1994 Olds 88 Royale, 3800 V6, OBD-I (OBD-II connector), auto
intermittent MIL lamp. Clears on next start. History code is always P1406, EGR
pintle position error. PCM to EGR signal lines continuity check, good.
key on, running at idle, normal operating temp, tranny in park:
EGR control line RA16 (also at EGR harness pin A), B+, good
EGR +5 reference line WC10 (also at EGR harness pin D), 5.05V, good
EGR pintle position BF12 (also at EGR harness pin C), .72V, good
road test, monitor DVOM voltage at EGR pintle position line at PCM (BF12):
on accelleration, BF12 goes to 3-5V
speed at 25-30mph, foot off accelerator, BF12 goes to .72
come to stop, BF12 is .72
feather foot the accel, BF12 drops to .35-.55V, before jumping to up to normal
voltage, seconds later MIL sets.
what could cause the EGR pintle position signal to drop below .72v? Could
another sensor like the TPS upset the reference voltage to the EGR valve?
Please advice. I am going out of my ever loving mind!
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