Fuel Injection System - Bosch Cis-E Audi 4000 CS Quattro

DESCRIPTION

Bosch CIS-E fuel injection uses basic CIS (continuous injection system) for fuel delivery and electronic controls for mixture correction functions.

Mechanical portion of CIS-E system consists of mixture control unit (airflow sensor and fuel distributor), diaphragm pressure regulator (system pressure regulation), auxiliary air regulator (throttle by-pass), cold start valve, fuel injectors, fuel pump and filter.

Electronic controls consist of airflow sensor position indicator (potentiometer), differential pressure regulator, thermo time switch, coolant temperature sensor, electronic control unit (ECU), transistorized ignition switching unit, throttle valve microswitch, altitude (barometric) sensor, lambda control and oxygen sensor.

If ECU malfunctions, CIS-E system will operate in back-up or "limp-home" mode until system can be repaired.

Bosch CIS-E Component Diagram. Scheme 2

Fuel Pump & Relay

Roller-cell fuel pump assembly, with damper at suction end, is found in several locations in vehicle depending upon manufacturer. Fuel pump relay activates fuel pump during starting and with engine running. It also switches off fuel pump in absence of TD signal from ignition control unit and provides voltage supply for oxygen sensor heating.

On Coupe GT and 4000S, pump, accumulator and filter are located in right rear area. On 4000S Quattro, pump, accumulator and filter are located in left rear area. On 5000S, fuel pump is located in fuel tank underneath sending unit; gravity vent valve is incorporated into sending unit.

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

Basic mechanical operating principle remains unchanged. Rest position of airflow sensor plate is no longer horizontal. It now angles upward with corresponding tilt of air cone. Airflow sensor potentiometer is bolted on. Air guide housing is bolted to airflow sensor from below.

Fuel Distributor

Fuel distributor has been changed from previous CIS units. System pressure regulator piston and pressure compensating valve have been deleted. Differential pressure adjusting screws and compression springs have been moved to lower chamber. Additional strainer is installed in front of differential pressure valve. Pressure on top of control piston is equal to system pressure. Fuel supply, return, and cold start valve lines are arranged differently. These connections vary depending upon engine or manufacturer applications.

Differential Pressure Regulator

Differential pressure regulator is bolted onto side of fuel distributor. Plate valve position in relation to inlet of pressure regulator can be varied electrically. Plate position, combined with fixed outlet orifice, governs pressure in lower chamber. (Scheme 3)

Actuating signal comes from ECU and can range from 60 to 120 mA, depending upon engine operating conditions. With engine running, constant system pressure of 75-82 psi (5.3-5.8 kg/cm 2 ) is applied at fuel inlet. Plate valve position is governed by current intensity. Corresponding pressure change in lower chamber causes movement of diaphragm and influences fuel volume flowing to injectors.

Effect Of Differential Pressure Regulator Plate Position On Fuel Distributor Note pressure control valve reaction to plate position. Scheme 3

Electronic Control Unit (ECU)

The ECU is found behind cover in front passenger footwell. Ambient temperature around ECU must not exceed 180°F (85°C).

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 correction circuit. Operating voltage is 8 volts.

ECU unit utilizes various input signals for control of fuel delivery and exhaust emissions. Input signals are converted into corresponding current values and sent to differential pressure regulator and to idle speed air valve.

Cranking Enrichment

During cranking, enrichment signal is provided via terminal No. 50. Amount of enrichment depends on coolant temperature. Timing element regulates enrichment after one second to basic warm-up value plus any after-start increase. Basic warm-up value remains constant during cranking procedure.

After-Start Enrichment

This process allows smooth running characteristics immediately after starting. When cranking is stopped, regulation of after-start enrichment begins. Enrichment will drop to basic warm-up value, which varies with temperature. Amount and duration of after-start enrichment depends on coolant temperature.

Warm-Up Enrichment

Fuel enrichment depends on coolant temperature. Lower coolant temperature results in higher current at actuator. This will provide greater fuel enrichment.

Maximum Engine Speed

ECU senses engine speed based on impulses from terminal "TD" of ignition switching unit. Engine speed is limited by changing current to differential pressure regulator from ECU. Lower chamber pressure is increased to system pressure and fuel supply to injection valves is interrupted.

Maximum RPM Cut-Off

If the fuel pump relay receives the number of impulses corresponding to the maximum engine RPM, the contact between the fuel pump and fuel pump relay is turned off.

Altitude Correction

Fuel injected is based on signal from altitude sensor. 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), mixture will be changed by reduction of differential pressure regulator current.

Lambda Control

Lambda control is integrated in ECU and monitors input signals from sensors. After input signals are amplified, output signals for differential pressure regulator are determined.

Control range of differential pressure regulator current is 0-16 mA. Mean value at which control takes place is 8 mA.

Lambda control is made inoperative by signal from ECU under these conditions: oxygen sensor not ready for operation or defective, during deceleration shut-off, under full load conditions, during acceleration enrichment or when starting engine at coolant temperatures below 60°F (15°C) 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. Rich mixture will give a signal of more than .5 volt while lean mixture will give signal of less than .5 volt.

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.

Functions of the idle speed control system are extended by the air flow sensor voltage signal. As a result, the control unit recognizes the momentary airflow rate. In combination with the engine speed, the position of the microswitch and the coolant temperature, the activation of the idle speed air valve and thereby the idle speed will be determined.

When ignition is switched on, idle speed ECU is energized. Electronic control system will generate basic frequency of 100 Hz.

Idle Speed Air 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 emergency engine operation. With ignition switched on and engine off, idle speed air control valve is activated by specific voltage. This provides valve opening which is dependent upon coolant temperature.

ECU supplies specific voltage to air control valve which determines correct opening for setting engine speed. A/C operation will also cause change in signal to air control valve. Nominal speed is controlled depending on temperature in range between high of 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 vehicles. 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.

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.

AIRFLOW SENSOR PLATE

Basic Plate Lever Adjustment

Note. Always check basic sensor plate lever adjustment if fuel distributor or airflow sensor has been replaced.

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.
2. Use depth gauge or vernier caliper for measuring distance. (Scheme 4) Distance should be.74-.75" (18.9-19.1 mm). If distance is out of specified range, correct it with adjustment of mixture screw.

Basic Adjustment Of Sensor Plate Lever. Scheme 4

Centering 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 by distance of.07-.08" (1.8-2.1 mm). (Scheme 5) 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 Distance from cone edge to plate is .07-.08" (1.8-2.1 mm). Scheme 5

Sensor Plate Free Play

1. Free play is between control piston and adjusting lever. Differential pressure regulator must have 4-16 mA current. Basic adjustment of sensor plate lever must be correct. Measure free play on side of sensor cone closest to fuel distributor. (Scheme 6) (Scheme 6): Sensor Plate Free Play Check basic adjustment of sensor plate lever first.
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 feeling some 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 not correct, 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 move 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. Stop screw movement of 1/4 turn (90°) will make .05" (1.3 mm) difference at sensor plate. Idle speed and CO (current reading) must be checked and adjusted.

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, tightening screws so that adjustment is possible. Connect multimeter between test harness terminal No. 2 and ground.
5. Set multimeter on 20-volt DC scale and turn on ignition. Reading should be .2-.3 volts. If not, move potentiometer until reading is correct. If correct, tighten mounting screws. To check adjustment, lift sensor plate to stop. Reading should be 7 volts. If correct, secure mounting screws with Loctite on heads.

THROTTLE VALVE HOUSING

If basic factory setting has been changed, turn throttle stop screw counterclockwise until there is a gap between stop and screw. Place thin paper between screw and stop. Turn screw in while moving paper back and forth. When screw pinches paper, turn screw 1/2 turn (180°) further and remove paper. Check and adjust idle speed and CO.

Scheme 6

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. see scheme 6 see scheme 6: Checking Throttle Valve Idle Switch Adjustment Ohmmeter MUST read zero ohms before idle position is reached.
2. Disconnect wiring to switch. Connect ohmmeter between terminals of switch. Set protractor so pointer is on 0°. Open throttle to 20° and close it slowly. Reading must be zero ohms (continuity) from 1° to 2.5° positions.
3. If reading is not correct, remove throttle valve housing. Loosen idle switch mounting screws and adjust switch position. (Scheme 7) Ohmmeter must show zero ohms (continuity) before throttle reaches idle stop position.

Idle Switch Adjustment Switch must close before throttle reaches idle stop position. Scheme 7

Full Throttle Switch

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

Adjusting Full Throttle Switch Ohmmeter MUST read zero ohms at full throttle position. Scheme 8

Note. For all adjustments not covered in this article, see TUNE-UP article in the TUNE-UP section.

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 wire plug from cold start valve. Connect test light across 2 terminals of cold start connector. Crank starter motor. 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 cone-shaped spray for time allowed by thermo time switch. Dry off tip and check for leaks. If cold start valve drips within one minute, replace valve.

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 from air regulator. Start cold engine and let it idle. Pinch either regulator hose. If idle does not decrease, replace auxiliary regulator.
2. Engine oil temperature must be above 176°F (80°C) for warm condition testing. Attach wiring to regulator. Start engine and run until at operating temperature. Pinch either regulator hose. If idle speed does change, check voltage supply to air auxiliary regulator.

FUEL DELIVERY & SYSTEM PRESSURES

Note. System pressure is not adjustable.

System Pressure

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 has threaded plug closing it. 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 75-82 psi (5.3-5.8 kg/cm 2 ). If pressure reading is low and fuel pump delivery quantity is good, replace diaphragm 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 not correct with line open, replace diaphragm pressure regulator.

Lower Chamber (Differential) Pressure - Part I

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 not correct, disconnect lower chamber return line and hold open end over measuring container.
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 not correct, replace fuel distributor.

Lower Chamber (Differential) Pressure - Part II

1. Close valve on pressure gauge. Install Test Harness (1315A/1) between differential pressure regulator and vehicle harness. Set multimeter to DCA 200 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.
2. 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.
3. If both pressure and current readings are incorrect, remove test harness from differential pressure regulator. Check resistance of differential pressure regulator, which should be 17.5-21.5 ohms. If reading is incorrect, replace differential pressure regulator.
4. If reading is correct, check ground from temperature sensor to cold start valve. If ground is good, check power supply fuse. If fuse is good, check terminals on ECU connector. If connector is good, replace ECU.

Residual Pressure & Internal Leak Testing

Note. Pressure and leak testing does not include checking cold start valve.

1. Open valve on pressure gauge. Turn on fuel pump for 30 seconds and then turn it off. Pressure can drop to a minimum of 38 psi (2.7 kg/cm 2 ) after 10 minutes. If pressure drops too far, inspect fuel pump check valve and all fuel fittings for leakage.
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 still drops too far, 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 minimum 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 is .71 qts. (.68L) for 30 seconds with reading of 11.4 volts at fuel pump. Voltage is measured with engine off and fuel pump activated by jumper switch.

1. Remove fuel pump relay 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 properly and then tighten fittings. 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. see scheme 9 see scheme 9: 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 so that holder is 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 setting 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 analyzing.
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. Full throttle injection quantity is measured next. 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. Good injectors will not drip. Replace any injectors that do drip.

System Testing

Following VOLTAGE CHECKS and RESISTANCE CHECKS charts show procedure for checking CIS-E system components from ECU connector. ECU connector terminal numbers are called out in testing procedures. Ignition MUST be off whenever ECU connector is disconnected or reconnected. Use care to avoid any terminal damage when testing, removing or attaching connectors.

Always check all connections used in test procedure. If readings are incorrect, disconnect terminals and determine if wiring or components are at fault. High tension lead should be disconnected at ignition distributor end and connected to ground. Use Digital Multimeter (US 1119).

5000S 5-CYLINDER VOLTAGE CHECKS (1)

5000S 5-CYLINDER RESISTANCE CHECKS (1)

4000S 4-CYLINDER VOLTAGE CHECKS (1)

4000S 4-CYLINDER RESISTANCE CHECKS (1)

Fuel Pump Relay - 5000S

Note. No testing procedure is available for Coupe GT, 4000S or 4000S Quattro.

1. Remove fuel pump relay from relay board. Turn ignition on. Test light should light when connected between socket for relay terminal No. 46 and ground.
2. While starter motor is operating, test light should flicker when connected between sockets for relay terminals No. 50 and 51. Test light should light when connected between sockets for relay terminals No. 46 and 50. Test light should light when connected between sockets for relay terminals No. 46 and 52.
3. If test light does not light up for all tests, check for break in wiring circuits. If test light does light up for all tests but there is no voltage at fuel pump with relay installed, replace fuel pump relay.

Connect test harness between differential pressure regulator and vehicle harness. (Scheme 9) Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor and leave open. Turn ignition on. Differential pressure regulator current should be 80-110 mA. If not, replace ECU.

Connecting Multimeter to Differential Pressure Regulator This shows connections for all enrichment tests. Scheme 9

Cold Acceleration Enrichment

1. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor and leave open. Remove intake air boot.
2. Turn ignition on and lift sensor plate quickly to full open position. Differential pressure regulator current should increase to more than 110 mA, then drop back to 80-110 mA range. If not, check potentiometer and wiring to ECU. If potentiometer and wiring are good, replace ECU.

1. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor and leave open. Ground high tension lead (terminal No. 4) from ignition distributor.
2. Crank starter for 3 seconds. Let key return to "ON" position. Differential pressure regulator current reading should increase to more than 120 mA for 20-50 seconds, then return to 80-110 mA range.
3. If not, check starter signal to terminal No. 24 of ECU connector. Check signal from relay board to starter motor (terminal No. 15a on starter). On 5-cylinder vehicles, check voltage between ECU terminals No. 2 and 21. See VOLTAGE CHECKS and RESISTANCE CHECKS CHARTS for appropriate testing procedure. If all wiring is good, replace ECU.

Starting Enrichment - 5-Cylinder

1. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor. Plug jumper end of Test Resistor (VW 1490) into harness connector of temperature sensor. Activate starter for 3 seconds.
2. Current reading should be more than 70 mA for first 1.5 seconds of starter operation. If not, check for open circuit between terminal No. 24 on ECU connector and terminal No. 15a on starter. If starter circuit is good, check between terminals No. 2 and 21 on ECU connector. If wiring is good, replace ECU.

Full Throttle Enrichment

1. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor. Plug jumper end of test resistor into harness connector of temperature sensor. Unplug oxygen sensor. Turn ignition on.
2. Turn full throttle switch on completely. Current reading should increase 3 mA when switch is activated. If not, check full throttle switch. See «ADJUSTMENTS»(/audi/4000-cs-quattro/1986-1987/remont/testing-diagnostics/#fuel-injection-system-bosch-cis-e) .
3. If switch is good and adjusted properly, check for open circuit between terminals No. 5 and 2 on ECU connector and terminals on full throttle switch. If wiring is good, replace ECU.

Deceleration Fuel Shut-Off Check

1. Engine oil temperature must be at minimum of 120°F (50°C). Reconnect wiring to temperature sensor. Start engine and run it at 2000 RPM briefly. Release throttle.
2. Differential pressure regulator current reading should briefly go into negative (-30 to -60 mA). If not, check for open idle switch signal at ECU connector terminals No. 2 and 13. If switch is good, replace ECU.

Altitude Sensor

Note. Testing altitude sensor should be done if differential pressure regulator current readings are incorrect based upon altitude.

1. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor and leave unplugged. Replace fuel pump relay with Jumper Switch (US 4480/3) in off position.
2. Disconnect wiring from altitude sensor. Activate fuel pump and turn on ignition. Differential pressure regulator current reading should be 8-12 mA. Bridge terminals No. 1 (signal) and 2 (+/power) of altitude sensor connector with jumper wire. Differential pressure regulator current reading should be 11-14 mA.
3. Bridge terminals No. 1 and 3 (-/ground) of altitude sensor connector. Differential pressure regulator current reading should be 0-4 mA. If readings are correct, replace altitude sensor and reset CO. If readings are incorrect, check for open circuit between altitude sensor and ECU. If wiring is good, replace ECU.

1. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Disconnect wiring from coolant temperature sensor. Plug jumper end of test resistor into harness connector of temperature sensor. Unplug oxygen sensor. Turn ignition on.
2. Differential pressure regulator current should be 9-11 mA. Ground Green wire of oxygen sensor. Differential pressure regulator current should increase to 19-22 mA. If not, check wiring from terminal No. 8 of ECU connector to oxygen sensor. If wiring is correct, replace ECU.

1. Before testing oxygen sensor, check the following conditions: engine oil temperature at 176°F (80°C) minimum, radiator fan must cycle at least once, pressure gauges NOT connected, exhaust system free of leaks, oxygen sensor control working properly, all electrical units turned off (radiator fan and A/C must be off during test), and engine speed at 3000 RPM for 2 minutes.
2. Connect test harness between differential pressure regulator and vehicle harness. Connect multimeter to test harness. Run engine at idle. After 2 minutes running time, oxygen sensor is heated up enough to work.
3. Current reading should fluctuate at idle. If not, check current reading at 3000 RPM. If reading fluctuates, oxygen sensor is good. If reading does not fluctuate at 3000 RPM, replace oxygen sensor.

Duty Cycle Valve

1. To measure oxygen duty, connect Tester (VW 1367) with Adapter (US 1112) on duty cycle connector. DO NOT connect Inductive Pickup (VW 1367). Press "%" (percentage) button.
2. Remove auxiliary air regulator connector and connect it to connector of Remote Control (US 4480/3). Connect "alligator clip" to battery positive terminal "+". Operate switch on Remote Control (US 4480/3). Duty cycle valve must audibly click.
3. If duty cycle valve clicks, test is completed. If duty cycle valve does not click, go to step 4).
4. Remove connector from duty cycle valve. Check prongs of connector and duty cycle valve for correct positioning (must not be damaged or pushed in). Measure voltage supply using Multimeter (US 1119). NOTE: Preset multimeter to "20VDC" range prior to making test connection.
5. Operate Remote Control (US 4480/3). Nominal value should be about 12 volts. If nominal value is not within specifications, go to step 6). If nominal is okay, test is completed.
6. Check for open circuit to duty cycle valve, power supply relay or control unit. If not okay, repair or replace components as necessary. If circuits are okay, replace control unit.

1. To test boost valve No. I, engine oil temperature must be at 176°F (80°C) minimum. If equipped, A/C system must be off. Run engine at idle speed. Turn on all electrical units except A/C system. Turn in idle speed adjusting screw to lower idle. At 750 RPM, boost valve No. I should open and idle speed will increase.
2. Pinch shut outlet air hose after "T" connector. Engine speed should drop. Leaving air hose pinched shut, raise engine idle speed to 870-930 RPM. Open air hose. Idle speed should increase. When 1050 RPM is reached, boost valve No. I should close and engine speed should drop to 870-930 RPM.
3. To check boost valve No. II (A/C equipped only), make sure A/C is off. Run engine at idle speed and pinch outlet air hose shut. Engine speed should not change. When A/C is switched on with air hose pinched shut, idle speed should drop.

Idle Speed Stabilization System

1. Engine oil temperature must be at 176°F (80°C) minimum. Ignition timing must be correct and A/C must be off. Connect Dwell Meter (VW 1367) using Adapter Cable (US 1112). Set "%" button on dwell meter and check duty cycle.
2. Reading should be 26-30% with oxygen sensor connected. If not, adjust duty cycle. See TUNE-UP article in the TUNE-UP section.
3. If reading shows 33% or 40%, make sure A/C is switched off. If A/C is off, check idle throttle switch function. Check for open circuit between idle switch and ECU connector.
4. If reading is fluctuating between 20-25%, check for open circuit in RPM signal from ignition ECU. If reading is steady 25%, idle speed is incorrect. Check for air leaks in throttle body. If no leaks are found, check for open circuit between ECU and idle stabilizer control valve. If circuit is correct, replace control valve.
5. Turn A/C on. Idle speed should increase by 100 RPM. If not, check for open circuit between A/C switch on dash and terminals No. 6 and 16 on ECU connector. Check for RPM increase of 100 RPM when A/C compressor cycles off.
6. If idle speed goes over 1000 RPM when A/C compressor switches off, check compressor signal wire to ECU. Wire should go to ECU connector terminal No. 19 but has been interchanged with terminal No. 16. Check wiring diagram and correct.

Throttle Valve Switch

See ADJUSTMENTS for checking and adjusting procedure for idle and full throttle valve switches.

Note. CIS-E fuel injection maintains constant fuel pressure throughout system. Relieve pressure before opening system. DO NOT allow fuel to leak on engine or electrical parts. DO NOT allow any open flame near fuel system being serviced.

Removal

1. Disconnect battery and remove air cleaner. Disconnect all fuel and injector lines from fuel distributor. Plug fuel feed and return lines. Catch any fuel spillage with rag.
2. Disconnect wiring from differential pressure regulator. Remove 3 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. DO NOT damage "O" ring as 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. Adjust engine idle.

1. 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.
2. Disconnect 2 contour hoses from idle speed air distributor. Unscrew injector lines while applying counterhold to injector. Remove fastening bridges. Pull out fuel injectors.

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 vehicles with 2-piece inserts, replace insert sealing washer (against head) and use sealing compound on upper insert threaded portion.

THROTTLE VALVE HOUSING (TVH)

Note. Only adjustment procedures are available for throttle body. See ADJUSTMENTS for procedures.

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.

Note. Only adjustment procedures are available for airflow sensor plate. See ADJUSTMENTS for procedures.

Remove air cleaner and unscrew stop bracket. Heat fastening bolt for airflow sensor plate with hot air blower to loosen locking compound. Unscrew bolt carefully as there is risk of tearing threads. Use 6 mm tap to clean out threads for airflow sensor plate fastening bolt.

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

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 properly. See ADJUSTMENTS.

CIS-E Wiring Diagram (4000S & 4000S Quattro - 4 & 5-Cylinder). Scheme 10

CIS-E Wiring Diagram (5000S). Scheme 11

CIS-E Wiring Diagram (5000CS - Turbo & Quattro). Scheme 12

See also:
• ADJUSTMENTS