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mark houghton mark houghton is offline
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Join Date: Jul 2008
Location: Central Washington State
Posts: 3,861
By unplugging a known working O2 sensor, the computer (and frequency valve) would respond by reducing fuel to the engine (because it would read as zero oxygen being present and too rich). Sounds to me like your Lambda circuits are working correctly. If not working correctly, then by unplugging the O2 you shouldn't see any change at all and the idle would still be crappy. If the sensor were bad, then even with it plugged in the car would be running in 'open loop' as though it were unplugged and unless you had tuned it to run open loop, it would run crappy plugged or unplugged.

How's your rear fuel pump relay? Perhaps you've lost the voltage to the heating element in the WUR and it's reverting to cold start control pressures and thus rich. You unplug a perfectly good O2 sensor, the Lambda computer says (****, I'm not smelling any air in this exhaust, I must be rich, I better lean her out).

NOTE: the O2 sensor produces millivolts in response to the oxygen content. Higher voltage = higher AFR (lean reading). Unplug it = zero voltage = lambda computer seeing false rich condition and adjusting to lean her out.
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.

Last edited by mark houghton; 01-23-2013 at 01:35 PM..
Old 01-23-2013, 01:31 PM
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