Adjusting Idle Speed And Co

Note: Requirement:

Engine in perfect mechanical condition.

Make adjustments as quickly as possible to avoid excessive heat in intake ports and consequently wrong CO values.

1. Take off right air intake hose.

2. Disconnect auxiliary air pump hose on air pipe and insert a suitable plug in open air pipe (e. g. rubber grommet for doors, Part No. 999.703.163.40).

3. Install air intake hose.

4. Run engine to operating temperature (oil temperature approx. 80 to 90 °C/ 176 to 194 °F).

Use Special Tool 9122 to measure oil temperature.

5. Connect CO tester and separate tachometer to supplier's instructions.

6. Turn control screw or bypass screw on throttle housing, until speed of

700 + 50 rpm is reached.

Djet Aux Air Valve Rebuild


Use separate tachometer from tester or similar.

7. Adjust fuel/air mixture. Guide Special Tool 9187 into adjusting bore of heated wire air flow sensor and turn idle speed potentiometer accordingly.

Turning clockwise = richer mixture. Turning counterclockwise = leaner mixture.

CO specifications: 0.5 - 1.5 % R. o. W. 0.5 - 1.0 % Australia,

Switzerland, Sweden

8. Remove plug in air pipe and reconnect hose.



1. Remove air intake hoses.

2. Take off upper air cleaner housing and remove hose on blowoff switching valve.

2. Insert heated wire air flow sensor that access to adjusting bore for idle speed potentiometer with Special Tool 9187 is guaranteed.

Align air flow sensor if necessary.

3. Unscrew unlosable hexagon head screws (13 mm wrench size) in lower air cleaner housing and remove lower housing with heated wire air flow sensor.

4. Pull off both multiple pin plugs.

Starter Mounting Housing For Porsche 928

3. Install and mount lower air cleaner housing and then tighten bottom hose clamp.

5. Loosen bottom hose clamp and take heated wire air flow sensor off of lower air cleaner housing.


1. Check 0- ring in air guide housing for damage and correct fit. Lubricate 0 ring with silicone grease, e. g. Bosch Ft 2v2.

Was this article helpful?

0 0
Porsche Classic Models

Porsche Classic Models

The History of Porsche Cars through its generational changes. A must have ebook for any Porsche fanatic, this ebook is a reference book for Porsche enthusiasts. Discover all there is to know about the greatest Porsches ever made. All models are fully described and illustrated providing a definitive production history plus an accurate guide to original specs and equipment.

Get My Free Ebook