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Showing results for tags 'Air/Fuel'.
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Fairtax4me posted a topic in 1990 to Present Legacy, Impreza, Outback, Forester, Baja, WRX&WrxSTI, SVXAdditional info required: A while ago (like a year or more) there were some threads floating around about O2 sensor voltage readings in the 3+ volt range on diagnostic scanners. I don't recall there being a clear answer as to the reason at the time. I have had some O2 sensor issues recently so I went digging for info and basically found that the reason for the trouble was that I bought the wrong type of sensor. I bought an O2 sensor, when what I needed was an Air/Fuel Ratio sensor. The problem was on a Toyota, but the same principles of how the sensors differ apply to every brand of vehicle. The link below comes from a website we use in school, and has tons more info about various sensors and their functions, as well as dozens of other tech articles that can be useful during diagnosis of a problem. What my issue boiled down to is the ECU was getting a reading of incredibly lean mixture from the O2 sensor. Because on an O2 sensor rich = high voltage and lean = low voltage. but wih an A/FR sensor its the opposite, rich = low and lean =high. The ECU would add more fuel and get a rich voltage back rom the sensor,except the ECU is programmed to read high voltage as lean, even though the sensor was responding as it should. And so the cycle repeats itself until the ECU can no longer adjust, which in this case pegged the Long Term Fuel Trim at 44.5%. But back to the point, if you get oxygen sensor voltage reading in the 3V range on a scanner, its because you have an Air/Fuel Ratio sensor, which gets supplied a reference voltage of 3.3V from the ECU. The sensor then bumps up (if lean) or bumps down (if rich) the return voltage signal back to the ECU. Some ECUs convert scanner output to a normal O2 sensor output voltage to avoid confusion, but not all. Be sure of what you have before purchasing a replacement sensor. http://www.autoshop101.com/forms/h37.pdf
Hi Guys, the last two days in a row now I've had a really hard time starting my '87 GL. this morning it took me about 30 minutes of trying, and I finally got it after about 30 seconds with the starter going, and gently feathering the gas pedal juuuust right. It almost started and then stalled a few times before I finally got it. This is something that has happened VERY infrequently while I've owned this car, like four other times in the last 8 months, and now two days in a row. Right now I'm traveling around rural Alaska and so having the car start consistently and correctly is an absolute must. While I was trying to get it started this morning I took off the kick panel to look at the ECU and see if it was flashing a code that might help me diagnose what's going on here. It flashed a very short blip 6 times, then a pause, and 6 more blips, all very short. By my understanding this means the code is number 6, but my FSM doesn't have a code 6 listed. Anyone know what that might be? After looking through the forums for similar threads I think my culprit is probably the CTS. Or maybe the fuel injector? There's a very strong gas smell as I'm trying to start it up that makes me feel like it's getting flooded. Though once I get it up and running it runs perfectly fine, and I put a can of seafoam in the gas tank just a few tanks ago so I'm not sure if the injector would be stuck I'm debating putting in new spark plugs and replacing my fuel filter as well while I'm at it, any thoughts or suggestions on a reliable startup are welcome and appreciated.