Adjusting Idle Without Catalytic Converter

87 MODELS ONWARD ENGINE TYPE M28. 41/42 Note:

No provision is made for adjusting the idle speed. The adjustment at the throttle nozzle is no longer necessary^ __

Idle Speed C 0 -Level Adjustment

Precondition for adjustment:

Engine in perfect mechanical order. Switch off all consumers during adjustment. Make adjustments as quickly as possible to avoid excessive heat at intake ports which would result in incorrect CO readings. Intake air temperature 15 - 35°C.

1.Disconnect additional air pump hose at changeover valve and seal changeover valve with a suitable plug.

2.Reconnect air intake hose

3.Run engine to operating temperature (70-90°C oil temperature). Use oil temperature meter, special tool 9122 +9122/2.

Mercruiser Idle Mixture Adjustment Tool

4.Check CO-level. If the CO-level is not within specified limits, correct setting of CO-potentiometer. Remove plug covering hole which provides access to CO-adjustment.

Porsche 928 Oil Pan Removal Instructions

Specified CO-value: 0.5 - 1.5% Turning clockwise = richer mixture Turning anticlockwise = leaner mixture

24 - 214 Adjusting Idle Without Catalytic Converter

5.Insert plug (blue) spare part No. 944 606 935 01 in CO-adjustment screw apperture.

Recheck idle speed

Connect separate rev. counter in accordance with manufacturer's instructions

Idle speed 675 + 25 rpm

Printed in Germany - XVI, 1987 Adjusting Idle without Catalytic 24 - 215

Converter

FUEL PATH - LH-JETRONIC 928 S, 87 MODELS ONWARD ENGINE TYPE M28. 41/42

Fuel Adjust Porsche 928s

24 - 216 Fuel path, LH-Jetronic

Printed in Germany

FUEL PATH - LH-JETRONIC 928 S, 87 MODELS ONWARD ENGINE TYPE M28.41/42

2 - Fuel filter

4 - Distributor-type fuel-injection tubes

5 - Injectors

A - Throttle housing B - Idle speed actuator C - Intake jet pump D - Pressure damper E - Pressure regulator F - Vacuum valve

G - Electric tank breather valve H - Oil filler neck I - Secondary-air valve

K - Vacuum-operated switch valve (tune-intake flap) L - Vacuum unit (tune-intake flap)

a - from fuel tank b - to fuel tank c - from activated charcoal cannister d - from vacuum reservoir e - to automatic transmission

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