EGR Function Testing Chevrolet Sprint I

INTRODUCTION

Note. Introduction information not applicable.

WITHOUT MODULATOR OR WITH BACKPRESSURE TRANSDUCER

1. Check vacuum lines for correct routing. Disconnect vacuum hose at EGR valve and plug hose end. Connect vacuum pump to EGR valve. Start engine. Apply 6-10 in. Hg to EGR valve and hold.
2. Engine speed should drop at least 100 RPM or stall. Vacuum should not drop more than 1 in. Hg in 30 seconds. Reconnect EGR vacuum hose.

WITH MODULATOR

1. Check vacuum lines for correct routing. Disconnect vacuum hose at EGR valve and plug hose end. Connect vacuum pump to EGR valve. Start engine. Apply 4.7 in. Hg to valve and hold.
2. Engine speed should drop at least 100 RPM or stall. Vacuum should not drop more than 1 in. Hg in 30 seconds. Reconnect EGR vacuum hose.

EGR BACKPRESSURE TRANSDUCER

Remove hose from exhaust fitting at backpressure transducer. Blow into fitting and ensure transducer holds pressure.

MODULATOR VALVE

1. Disconnect all vacuum and exhaust pipe hoses from modulator valve. Cap fittings going to each EGR control solenoid. Blow into bottom fitting from exhaust pipe end.
2. Apply 7 in. Hg to fitting No. 3 (from ported vacuum source). Vacuum should hold until pressure at bottom fitting is released. If further testing is required, see SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE section.