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Engine Controls - Adjustments Porsche 911 Turbo 993

Adjustments 3 illustrations ~418 words

INTRODUCTION

Note. Introduction information not applicable.

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

VALVE CLEARANCE

Note. Hydraulic lifters are used. No adjustments are required.

IGNITION TIMING

Ignition timing is controlled by Digital Motor Electronics (DME) engine management system and is not adjustable. Specifications given in the IGNITION TIMING is for verification purpose only. (Scheme 1)

ApplicationDegrees @ RPM
Automatic TransmissionTDC +/- 3 @ 710-790
Manual TransmissionTDC +/- 3 @ 760-840

IGNITION TIMING

Scheme 1

Scheme 1

COLD (FAST) IDLE

Fast idle speed is controlled by Digital Motor Electronics (DME) engine management system and is not adjustable.

IDLE SPEED & MIXTURE

Note. After disconnecting battery or DME control unit, the engine MUST be run at idle for at least 10 minutes before idle speed and CO level can be rechecked.

Idle speed and mixture are controlled by Digital Motor Electronics (DME) engine management system and are not adjustable. Values given in IDLE SPEED & CO LEVEL are for verification purpose only.

Application(1) Idle RPM(2) CO Level
Automatic Transmission710-7900.4-1.2 %
Manual Transmission760-8400.4-1.2 %
(1) Idle RPM is controlled by DME and is not adjustable. (2) With oxygen sensor connected. Measurement is taken in front of catalytic converter. Hydrocarbon level should be equal to or less than 300 parts per million (ppm).
(1)Idle RPM is controlled by DME and is not adjustable.
(2)With oxygen sensor connected. Measurement is taken in front of catalytic converter. Hydrocarbon level should be equal to or less than 300 parts per million (ppm).

IDLE SPEED & CO LEVEL

CLOSED THROTTLE POSITION (CTP) SWITCH

  1. Disconnect CTP switch. (Scheme 2) Using an ohmmeter, check continuity between switch terminals No. 1 and 2. (Scheme 3)
  2. With throttle valve closed, ohmmeter reading should be less than 10 ohms. Open throttle valve beyond one-degree angle. With throttle valve open, ohmmeter reading should be infinite.
  3. If ohmmeter readings are not as specified, use a 0.036" (0.90 mm) feeler gauge to adjust clearance between switch housing and drag lever when throttle valve is closed.

Scheme 2

Scheme 2

Scheme 3

Scheme 3

Manual Transmission Only

  1. Disconnect wide open (full) throttle switch. (Scheme 2) Using an ohmmeter, check continuity between switch terminals No. 2 and 3. (Scheme 3)
  2. With throttle valve closed, ohmmeter reading should be infinite. With throttle valve at least 2/3 open, resistance should be less than 10 ohms. If ohmmeter readings are not as specified, adjust switch so contacts will close at throttle angle of about 70 degrees.
ApplicationOhms
Closed Throttle Position (CTP) Switch (1)
Throttle Valve ClosedLess Than 10
Throttle Valve Open (2)Infinite
Throttle Valve Potentiometer (3)
Throttle Valve Closed (Idle)0.5
Throttle Valve Open (Full Throttle)4000
Wide Open (Full) Throttle Switch (4)
Throttle Valve ClosedInfinite
Throttle Valve Open (5)Less Than 10
(1) Measure between terminals No. 1 and 2. (Scheme 3) (2) Throttle valve angle opening is greater than one degree. (3) Check potentiometer resistance between terminal No. 2 (Green/Yellow wire) and terminal No. 3 (Brown wire). (4) Measure between terminals No. 2 and 3. (Scheme 3) (5) Throttle valve must be at least 2/3 open.
(1)Measure between terminals No. 1 and 2. (Scheme 3)
(2)Throttle valve angle opening is greater than one degree.
(3)Check potentiometer resistance between terminal No. 2 (Green/Yellow wire) and terminal No. 3 (Brown wire).
(4)Measure between terminals No. 2 and 3. (Scheme 3)
(5)Throttle valve must be at least 2/3 open.

THROTTLE VALVE SWITCH RESISTANCE

Tiptronic (Automatic Transmission Only)

  1. Adjust throttle valve potentiometer, also known as Throttle Position (TP) sensor, so that click is heard when small diameter throttle valve plate begins to open. DO NOT confuse throttle valve potentiometer adjustment click with click produced by Closed Throttle Position (CTP) switch contacts.
  2. With ignition off, disconnect throttle valve potentiometer. Check potentiometer resistance between terminal No. 2 (Green/Yellow wire) and terminal No. 3 (Brown wire). Resistance should vary from 0.5 ohms at idle to 4000 ohms at full throttle. If resistance is not as specified, replace throttle valve potentiometer.

Poses Online

See also:
IGNITION TIMING