philiow313 Posted September 18, 2004 Share Posted September 18, 2004 ok so my exhaust had a really bad problem with popping/backfiring... i had a feeling my O2 sensor was bad, so i disconnected it and grounded the harness side to the intake manifold, and the popping is virtually gone, but i noticed my gas mileage is HORRIBLE now. bout 50 miles on a 1/4 tank. is it a good idea to leave it grounded, and just deal with the low mileage? or should i connect it back up and just live with the popping until i get the new sensor? also, with it grounded, im running really lean right? or am i backwards, and really running rich now? im not used to old nissan electronics, i dont know if its the same as cars today. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 18, 2004 Share Posted September 18, 2004 backwards, rich... when signal from O2 sensor goes out of spec for more than 3 seeconds, ECU goes "full rich" and stays there until signal is rectified. You have false air or vacuum leaks in your system. Get out the spray bottle and find them. Quote Link to comment Share on other sites More sharing options...
philiow313 Posted September 18, 2004 Author Share Posted September 18, 2004 i just recently replaced all but 1 or 2 vacuum lines which looked in ok condition, but were mostly just gonna be a pain to get to . so should i reconnect the sensor for the time being? i replaced the clogged cat a few weeks back and was advised to replace the sensor, but at $110 bucks from nissan i couldnt afford it. as far as the vacuum leaks go, the "thermal vacuum valve" that sits about dead center on the intake manifold always seems to be sucking air in from the backside... would this be a problem, and how do i fix it? Quote Link to comment Share on other sites More sharing options...
Clifton Posted September 18, 2004 Share Posted September 18, 2004 Checker has them for $38. Quote Link to comment Share on other sites More sharing options...
dot Posted September 19, 2004 Share Posted September 19, 2004 I was having problems with mine and found a test on Google. "All you need to test an oxygen sensor is a propane torch, vice grips, and a 10 meg ohm input impedance meter capable of measuring low voltage (1 volt and less). If you are going to buy one, ask for a high impedance (10,000 ohms) digital type. Connect the voltmeter. Then heat the tip of the sensor, holding the tip completely in the flame. Move the torch flame over the sensor tip. The tip should be hot enough to turn cherry red, and the flame must enter the opening into the sensor tip. Meanwhile, keep an eye on your meter. If you get a reading above 600 millivolts, and the reading quickly changes with the movement of the flame over the tip, the sensor is OK. Otherwise, replace the sensor." After doing the test my O2 sensor worked great. Probably because it burnt all the crap off of it. Then it died a week later and failed the test. It will give you some thing to do until you save for a new one. Quote Link to comment Share on other sites More sharing options...
philiow313 Posted September 19, 2004 Author Share Posted September 19, 2004 well im a genious and never checked the local parts stores picked one up with my student discount for $26 bucks. installed it, and there is still less popping then there was before all this, but more than when i had the harness side of teh wire grounded out. what about the themal vacuum valve? what can i do about that, it seems like that would be un-AFM metered air entering the system...? Quote Link to comment Share on other sites More sharing options...
philiow313 Posted September 24, 2004 Author Share Posted September 24, 2004 ok so there have been no replies =/ if i cover the opening on the TVV, the engine runs like crap. ok, so maybe not it. anyone care to point me in another direction to fix the popping? Quote Link to comment Share on other sites More sharing options...
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