EGR - MIL ON DTC 2411 Diagnosis

9229audi01

Group: 26

Number: 92-01

Date: 03/10/92


Subject:
Exhaust Gas Recirculation - System Testing

Model(s):
100 With 5 Cyl (NF Engines)
80/90 With 5 Cyl (NG Engines)
(California Only)

M.Y. 1990-1991

Condition

Engine warning light comes on and DTC 2411 (EGR system) is stored in fault memory. (DTC = Diagnostic Trouble Code = fault code)

Requirement

^ EGR system vacuum and electrical connections OK

^ A/C switched off

^ Engine at operating temperature (radiator fan cycles at least once)

^ All electrical consumers off


Functional check

- Switch OFF ignition

- Connect VAG 1367 engine tester, red lead to positive and black lead to ground

- Disconnect electrical connector of EGR frequency valve





- Pull rubber boot back and connect green lead of VAG 1367 engine tester to black/blue wire using 1594/12R test probe

- Reconnect electrical connector to EGR frequency valve


- Depress % button on VAG 1367 engine tester





- Using a vacuum tee - install vacuum gauge into EGR vacuum line at the EGR valve (EGR valve remains connected to the vacuum line)


Start engine and let idle:

^ Vacuum gauge must read 0 in. Hg

If NO Check vacuum hose routing or replace EGR frequency valve

Increase engine speed to 2000 RPM (use vehicle tachometer if necessary):

^ Duty cycle display on VAG 1367 must read 32% +- 10% at 2000 RPM (duty cycle threshold is 1800 RPM; it will not register below that speed)

If NO Check wiring or replace fuel injection control unit

^ Vacuum gauge must read at least 4 in. Hg





If NO Check vacuum hose routing and assure that manifold vacuum is present at EGR frequency valve or replace EGR frequency valve





- Return engine to idle
- Connect hand vacuum pump US 8026 to EGR valve vacuum port

- Apply 4 in. Hg of vacuum to EGR valve with engine idling

^ Engine must idle rough
^ EGR valve must hold vacuum

If NO
- Replace EGR valve


Dynamic System Checking (Checks performed during a road test)


- Using 1598/3 adapter harness, install VAG 1598 test box between fuel injection control module and vehicle harness

- Connect Fluke 83 multimeter with positive lead to terminal 6 and negative lead to terminal 35 of VAG 1598 test box

- Switch Fluke 83 multimeter to 20V range

- Start engine and let idle (EGR is not operating)

^ The voltage drop of the temperature sensor must be 4.6 V to 5.3 V at idle

Note
The temperature sensor is the triggering device for the dash warning light


If voltage is too low:
- resistance of the temperature sensor too low; must be 80-160 kOhms at 100~C (212~F)
- poor/loose ground connection
- EGR valve stuck open
- low voltage supplied from ECM; must be approx. 5 V (ECM = Electronic Control Module = ECU)

If voltage is too high:
- resistance of the temperature sensor too high; must be 80-160 kOhms at 100~C (212~F)
- high voltage supplied from ECM; must be approx. 5 V (ECM = Electronic Control Module = ECU)


If voltage is correct:
- Drive vehicle at a steady speed of 55 MPH and a steady RPM over 2000 (use cruise control)

^ Within 2-3 miles of driving, voltage must drop to below 1.3 volts

If NO
- Check steel tubing between EGR valve and exhaust manifold for restrictions.

- Check threaded couplers at each end of steel tubing, must have inside diameter (I.D.) of 8 - 9 mm

If steel tubing and threaded couplers are OK check temperature sensor
- switch off ignition
- remove EGR temperature sensor from EGR valve
- switch multimeter to resistance range
- connect multimeter between terminals of temperature sensor using jumpers
- place temperature sensor in boiling water and measure resistance
- multimeter must read between 80 kohms and 160 kohms





If not
- replace EGR temperature sensor

If EGR temperature sensor is OK but voltage does not drop below 1.3 volts on road test
- replace EGR valve


Important
After repairing EGR system, road test vehicle and repeat dynamic system checks. Temperature sensor voltage must drop below 1.3 volts after 2-3 miles of driving.


Labor operation

26 A2 0000; 125 TU includes system checking and road test (quality check)





Exhaust Gas Recirculation - System Testing Check Sheet - use to Record Information When Checking EGR Systems