GTO - Service Adjustment Procedures

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Index

Curb Idle Speed adjustment
4WS/4WD Power Steering Fluid
Intake Plenum Removal (Plug replacement)
K&N Filter Installation
Electronic Controlled Suspension
4-Wheel Steering System Check
Fluid Level Warning Lights
Radio Removal and In-Dash Installation
Simple (but common) Problems
Pressure Conversion Information
Headlamp Replacement

A) Adjusting the Curb Idle Speed

The curb idle speed of your vehicle should be 700 +/- 50 rpm and can be adjusted using the SAS (Speed Adjustment Screw). This screw can be adjusted with a large philips or flathead screwdriver, and should be turned anti-clockwise to increase curb idle speed.

Section 13-32 in the service manual deals with this. (Step 6, onwards)

B) Topping up the Power Steering fluid

If you are getting the "4WS Oil" warning light displayed when turning the steering wheel hard (either at speed or idle) then there is a good chance that your Power Steering fluid is a little low. This can be topped up with MOPAR ATF PLUS (Automatic transmission fluid type 7176)/ATF DEXTRON or DEXTRON II. The location of the reservoir is shown by the arrow in the picture.

NOTE: The light can be found at position 30 on the Dashboard diagram

C) Intake Plenum Removal (Plug replacement)

This is a picture of the Intake Plenum having been removed. The removal of it is fairly easy as long as you have the diagram handy (Section 15-14 in the service manual).
One suggestion I do have is to label (with a marker/vivid) each bolt and the location on the diagram with an increasing number so that the whole process can be easily reversed when putting it back on. I was unable to get a couple of hoses removed as they were just too tight (see arrows in diagram), these however did not cause a problem as I simply flipped the plenum on it's back.
I have attached a compiled list of messages about this task. The first is the best (from Troy Buccini) which details what needs to be done. Note that where he states that "there is a pipe that flexes on the drivers side back of the intake plenum. There is a metal gasket between the pipe and the plenum. Don't drop it.", I was unable to find this pipe (mine is a '91 GTO-VR4, Japanese import). Looking at the plenum diagram I am missing all EGR components.
UPDATE: There are now some great websites detailing the "operation", here is the turbo, and non-turbo site.

D) K&N Filter Installation

Note: The K&N FIPK (Filtercharger Injection Performance Kit) is an aftermarket replacement for the restrictive stock airbox which is attached to the MAS. You will get an aluminium adaptor that bolts onto the MAS to which you attach the filter element.
Disconnect the NEGATIVE terminal from the battery (leave disconnected for 10 minutes). This is needed to reset the ECU so that it can adjust to the increased airflow.
Following the provided intructions the installation is fairly straight forward. Just make sure you have all the tools (allen keys) and be careful not to damage the honeycomb within the Mass Air Sensor box.
Here is an illustration of how the K&N connects to the Mass Air Sensor.

E) Electronic Controlled Suspension

If you are having trouble the first thing to check are the wires leading to the front shocks (these have a habit of failing).
You can check the ECS by bringing your ear near the top of the shock absorber and listening for the operating sound of the actuator whenever the control mode is changed by pressing the ECS switch.
The damping force can be checked by simply bouncing the mounting points in both modes and checking that the damping force is harder in the Sport state.
Here is a writeup of control features in Tour mode.

F) 4-Wheel Steering System Check

To check that the 4WS system is functioning correctly:

Raise the vehicle so that all four wheels may turn freely.
Start the engine, running the vehicle at an indicated speed of about 80km/h (50 mph).
Turn the steering wheel all the way to the left and right and turn it swiftly, checking to ensure that the rear wheels steer to the same directions as the front wheels.
Please note that we are only talking about a 1.5 degree shift in direction.

This information was found on page 37B-5 in the Service Manual.

G) Fluid Level Warning Lights

This diagram shows the position of the two commonly mixed up warning lights. Many people get confused with the washer fluid warning light looking very similar to an engine coolant (radiator) warning light.
In many instances it is simple a matter of topping up the washer fluid (front and rear) to get rid of the warning.

NOTE: These lights can be found at 26-29 on the Dashboard diagram

H) Radio Removal and In-Dash Installation

Note: The factory radio is a double din type radio. An installation kit is necessary for proper installation of any aftermarket radio.
Disconnect the negative battery cable.
Using a panel removal tool (or flathead screwdriver), carefully remove the radio trim bezel by prying outward (preferable from the bottom) and releasing the snap clips securing it to the dash.
Extract the (4) screws securing the radio to the dash, unplug all connectors and remove radio.
Here is a Manual entry on stereo/speaker removal

I) Simple (but common) Problems

Having trouble with your pop-up lights, or passenger side window?
It could be that you have accidently pushed one of two annoying buttons...
If your pop-up lights are unwilling to go down, then the most likely problem is that you have pressed the "please stay up" button. This is situated under the button for the fog/aux lights (as seen by the arrow in the diagram). One good use for this button is to clean the headlamps without having to turn the car on.
If you are having trouble getting the passenger side window to work, then it could just be that you have mistakenly pressed the power window lock button (WDO lock) situated on the driver side window control panel.

J) Pressure Conversion Information

Note: There are many different boost controllers and gauges out there and they all seem to measure pressure in different units (bar, psi, kPa or kg/cm²).

The way I see it a bar is equal to the following:
 1 bar = 14.504 psi = 1.0197 kg/cm²

For conversion to PSI (lb/in²) use the following:
 1 bar     = 14.504 psi
 1 atm     = 14.7 psi
 1 kg/cm²  = 14.22 psi
 1 kPa     = 0.145 psi
 1 N/m²    = 0.000145 psi

K) Headlamp Replacement

I replaced my headlamps with Hella Part Number 1042. These are 165mm headlamps for a four headlamp system. Do not worry that we only run a two headlamp system as they fit perfectly.
Here is a small writeup of the installation (along with a few pictures).