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It's not easy Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 23 Aug 2001 11:44:21
In Reply to: oxygen sensor, dein, Tue, 21 Aug 2001 15:38:55 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The O2 sensor is part of a closed loop system, so a 'bad' reading from the O2 sensor can actually be due to a different problem.
But try this - at idle, connect a digital voltmeter between the signal side of the O2 sensor (black wire, usually) and ground, and measure volts. The O2 sensor must be still connected. Ideally, the signal will be bouncing between about 0.2 and 0.9 volts. Pull off a vacuum hose - make a vacuum leak - the voltage should drop down to the 0.2 volt range - a lean mixture. Reconnect the hose, then pull off the vacuum line to the fuel pressure regulator and plug it - the voltage should go up to about 0.9 volts - a rich mixture.
OK - what if the voltage is just stuck around 0.2 or 0.9 volts? It could be a bad O2 sensor, or you could have a lean or rich mixture, and it's telling the truth. Pull some spark plugs. If the spark plugs look lean (whiteish tip) but the O2 sensor says rich (0.9), then assume the O2 sensor is lying and bad. Same if the plugs look black and the O2 sensor says lean (0.2 volts). But if the plugs and O2 sensor agree - white plugs and 0.2 volts, or black and 0.9, then look elsewhere.
Lean running can be caused by a vacuum leak or a bad AMM. Rich running can be a bad AMM or fuel pressure regulator. Usually hesistation is an AMM, and usually you're running a bit lean.
Tell us more about the sound you relate to a plug/DI. When does it happen? Is it related to engine speed? What does it sound like?
posted by 140.157....
, Thu, 23 Aug 2001 11:44:21 <-- Viewing This Message
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