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Home >> Buick >> 1994 >> Regal V6-231 3.8L VIN L SFI >> Repair and Diagnosis >> Powertrain Management >> Emission Control Systems >> Exhaust Gas Recirculation >> Testing and Inspection
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Exhaust Gas Recirculation: Testing and Inspection

EGR Valve Check (Chart C-7):




EGR System Circuit Diagram:






CIRCUIT DESCRIPTION
The linear Exhaust Gas Recirculation (EGR) valve is designed to accurately supply EGR to an engine independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through an orifice with a PCM-controlled pintle.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Ensures that the EGR valve is allowing EGR flow and the PCM is capable of controlling the EGR valve. The engine should run extremely rough, and may even stall at the 75% and 100% positions.
2. Ensures that circuit 435 is not shorted to ground.
3. Ensures that circuit 435 is not open and that the PCM driver is functioning properly.

DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.

Check for:
^ Poor connection or damaged harness. Inspect PCM harness connectors for backed out terminal "RA16", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.
^ Intermittent test. if connections and harness check OK, disconnect PCM black connector "A" and monitor a digital voltmeter connected between PCM terminal "A1" and ground while moving related connectors and wiring harness. if the failure is induced, the voltage reading will change.
^ Check for a restriction in EGR tube or passage. Also, ensure there is not excessive carbon buildup on EGR valve pintle and orifice.

NOTE: If the linear EGR valve shows signs of excessive heat, check the exhaust system for blockage (possibly a plugged converter.) Refer to "DIAGNOS5TIC CHARTS/CHART B-1." B Charts

If the exhaust system is restricted, repair the cause; possibly an ignition misfire or an injector which is open due to one of the following.
A. Injector stuck open
B. Grounded injector driver circuit
C. Possibly defective PCM

If this condition is found, the oil should be checked for possible fuel contamination.

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