Basic Adjustment of Throttle Housing and Mechanism

1. BASIC ADJUSTMENT OF THROTTLE HOUSING AND MECHANISM

1.1) CHECKING NEED FOR ADJUSTMENT

Run engine up to working temperature.

Connect accurate tachometer to engine. Allow engine to idle.




Clamp idling valve (CIS) hose with pliers (arrow).

If engine stops or speed falls below 470 r/min, in, basic adjustment is acceptable.

Also check throttle switch as described (if not already carried out).

Proceed to next step.


1.2) CENTERING THROTTLE PLATE


Remove throttle switch from throttle housing.

Remove throttle housing from intake manifold.

Clean throttle housing thoroughly.

Throttle Body:

Loosen adjusting screw (arrow) so that throttle closes fully.

Throttle Plate Adjustment:

Loosen throttle plate (by loosening the two retaining screws slightly).

Note:
Check that plate is correctly installed, i.e., is facing in the right direction. Since edge of plate is thin, careful inspection is needed to see chamfered edge.


Hold throttle housing with plate horizontal.

Use lever to open and close throttle a few times until plate centers itself in throat of opening. (Open to approx. one-third on each occasion.)

Check that throttle spindle can be moved in and out with slight resistance.

Examine throttle housing against light. Opening around plate should be even and as small as possible. If opening is uneven, try moving plate slightly in either direction with fingers to obtain optimum clearance with housing wall.

Throttle Plate Adjustment:

Adjust spindle until end projects 22 +/- 0.5 mm beyond throttle housing as illustrated.

Note:
Specified maximum dimension of 22.5 mm must not be exceeded, otherwise spindle may bottom against throttle switch.

Tighten plate retaining screws (Torque: 0.6 +/- 0.1 Nm = 5 +/- 1 in.lb).




Turn adjusting screw until it is just in contact with lever. Screw in a further quarter turn.

Tighten locknut while holding adjusting screw.


1.3 ADJUSTMENT OF THROTTLE SWITCH

Install throttle switch without tightening screws.

(Two makes of throttle switch - BOSCH and VDO - are used. The manufacturer's name is shown on the rounded section of the cover. Proceed as follows depending on which make of switch is installed).

TPS Switch:

Turn switch clockwise.

BOSCH:
Turn switch counterclockwise until "click" is heard. Continue until stop is reached but no further. Since throttle must not begin to open, plate may be held closed with finger. Hold switch in this position and tighten screws (torque: 1.6 +/- 0.4 Nm = 14 +/- 4 in.lb).

VDO:
Place 0.25 mm feeler gauge between throttle lever and adjusting screw. Turn switch slowly counterclockwise until "click" is heard. Hold switch in this position and tighten mounting screws (torque: 1.6 +/- 0.4 Nm = 14 +/- 4 in.lb). Apply medium grade locking fluid to screws before tightening.

Recheck operation:

Throttle Stop Adjustment:

Open throttle slightly, insert feeler gauge between lever and adjusting screw, and check as follows:

- With 0.45 mm gauge, click should not be heard from switch when throttle is closed.
- With 0.15 mm gauge, click should be heard from switch when throttle is closed.


1.4 ADJUSTMENT OF THROTTLE MECHANISM




A) Mount throttle housing on intake manifold. Connect all hoses and connectors.

B) Install link.
C) Secure ball joints on link with "caps".







D) Place a feeler gauge of thickness ( t ) (see table) at throttle pulley stop. Thickness will vary depending on engine type.

E) Turn mid-section of link until the lever leaves adjusting screw and throttle switch clicks. Turn link in opposite direction until return click is heard from switch. Tighten link locknut in this position, first by hand and then by wrench (torque: 0.6 +/- 0.15 Nm = 5 +/- 1 in.lb). Hold link to prevent rotation while tightening nut.


F) Check lever clearance




Place feeler gauge of proper thickness (t) at throttle pulley stop.

Check:

- that 0.50 mm feeler gauge cannot be inserted between lever and adjusting screw.
- that 0.10 mm feeler gauge can be inserted between lever and adjusting screw.

If clearance is not between these limits, undo locknuts on link and repeat procedure from E on.

G) Remove feeler gauge at pulley stop when adjustment has been completed.


1.5 FINAL CHECK

Check that basic adjustment is OK by carrying out procedure 1.1.

2. CHECKING THROTTLE SWITCH




Check that lever rests (arrow) against adjusting screw. If not, loosen link at lever.

Open throttle slightly by operating lever or pulley. Insert feeler gauge between lever and adjusting screw, and check as follows:




- With 0.45 mm gauge, click should not be heard from switch when throttle is closed.
- With 0.15 mm gauge, click should be heard from switch when throttle is closed.

If return click is not within above limits, loosen switch mounting screws and adjust as per item 1.3.




Check lever clearance
See item F.

Check that throttle switch "clicks" when 0.15 mm feeler gauge is inserted between adjusting screw and lever, even when engine is idling. Use test mode 2 in diagnostic system to detect click. Acknowledgment code 3-3-2 should be displayed when throttle switch is opened and closed.




WARRANTY STATEMENT:
Adjust and clean throttle may only be submitted under the terms of the 5yr./50,000 mi. Emission Limited Warranty.