.

Instructions

Removal

1

Raise the front of the Corolla off the ground with a floor jack and position jack stands under the vehicles subframe. Lower the Corolla onto the jack stands.

2

Unscrew the radiator cap from the radiator. Crawl under the vehicle and find the radiator petcock -- the plastic drain plug -- on the bottom of the radiator. Position a drain pan under the petcock and loosen it with your fingers until coolant starts flowing from it.

3

Tighten the petcock once the coolant has stopped flowing from it. Raise the Corolla off the jack stands with a floor jack and remove the jack stands. Lower the car to the ground.

4

Loosen the hose clamp securing the air intake hose to the throttle body with a Phillips screwdriver. Pull the air intake hose from the throttle body.

5

Pivot the throttle body linkage -- the component that the throttle cable connects to -- upward and hold it in that position to relieve tension on the throttle cable. Pull the end of the throttle upward, so that the cable lines up with the slot in the throttle linkage. Pull the throttle cable through the slot and remove the throttle cable from the linkage.

6

Trace the throttle cable toward the rear of the vehicle until you reach the bracket securing it to the throttle body. Remove the bolt securing it to the throttle body with a ratchet and socket, and pull the bracket off the throttle body.

7

Press and hold the locking button on the throttle position sensor -- the electrical component on the throttle body -- wiring harness and unplug the harness from the TPS.

8

Grab the PCV hose -- the hard rubber hose -- and pull it away from the throttle body. Label the nipple it connects to on the throttle body with masking tape and a permanent marker.

9

Label the two coolant bypass hoses connecting to the throttle body with masking tape and a permanent marker. Loosen the clamps holding them into place on the throttle body with a Phillips screwdriver. Pull one hose off the throttle body and label its connection point on the throttle body with masking tape and a permanent marker. Remove the second hose and label its connection point.

10

Label all of the vacuum lines plugging into the throttle body with masking tape and a permanent marker. Pull each vacuum hose off on-by-one, labeling each connection point on the throttle body.

11

Remove the two throttle body bolts and two throttle body nuts with a ratchet and socket. Pull the throttle body off the intake manifold. Remove the throttle body gasket and discard it.

12

Scrape the throttle body mating surface on the intake manifold with a plastic gasket scraper and wipe it off with a clean, lint-free cloth.

13

Remove the two screws securing the TPS, if you are replacing the throttle body with a new one, using a Phillips screwdriver. Pull the TPS off the old throttle body.

Installation

14

Transfer the TPS to the new throttle body, if applicable, and hand-tighten its screws. Do not tighten them fully, as you must adjust the TPS later.

15

Label the connections on the new throttle body with masking tape and a permanent marker in the same manner as the labels made on the old throttle body, if you are installing a replacement throttle body.

16

Verify that the throttle linkage rests on the throttle stopper screw, and the throttle plate is fully closed. If not, tighten or loosen the throttle screw until this condition is achieved.

17

Look at the terminals inside the TPSs receptacle, whose end is attached to the throttle body facing downward. The two pins on the far right are the IDL and E2 pins. Insert the probes of the ohmmeter into the IDL and E2 terminals.

18

Pivot the throttle linkage away from the throttle stop screw and insert a 0.028-inch feeler-gauge between the throttle linkage and the throttle stop screw. Pivot the throttle linkage back so it rests on the feeler-gauge.

19

Loosen the TPS screws with a Phillips screwdriver, if reinstalling the original throttle body. Pivot the TPS clockwise slowly until the ohmmeter goes from zero continuity to showing continuity. Tighten the TPS screws with a Phillips screwdriver, with the TPS in the position where it first shows continuity on the ohmmeter.

20

Remove the feeler-gauge from between the throttle stopper screw and the throttle linkage. Insert a 0.016-inch feeler-gauge between the throttle body linkage and throttle stopper screw, and verify that there is continuity showing on the ohmmeter. Remove the 0.016-inch feeler-gauge, insert a 0.035-inch feeler-gauge and verify there is no continuity. If either continuity test fails, loosen the TPS screws and restart from Step 5. If the TPS passed the continuity test, pull the ohmmeter probes from the terminals.

21

Set a new throttle body gasket on the intake manifold, and set the throttle body on the intake manifold. Hand-tighten the throttle body's nuts and bolts to hold the throttle body in place. Torque the throttle body bolts to 16 foot-pounds with a torque wrench and socket.

22

Plug the wiring harness into the receptacle on the TPS.

23

Connect the vacuum lines and cooling lines to the throttle body in accordance to the labels you put on the connectors. Tighten the cooling line clamps with a Phillips screwdriver. Press the PCV hose onto its nipple on the throttle body.

24

Set the throttle cable bracket on the throttle body and tighten its retaining bolt with a ratchet and socket. Pivot the throttle linkage upward and insert the metal end of the throttle cable into the hole in the linkage. Guide the throttle cable through the slot in the linkage and seat it in the groove in the linkage. Pivot the linkage back toward its stopper screw.

25

Press the air intake hose onto the throttle body inlet and tighten its hose clamp with a Phillips screwdriver.

26

Add 50-50 premixed ethylene-glycol-base (green) coolant to the radiator until the level reaches the base of the radiators filler neck. Start the engine and allow it to reach operating temperature -- roughly halfway up the temperature gauge.

27

Allow the engine to continue running and add more coolant to the radiator each time the coolant level drops -- the level dropping is the air purging out of the system. Once the coolant level remains steady, tighten the radiator cap onto the radiator and shut the engine off. The 1.6-liter engine holds a total of 1.4 gallons of coolant with a manual transmission and 1.55 gallons with an automatic transmission. The 1.8-liter engine holds 1.45 gallons of coolant with a manual and 1.65 gallons with an automatic transmission.

28

Take the old coolant to a used-automotive-fluid-recycling facility. Some auto parts stores take old coolant free of charge.