Idle Air Control Valve - Stalling/Poor Idle/Surging

22/03/96

19/03/96/US

SUBJECT:
Stalling/Poor Idle/Surging

MODEL:
Range Rover Classic
Discovery
Discovery
Defender 90

AFFECTED VEHICLES:
LP 661835 to 663534
LJ 152765 to 164227
LJ 500000 to 515006
LD 965085 to 980154

DETAIL

During mid to late 1995 a number of faulty stepper motor (Idle Air Control Valve) castings found their way into production of 14CUX vehicles and the parts supply. This bulletin will help identify the faulty castings and also identify the problems they cause. Problems encountered are as follows:

The restriction caused by the faulty casting affects the idle speed control, especially on cold start.

1. When the vehicle is started, especially when cold, there is no increase (1200-1500 rpm) in the engine speed with a slow tail off.

2. When the vehicle has been started and the idle speed is low, it may stall when loaded (i.e. with PAS or when Drive is selected).

3. When the engine is warm a fault may not be noticed.

4. Under cold weather conditions the engine may not start "foot off" throttle.

ACTION REQUIRED

Upon customer complaint of stalling/poor idle and surging the air by-pass stepper housing should be removed and checked for the condition stated above, if, a faulty motor stepper housing is found follow the below procedure.

PARTS INFORMATION

Loctite 242 - Source Locally

PROCEDURE

Refer to the Workshop Manual section 19 "Idle Air Control Valve."

Description





1. The aperture on faulty castings is approximately 0.315 x 0.118 in (8x3 mm) (on normal castings the aperture should be 0.433 x 0.433 in (11x11 mm)).





2. Corners marked in illustration are square on faulty castings (normally they should be rounded).

3. On good castings, IACV spring is clearly visible, but more difficult to see on faulty castings.

What to Do

If above symptoms are present and a IACV housing is fitted to vehicle, remove housing, remove stepper motor from housing and file down housing aperture to meet specifications as outlined above. when the IACV is refitted use Loctite 242 on the threads before installing. Remember to RESET IDLE on a fully warm engine and transmission.

WARRANTY
Normal warranty policy and procedures apply

COMP.CODE
7W1C

SR0

19.22.54/01 - Modify Idle control housing 0.25 hr.