Fuel Injection System - Bosch Cis-E Audi 5000 S

INTRODUCTION

Note. Some 1987 5000S and Coupe GTs have the 2.3L engine equipped with CIS-E III. Refer to the CIS-E III article in FUEL or COMPUTER CONTROLS sections.

DESCRIPTION

Bosch CIS-E exhaust emission system uses CIS (Continuous Injection System) for fuel delivery and electronic controls for mixture adjustment.

Mechanical portion of CIS-E system consists of Mixture Control Unit (MCU), diaphragm pressure regulator, auxiliary air regulator, cold start valve, fuel injectors, fuel pump and filter. The MCU is comprised of the airflow sensor and fuel distributor.

Electronic controls consist of airflow sensor position indicator (potentiometer), differential pressure regulator, thermo time switch, coolant temperature sensor, Electronic Control Unit (ECU), Transistor Controlled Ignition (TCI), knock sensor, knock sensor control unit, throttle valve microswitch, altitude (barometric) sensor, lambda control and oxygen sensor.

If partial system failure occurs, the ECU will switch to a back-up or "limp-home" mode to allow vehicle operation until system can be repaired.

Bosch CIS-E Component Diagram. Scheme 51

FUEL SUPPLY

CIS-E FUEL PUMP LOCATIONS

Fuel Pump & Relay

The fuel pump assembly, is equipped with a pressure damper at the suction end. Mounting location varies with model and manufacturer. Fuel pump is activated during start-up and when engine is running. Fuel pump relay switches off fuel pump in absence of signal from ignition control unit and provides voltage for oxygen sensor heating element.

Mixture Control Unit (MCU)

Fuel is metered and delivered to individual cylinders dependent on air intake quantity which is metered by airflow sensor. MCU consists of fuel distributor with differential pressure regulator and airflow sensor with potentiometer (sensor position indicator).

Airflow Sensor

Rest position of airflow sensor plate is angled in relation to air inlet venturi. Airflow sensor potentiometer is attached to the side of the MCU and connected to the air sensor plate actuating lever. It generates a voltage signal based on the position of the airflow sensor plate. The ECU uses this signal to adjust cold acceleration enrichment.

Fuel Distributor

The fuel distributor controls the flow of fuel to the injectors. A control plunger, operated by the airflow sensor regulates the control pressure differential between the injector supply (upper chamber) and the lower chamber (fuel return). This differential in pressure controls the amount of fuel flow to the injectors. The electrically controlled, differential pressure regulator also controls fuel flow from the lower chamber.

Differential Pressure Regulator

Differential pressure regulator is mounted on side of fuel distributor. An electrically operated plate valve combined with fixed outlet orifice, governs pressure in lower chamber. (Scheme 52) Pressure change in lower chamber causes movement of diaphragm and controls fuel volume flow to injectors.

Actuating signal comes from ECU and can range from 60 to 120 mA, depending upon engine operating conditions. With engine running, system pressure at fuel inlet is 75-82 psi (5.3-5.8 kg/cm 2 ).

Effect Of Diff Pressure Regulator Plate Position On Fuel Dist. Scheme 52

Electronic Control Unit (ECU)

The ECU of Audi models is found behind cover in front passenger footwell.

With ignition switched on, ECU is connected to battery voltage. To prevent voltage fluctuations when vehicle components are switched on, ECU is provided with voltage stabilizer circuit. Operating voltage is 8 volts.

ECU unit utilizes various input signals to control fuel delivery and control exhaust emissions. Output signals are sent to differential pressure regulator and to idle speed control valve.

Cranking Enrichment

During engine cranking, a signal from the starter relay is sent to the ECU to enrich the fuel mixture. The amount of enrichment or activation of the cold start valve is controlled by a coolant temperature sensor. When the enrichment amount is determined by the ECU it remains constant during that cranking cycle. A thermo timer controls enrichment cycle time after starting.

Warm-Up Enrichment

Fuel enrichment during warm-up is controlled by the differential pressure regulator. When cold, the signal from the coolant temperature sensor allows more current to be supplied to the pressure regulator. This will provide greater fuel enrichment.

Maximum Engine Speed Limiter

ECU senses engine speed based on impulses from terminal "TD" of ignition switching unit. Maximum engine speed is controlled by adjusting current supply to the differential pressure regulator from ECU. Lower chamber pressure in the fuel distributor is increased to limit fuel flow to the injectors. When maximum engine speed is reached a signal from the ECU will interrupt the fuel pump relay signal and shut off the fuel pump.

Altitude Correction

Injection control is influenced by altitude. With ignition switched on or with engine running, altitude sensor will receive constant voltage signal of approximately 8 volts from ECU. As altitude increases (air pressure decreases), the signal from the ECU reduces current to the differential pressure regulator. This leans out the fuel mixture.

Lambda Control

Lambda control is integrated in ECU and sensor input signals. After input signals are amplified, output signal adjust differential pressure regulator.

Control range of differential pressure regulator current is 0-16 mA. Regulator pressure change at 8 mA or above.

Lambda control is non-operational under these conditions: oxygen sensor not ready for operation or defective, during deceleration shut-off, under full load conditions, during acceleration enrichment, when starting engine at coolant temperatures below 60°F (15°C) or until coolant temperature reaches 105°F (40°C).

Oxygen Sensor

Oxygen sensor is mounted in exhaust pipe in front of catalytic converter. Oxygen sensor measures oxygen content in exhaust gas. Heating element, energized through terminal No. 87 of fuel pump relay, is used to ensure constant operating temperature of oxygen sensor. When operating temperature range, which starts at 572°F (300°C), is reached, oxygen sensor sends voltage signal to ECU. A rich mixture will send a signal in excess of .5 volt while a lean mixture will give signal of less than .5 volt.

Throttle Valve Microswitch

Throttle valve microswitch is activated by ECU with constant voltage signal of 8 volts. During deceleration, circuit to ECU is closed by microswitch.

Time period of deceleration shut-off depends upon engine coolant temperature. Injection of fuel will restart at 900 RPM if engine is at operating temperature. If coolant temperature is lower than operating temperature, injection of fuel will begin at higher speed than 900 RPM.

Throttle valve microswitch opens before throttle valve. This allows deceleration shut-off to be interrupted before throttle valve opens, preventing cut-in hesitation.

Deceleration input signals received by ECU result in change of current direction to differential pressure regulator coils. Plate valve opens and causes pressure in lower chamber to increase. Increased fuel pressure, combined with spring tension, forces diaphragm to cover injector ports in fuel distributor. This interrupts fuel supply to injectors.

Knock Sensor

The knock sensor is mounted at the front of the cylinder block. A 3 wire connector transmits signals to the knock sensor control unit and to the TCI. The sensor mounting bolt torque influences sensor function. See REMOVAL & INSTALLATION . The knock sensors signal will advance or retard ignition timing to control combustion chamber pre-ignition.

Knock Sensor Control Unit

The knock sensor control unit receives signals from the knock sensor and also a vacuum signal from the inlet manifold. It transmits signals to the TCI control unit to adjust ignition timing.

Electronic Idle Speed Control

Idle speed ECU is integrated in CIS-E ECU but is functionally separate from CIS-E. Idle speed air valve, located in throttle valve by-pass hose, receives signals from idle speed ECU.

The idle speed control system also is influenced by the airflow sensor voltage signal. The control unit measures the airflow rate. In combination with engine speed, the position of the airflow sensor potentiometer and the coolant temperature, the idle speed air valve controls the idle speed.

When ignition is switched on, idle speed ECU is energized. Electronic control system generates a frequency of 100 Hz.

Idle Speed Air Control Valve

With ignition switched off, idle speed air control valve is opened to maximum by a set of return springs. This is the same position as that of "limp-home" engine operation. With ignition on and engine off, idle speed air control valve is activated. This provides a valve opening which is determined by coolant temperature.

ECU supplies specific voltage to air control valve which determines correct opening for setting engine speed. A/C operation will also send a signal to the ECU which will modify the signal to the air control valve. Engine speed is controlled by temperature from 1000 RPM at 0°F (-20°C) to low of 720 RPM at 68°F (20°C).

Idle Speed Boost Valves

Idle speed boost valves are used on 4-cylinder Audi models. Vehicles without A/C use only one valve, called Idle Speed Boost Valve No. I. Vehicles with A/C also use second valve, called Idle Speed Boost Valve No. II.

With ignition on, constant voltage is supplied to idle speed boost valve No. I. If engine speed drops below 700 RPM, idle speed boost control (on relay board) completes ground circuit for boost valve No. I. Above 1050 RPM, control unit shuts off ground circuit to boost valve No. I.

Idle speed boost valve No. II is always grounded. When A/C is turned on, voltage is supplied to boost valve No. II.

AIRFLOW SENSOR PLATE

1. Check basic adjustment of sensor plate lever. With fuel distributor removed from airflow sensor housing, measure distance between roller on sensor plate lever and contact points of fuel distributor on top of airflow sensor housing. NOTE: Always check sensor plate lever adjustment if fuel distributor or airflow sensor has been replaced.
2. Use a depth gauge or vernier caliper for measuring distance. (Scheme 53) Distance should be.74-.75" (18.9-19.1 mm). If distance is out of specified range, correct it with adjustment of mixture screw.

Adjusting Sensor Plate Lever. Scheme 53

Centering Sensor Plate & Lever

1. Check sensor plate for centered position in airflow sensor housing . If plate binds on housing or is off-center, remove 6 mm bolt holding plate to lever. Coat bolt with locking compound and install finger tight.
2. Use Centering Gauge (US 1109) or .004" (.10 mm) feeler gauges to set plate equidistant from sensor housing. If plate cannot be centered, remove airflow sensor housing to center sensor lever.
3. Turn housing upside-down and remove bolt clamping counterweight to sensor lever. Coat bolt with locking compound and install finger tight. Center sensor plate lever in housing and tighten clamping bolt. Complete centering of plate.

Sensor Plate Rest Position

Upper edge of sensor plate must be below lower edge of sensor cone.070-.080" (1.80-2.10 mm). (Scheme 54) If rest position is incorrect, raise sensor plate. Open or close wire clip to change position of sensor plate. DO NOT bend leaf spring.

Sensor Plate Rest Position. Scheme 54

Scheme 55

1. Free play is between control piston and adjusting lever. Differential pressure regulator must have 4-16 mA current. Position of sensor plate lever must be correct. Measure free play on side of sensor cone closest to fuel distributor. (Scheme 55) (Scheme 55): Sensor Plate Free Play
2. Crank starter motor or use Jumper Switch (US 4480/3) for 10 seconds to develop fuel pressure. Lift sensor plate slightly until resistance is felt. Minimum clearance is any noticeable free play. Maximum clearance is.078" (2 mm) up to sensor cone.
3. If free play clearance is incorrect, remove fuel distributor. Check basic adjustment of sensor plate lever. Install fuel distributor and repeat free play clearance check. If still incorrect, adjust sensor plate clearance with control piston stop screw.

Sensor Plate Clearance Adjustment

1. Remove fuel distributor from airflow sensor housing. Turn distributor upside-down to access stop screw for control piston. This will adjust free play travel range of sensor plate lever.
2. Turning screw clockwise will increase clearance by keeping control piston higher in fuel distributor during operation. Turning screw counterclockwise will decrease clearance by allowing control piston to extend further out of fuel distributor during operation.
3. Adjusting stop screw 1/4 turn (90 degrees) will make .05" (1.3 mm) difference at sensor plate. Idle speed and CO (current reading) must be checked.

AIRFLOW SENSOR POTENTIOMETER

1. Check sensor plate rest position and adjust if necessary. Edge of plate closest to fuel distributor must be .069-.079" (1.75-2.05 mm) below lower edge of sensor housing venturi cone. Disconnect wiring from potentiometer. Connect Test Harness (VW 1501) to potentiometer, leaving vehicle harness plug disconnected.
2. Using Digital Multimeter (US 1119), measure resistance of potentiometer at terminals of test harness. Harness terminal No. 1 corresponds to potentiometer terminal No. 18; terminal No. 2 corresponds to potentiometer terminal No. 17; terminal No. 3 corresponds to potentiometer terminal No. 14.
3. Reading should be greater than 4000 ohms with meter between harness terminals No. 1 and 2. Reading should be less than 1000 ohms with meter between terminals No. 2 and 3. Reading should increase evenly up to 4000 ohms as sensor plate is lifted smoothly. If readings are not correct, replace potentiometer.
4. Using Sensor Plate Adjustable Holder (VW 1348/1), lift sensor plate to lower edge (fuel distributor side) of airflow sensor housing. Install potentiometer. Partially tighten screws so that adjustment is possible. Connect multimeter between test harness terminal No. 2 and ground.
5. Set multimeter on 20 DCV scale and turn on ignition. Reading should be .2-.3 volts. If not, move potentiometer until reading is correct. Tighten mounting screws. To check adjustment, lift sensor plate to stop. Reading should be 7 volts. If correct, secure mounting screws with Loctite.

THROTTLE VALVE HOUSING

Note. Stop screw is set by manufacturer and should not be moved.

If basic factory setting has been changed, turn throttle stop screw counterclockwise until there is a gap between stop and screw. Turn screw in until it just touches stop. Turn screw 1/2 turn (180 degrees) further. Check and adjust idle speed and CO.

Checking Throttle Idle Switch Adjustment. Scheme 56

Scheme 57

1. To check and adjust idle switch, loosen upper left bolt on throttle valve housing. Attach Protractor Pointer (3084) under bolt. Attach Protractor (3084) on primary throttle valve shaft, removing shaft nut if necessary. (Scheme 57) (Scheme 57): Checking Throttle Valve Idle Switch Adjustment
2. Disconnect wiring to switch. Connect ohmmeter between terminals of switch. Set protractor so pointer is on "0" degrees. Open throttle to 20 degrees and close it slowly. Switch must have continuity from one degree to 2.5 degrees when opening.
3. If reading is incorrect, remove throttle valve housing. Loosen idle switch mounting screws and adjust switch position. (Scheme 58) Switch must close (continuity) before throttle control reaches idle stop position.

Idle Switch Adjustment. Scheme 58

Full Throttle Switch

1. Attach protractor pointer to upper left bolt on throttle valve housing. Attach protractor to secondary throttle valve shaft. Remove shaft nut if necessary. Disconnect throttle switch wiring. Connect ohmmeter between switch terminals. (Scheme 51)
2. Set secondary throttle plate in full open position and move protractor until pointer is on "0" degrees. Allow secondary throttle valve to close about 30 degrees and reopen to full throttle position.
3. Ohmmeter must read zero ohms at 8-12 degrees before full throttle. Loosen mounting screws and adjust switch. Reading must be zero ohms (continuity) at full throttle position.

Adjusting Full Throttle Switch. Scheme 59

System Pressure

1. Check and note existing pressure. Remove pressure regulating valve from fuel distributor. (Scheme 60)
2. Adjust pressure by changing shims in shim stack. Add shims to raise system pressure. Remove shims to lower system pressure.
3. A shim change of.020" (.5 mm) will change system pressure approximately 4.2 psi. (.3 kg/cm 2 ). Ensure any replacement shims are identical in diameter to existing shims.

Adjusting System Pressure. Scheme 60

Thermo Time Switch

1. Check thermo time switch at connector on cold start valve when engine coolant temperature is less than 86°F (30°C). Disconnect and ground high tension lead at distributor cap end.
2. Disconnect connector from cold start valve. Connect test light across 2 terminals of cold start connector. Crank starter motor for 10 seconds. Test light must light up for 1-8 seconds, depending upon temperature. Thermo time switch cut-off temperature rating is stamped on switch.

Cold Start Valve

1. Check cold start valve with engine coolant temperature below 86°F (30°C). Disconnect and ground high tension lead at distributor cap end. Remove cold start valve from intake manifold with wiring and fuel line connected. Point tip into safe container.
2. Crank starter for 10 seconds. Valve should emit coneshaped spray for time allowed by thermo time switch. Dry off tip and check for leaks. Acceptable leakage rate of cold start valve is one drip per minute or less.

Auxiliary Air Valve

1. Engine coolant must be below 86°F (30°C) for cold condition testing. Ignition must have been off so element in regulator has not been warmed up. Disconnect wiring connector from air regulator. Start cold engine and let it idle. Measure voltage across connector terminals. Voltage must be 11.5 volts.
2. Pinch either regulator hose. If idle does not decrease, replace auxiliary regulator. Attach wiring to regulator. Allow engine to idle for a minimum of 5 minutes. Pinch either regulator hose. If idle speed changes replace auxiliary air valve.

1. Connect Pressure Gauge (VW 1318) between line from fuel distributor to cold start valve and test port connection on lower chamber of fuel distributor, using Adapter Fittings (VW 1318/5). Test port is sealed by a threaded plug. Bridge fuel pump relay with Jumper Switch (US 4480/3).
2. Disconnect wiring from differential pressure regulator. Open valve on pressure gauge (points at cold start valve line when open) and activate fuel pump. System pressure must be 68-78 psi (4.7-5.4 kg/cm 2 ). If pressure reading is low and fuel pump delivery quantity is good, replace pressure regulator.
3. If pressure reading is high, disconnect fuel tank return line from diaphragm pressure regulator. Repeat test. If reading is correct, check for plugged return line. If reading is incorrect with line open, replace diaphragm pressure regulator.
4. If pressure is not within specification and pressure regulator valve has been replaced adjust system pressure at fuel distributor. Refer to SYSTEM PRESSURE under «ADJUSTMENTS»(/audi/5000-s/1987-1988/remont/testing-diagnostics/#fuel-injection-system-bosch-cis-e) .

Differential (Control) Pressure

1. Close valve on pressure gauge. Activate fuel pump with jumper switch. Leave differential pressure regulator disconnected. Differential pressure reading should be 2.9-7.0 psi (.2-.5 kg/cm 2 ) less than system pressure. If pressure is incorrect, disconnect lower chamber return line and measure volume.
2. Close open port to diaphragm pressure regulator. Activate fuel pump with jumper switch. Fuel volume should be .14-.16 qts. (.13-.15L) for period of one minute. If volume is correct, replace differential pressure regulator. If volume is incorrect, replace fuel distributor.
3. Close valve on pressure gauge. Install Test Harness (1315A/1) between differential pressure regulator and vehicle harness. Set multimeter to DCA 200 mA scale. Connect multimeter to test harness. Disconnect wiring to coolant temperature sensor. Connect 15,000-ohm side of Test Resistor (VW 1490) to sensor wiring.
4. Turn on ignition and fuel pump. Differential pressure should be 10-17.5 psi (.7-1.2 kg/cm 2 ) less than system pressure. Differential pressure regulator current should be 50-80 mA. If pressure is incorrect and current is correct, replace differential pressure regulator.
5. If both pressure and current readings are incorrect, remove test harness from differential pressure regulator. Check resistance of differential pressure regulator, which should be 17.5-21.5k ohms. If reading is incorrect, replace differential pressure regulator.
6. If reading is correct, check ground from temperature sensor to cold start valve. If ground is good, check power supply fuse. If fuse is okay, check terminals on ECU connector. If connector is okay, replace ECU.

Residual Pressure & Internal Leak Testing

1. Open valve on pressure gauge. Operate fuel pump for 30 seconds. Pressure can drop to a minimum of 38 psi (2.7 kg/cm 2 ) after 10 minutes. If pressure drops below specification, inspect fuel pump check valve and all fuel fittings for leakage. NOTE: Pressure and leak testing does not include checking cold start valve.
2. If there are no leaks, check sensor plate clearance. If plate clearance is correct, replace diaphragm pressure regulator and repeat leak test. If pressure drop is not within specification, replace fuel distributor "O" rings.

Main Pump Delivery Volume

1. Check transfer pump (if equipped) and fuel filter. Disconnect fuel return line and place open end in measuring container. Switch on fuel pump with jumper switch. Check fuel pump delivery volume for 30 second period. Delivery rates are given with voltage reading at pump as volume will change with different voltages.
2. Minimum delivery volume for all Audi models is .71 qts. (.68L) for 30 seconds with reading of 11.4 volts at fuel pump.

Scheme 61

1. Remove fuel pump relay, from relay panel, and install Jumper Switch (US 4480/3) in off position in place of relay. Attach Fuel Quantity Analyzer (US 4480) to bumper and secure in place. Remove injectors from cylinder head with fuel lines attached. Check and replace fuel injector "O" rings as necessary.
2. Check tightness of injector insert (2-piece inserts). If inserts are loose, remove and clean threads. Use sealing compound when installing upper insert. Replace sealing washer that goes against cylinder head below lower portion of insert. Lubricate injector "O" rings with gasoline and install injectors, with fuel lines connected, into fuel quantity analyzer tubes.
3. Ensure lines are not kinked or bent. Loosen fittings to align fuel lines and retighten. Remove rubber boot from airflow sensor housing above sensor plate. Turn and lift setting screw and adjusting slide of Sensor Plate Adjustable Holder (VW 1348/1) into upper position. This simulates full throttle operation. (Scheme 61) (Scheme 61): Sensor Plate Adjustable Holder (VW 1348/1) Pointer must face toward center of fuel distributor.
4. Place sensor plate adjustable holder on airflow sensor housing with holder centered over plate. Pointer on edge of holder base must point toward center of fuel distributor. Push adjusting slide of holder down onto stop.
5. Turn adjusting screw clockwise until magnetic end touches sensor plate retaining bolt. Activate fuel pump with jumper switch. Turn adjusting screw of holder counterclockwise until any one injector starts to deliver fuel. Turn off jumper switch and empty fuel quantity analyzer into fuel tank.
6. Idle injection quantity is measured first. Lifting adjusting slide of holder to first stop simulates idle position of sensor plate. Activate fuel pump with jumper switch until fuel level reaches 20 ml on scale of any tube for quantity comparison.
7. Check that all injectors have identical spray patterns that are even and cone-shaped. If not, raise sensor plate up quickly to full lift position and release. Repeat idle quantity test. Compare amounts of fuel delivered by all injectors with analyzer held level. Maximum difference in delivery quantity between injectors is 3.0 ml of fuel.
8. If fuel delivery quantity differs between high and low levels by more than 3.0 ml, interchange injectors and repeat test. If difference of delivery quantity changes with injectors, replace injectors. If difference of delivery quantity does not change with movement of injectors, either fuel lines are pinched or fuel distributor is defective.
9. Measure full throttle injection quantity. Empty analyzer into fuel tank and reinstall injectors in analyzer. Lift adjusting slide of holder to last stop to simulate full throttle position of sensor plate. Activate fuel pump with jumper switch until fuel level reaches 80 ml on scale of any tube of analyzer.
10. Check that all injectors have identical spray patterns that are even and cone-shaped. If not, raise sensor plate up quickly to full lift position and release. Repeat full throttle quantity test. Compare amounts of fuel delivered by all injectors with analyzer held level. Maximum difference in delivery quantity between injectors is 8.0 ml of fuel.
11. If fuel delivery quantity differs between high and low levels by more than 8.0 ml, interchange injectors and repeat test. If difference of delivery quantity changes with injectors, replace injectors. If difference of delivery quantity does not change with movement of injectors, either fuel lines are pinched or fuel distributor is defective.
12. Check fuel injectors for leakage immediately after delivery quantity test is complete. Set sensor plate in rest position. Activate fuel pump with jumper switch for 2 minutes. Injectors should not drip. Replace injectors that do drip.

ELECTRICAL COMPONENTS

Note. For complete information on electrical components and testing see COMPUTERIZED ENGINE CONTROL article.

Removal

1. Disconnect battery and remove air cleaner. Disconnect all fuel and injector lines from fuel distributor. Plug fuel supply and return lines. Catch any fuel spillage with rag.
2. Disconnect wiring from differential pressure regulator. Remove screws holding fuel distributor to airflow sensor housing. Remove fuel distributor by turning back and forth while lifting up.

Installation

1. Lightly lubricate new sealing "O" ring and mount on fuel distributor. Install fuel distributor. Ensure "O" ring is not damaged or air leaks will result. Connect all fuel lines except those to fuel injectors. Check sensor plate adjusting lever and fuel distributor control piston for smooth operation.
2. Remove fuel pump relay and bridge fuel pump circuit. Use Jumper Switch (US 4480/3) in place of fuel pump relay. When pressure has built up, turn off fuel pump. Move sensor plate from rest position to end of travel.
3. Uniform resistance should be felt during entire movement. No resistance should be felt on quick return to rest position. Connect injector lines. Install fuel pump relay. Start engine and check complete fuel system for leaks.

Remove injectors from inserts in head with fuel lines attached. Using 13 mm hex head socket, remove inserts from head. Use 2 wrenches to remove injectors from lines.

To install, reverse removal procedures. Use 2 wrenches when tightening injector lines to injectors. Always use new "O" rings and lubricate them to ease installation. On Audi models with 2-piece inserts, replace insert sealing washer (against head) and use sealing compound on upper insert threaded portion.

1. Disconnect accelerator cable from linkage. Disconnect return spring on throttle valve housing. On vehicles with cruise control, remove connecting rod on throttle valve housing. Pull off vacuum hoses for ignition advance and fuel evaporation system purge line. Remove nuts holding throttle valve housing to airflow sensor housing.
2. Disconnect throttle valve switch. Remove 2 nuts holding throttle valve housing to metallic front vibration mounts. Disconnect fuel return hose from diaphragm pressure regulator. Lift sensor housing upward and remove throttle valve housing. Remove gasket between intake manifold and throttle valve housing.

To install, reverse removal procedure. Use new gasket. Adjust accelerator linkage and idle speed.

Remove air filter and unscrew stop bracket. Heat fastening bolt for airflow sensor plate with hot air blower to loosen locking compound. Remove bolt carefully to ensure threads are not damaged. Use a 6 mm tap to clean out threads for airflow sensor plate fastening bolt.

Insert airflow sensor plate (identified by 5 punch marks) in upward direction. Lightly tighten self-locking screw. Check that sensor plate is centered and rest position is correct. See ADJUSTMENTS . To complete installation, reverse removal procedure.

Removal & Installation

Remove diaphragm pressure regulator. Remove insulating compound to uncover screws holding potentiometer to housing. Remove potentiometer. Do not touch or damage slide contact and conductor. To install, reverse removal procedure. Adjust potentiometer. See ADJUSTMENTS .

1. The knock sensor is attached at the front of the engine block. There are 2 types of sensors. The Type I sensor has its cable connection molded off center from the side of the sensor. No washers are used on fastening bolt. Tighten to 7-9 ft. lbs. (10-12 N.m).
2. The Type II sensor has its connector cable molding centered on the side of the connector. It is tight end to 11-18 ft. lbs. (15-25 N.m) without washers.

CIS-E Wiring Diagram (4000S & 4000S Quattro - 4 & 5-Cylinder). Scheme 62

CIS-E Wiring Diagram (5000S). Scheme 63

CIS-E Wiring Diagram (5000CS - Turbo & Quattro). Scheme 64

See also:
• REMOVAL & INSTALLATION
• ADJUSTMENTS