Posted to Technical Discussion Forum on 1/23/2013
31 Replies
Hi everyone!
I've worked on GMs for 28 years, and they usually cooperate
with me, but today, I have two in a row that are causing me
grief!
Could I bother you people for a couple of minutes to help me
brainstorm? I need a fresh perspective on these, and maybe
some of you have had similar problems that you solved.
1) 2001 Impala 3.8L VIN K. Sets a P1404 for closed EGR
performance. Customer brought it in with a new linear EGR
valve installed, and the same code that it had before the
'repair'. On my Genisys, EGR minimum learned voltage is
0.24, and actual minimum voltage is 0.73. The valve passes
the bi-directional functional test, but I can't figure out
how to trigger the PCM to 'relearn' the new minimum. I have
tried: 10-minute batt disconnect, DTC clear, crankshaft
relearn, EGR disconnect and reconnect with KOEO, and a
couple of others, in no particular order, but I can't get
rid of that dang 0.24. Do I need a TECH 2?
2) 1987 Chevy R30 7.4L VIN N. Won't go into closed loop,
even after thermostat install. O2 reads 0.00 at idle, and
0.98 at 2500 rpm. Coolant 190F. BLM and Integrator both
stuck @ 128, always. No codes. I tried repeatedly goosing
the throttle to generate some cross-counts, but no dice ...
always OPEN loop. Are you aware of any PIDs other than the
obvious that could prevent CLOSED loop, or am I barking up
the wrong tree altogether?
Thank you, kind people,
Michael Barry Technician Quick Stop Smog & More Sacramento, California, USA
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