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Re: Ari----check this and on Fri. Please Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 22 Feb 2005 08:12:36
In Reply to: Ari----check this and on Fri. Please, Rmc, Tue, 22 Feb 2005 07:50:27 Members do not see ads below this line. - Help Keep This Site Online - Signup |
That does sound like strange operation. 0.5 is perfect stochiometric ratio, which is very hard to achieve by accident. And 0.9 volts is rich running.
Try a couple of tricks - Start the engine, and let it idle about 2 minutes. With the O2 sensor reading 0.5 volts, first pop the vacuum line off the fuel pressure regulator, and plug the end going to the throttle body. The voltage should pop instantly to 0.9 - rich. Reconnect the hose. Now, pop any other vacuum line from the throttle body - the one going to the turbo boost gauge is nice. The O2 sensor voltage should snap to 0.2 or so ,maybe lower.
If both those things don't happen, then I'm guessing that the O2 sensor is bad. The other possibility is that the O2 sensor heater isn't working - either the voltage for the sensor isn't present, or it's just bad in the sensor. There are two white wires going to the sensor - you should have 12 volts or so on one, and ground on the other. Not 0 volts, ground. That's when the car is first started. With one of those wires disconnected from the cable harness, measure the resistance between the two white wires on the sensor - it should be a few ohms. Not sure of the exact value, but probably something under 10 ohms. If it's open, then the heater circuit in the sensor is shot.
About the only things I can think of are a cold sensor or a slow sensor. O2 sensors don't start running until they hit around 200 degrees C - that's what the heater is for. If the heater isn't working, the output will read funny until the exhaust gas warms it up, which is much more than 2 minutes. That could be due to a bad circuit in the sensor, or it's not getting power or ground. The other possibility is a slow sensor - as they age, they respond slower and slower. Minutes is pretty darn slow - I think more on a second or two, which is too slow to control the engine.
I'd check the heater source voltage and ground before changing out the old sensor. There is an in-line fuse for the O2 sensor, but I'll be damned if I can remember where it is. Unlikely that it's blown, but it's always good to check.
posted by 192.249....
, Tue, 22 Feb 2005 08:12:36 <-- Viewing This Message
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