8.1l ho2s
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Teching In
Joined: Oct 2005
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8.1l ho2s I'm trying to tune a 8.1L for a friend of mine, in a '85 chevy 4x4. The problem
is I am not getting any O2 readings from the pcm, they stay at about .455v all the time. He has the 12200411 pcm with a speartech harness. We have checked the circuits between the sensors and pcm, all ok. Tried a different pcm, with same results. It has new gm o2 sensors. I used to tune TBI/TPI stuff years ago, and am not real familiar with the OBD-II systems. On the O2 sensor signal circuit, with the O2s unplugged I have 4.75 volts, and on the low reference circuit I have 5.25 volts. Is this correct? Also the GM wiring schematic he has shows the low reference circuits for all the O2s spliced together then splitting back to separate pins in the pcm, plus one going to pin 63 (just called a low reference, not designated to a certain sensor) on the same connector, but the speartech harness he has does not splice these wires together, and does not have any wire coming from pin 63. I should mention I use tunercat software for tuning, and auto enginuity and a tech 2 for scantools. Any input would be appreciated, Phil
is I am not getting any O2 readings from the pcm, they stay at about .455v all the time. He has the 12200411 pcm with a speartech harness. We have checked the circuits between the sensors and pcm, all ok. Tried a different pcm, with same results. It has new gm o2 sensors. I used to tune TBI/TPI stuff years ago, and am not real familiar with the OBD-II systems. On the O2 sensor signal circuit, with the O2s unplugged I have 4.75 volts, and on the low reference circuit I have 5.25 volts. Is this correct? Also the GM wiring schematic he has shows the low reference circuits for all the O2s spliced together then splitting back to separate pins in the pcm, plus one going to pin 63 (just called a low reference, not designated to a certain sensor) on the same connector, but the speartech harness he has does not splice these wires together, and does not have any wire coming from pin 63. I should mention I use tunercat software for tuning, and auto enginuity and a tech 2 for scantools. Any input would be appreciated, Phil
