cal_look_zero Posted December 23, 2011 Share Posted December 23, 2011 Well damn, I thought I could get away with the Google providing useful answers, but no such luck. Still working out the kinks on the Legacy. Fuel mileage still sucks, but I'm whittling down the possibilities. One thing I'm fighting with is that the car will occasionally "stumble" at highway speeds. 70 or so mph, cruise control on, the car will buck like it all of a sudden has no fuel. Fuel filter is newish, and the pump works fine on heavy acceleration above and beyond 80mph (closed course) I have no engine codes, but I'm leaning towards a fouled o2 sensor based on the crap gas mileage and this inconsistent stumble. Tomorrow I'd like to pull the o2 and give it a once over. I "fixed" the obscenely expensive o2 sensors in my Mitsubishi with a scotch brite and contact cleaner. I'd like to think about other options; both for what may cause the stumble, and other ways to bypass the o2. I would prefer to inline a resistor or trick it some other way, because frankly my dear, I don't give a damn about o2 sensors. Fuel filter is newish, this stumble has been present ever since I got the car, recently seafoamed the intake and gas tank (didn't seem to help or hurt anything), plugs and wires are new, new knock sensor, and bob's your uncle. Quote Link to comment Share on other sites More sharing options...
lmdew Posted December 23, 2011 Share Posted December 23, 2011 The front O2 sensor is necessary for the ECU to properly correct the fuel ratio. If you have a good scanner, you can watch the O2 sensor response and get an idea of the rich or lean condition of the car. The random bucking could be the cam or crank sensor going out, but that should throw a code, so should a mis-fire. Is the CEL working? Have you tried pulling the codes even if the light is not on? Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted December 23, 2011 Author Share Posted December 23, 2011 CEL definitely does work. I had briefly considered the cam sensor, fortunately I have a known good one laying around. So I cleaned the o2 sensor, put in a new CTS (hoping that helps mpgs) and installed the known good cam sensor. Going to run it in d check today and see if anything comes up. Don't want to replace the oxygen sensor, but that's the next step. I say I'm not too concerned about it because I'm going to run a catless setup on the UEL when I get the money together, so fouling cats won't be an issue. Quote Link to comment Share on other sites More sharing options...
bstone Posted December 23, 2011 Share Posted December 23, 2011 CEL definitely does work. I had briefly considered the cam sensor, fortunately I have a known good one laying around. So I cleaned the o2 sensor, put in a new CTS (hoping that helps mpgs) and installed the known good cam sensor. Going to run it in d check today and see if anything comes up. Don't want to replace the oxygen sensor, but that's the next step. I say I'm not too concerned about it because I'm going to run a catless setup on the UEL when I get the money together, so fouling cats won't be an issue. Scan it for codes anyways. There might be a pending one. Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted December 23, 2011 Author Share Posted December 23, 2011 No codes; stored or during d check. But the stumble has been solved; at least the source. I noticed it right off today as I was about 5 miles into my drive to work. Decided to test a theory I had and took it off cruise; no more stumble. It's something related to the cruise system, but at this point, I can live with it. Quote Link to comment Share on other sites More sharing options...
cal_look_zero Posted December 24, 2011 Author Share Posted December 24, 2011 (edited) This keeps getting better and better... :horse::horse: I popped a very brief CEL tonight. Stopped and hooked up the greens and drove. Went from the "all good" blip, to a steady flashing CEL. So I pulled over, disconnected the green, connected the black, and got this laundry list: 11 Crank angle sensor or circuit 22 Knock sensor or circuit 35 Canister purge solenoid or circuit 41 Air/fuel adaptive control 42 Idle switch or circuit 49 Airflow sensor 51 Neutral switch (manual transmission)/inhibitor switch (automatic transmission) So I wrote em all down, then connected the green and black, fired up the engine and got the all clear blip of the CEL. Turned off the car, disconnected the black and hooked up the greens. put the car into d check, and drove home with the all clear blip. Get home, disconnect the green, hook up the black, turn the key to on, and guess what... 11 Crank angle sensor or circuit 22 Knock sensor or circuit 35 Canister purge solenoid or circuit 41 Air/fuel adaptive control 42 Idle switch or circuit 49 Airflow sensor 51 Neutral switch (manual transmission)/inhibitor switch (automatic transmission) Same codes as before. No CEL on under normal driving, "cleared" the codes, and they STILL come up under the stored memory. And I cooked through nearly 1/4 of a tank in 35 miles. Correct me if I'm wrong, but the car won't run if there's an issue with the crank angle sensor; right? Which would then mean that my ECU is storing ghost faults and adjusting everything as if they were real codes which results in CRAP fuel economy? EDIT: I'm a stupid monkey. Followed this http://www.scoobypedia.co.uk/index.php/Knowledge/ECUReset and everything cleared and runs 100x better now. Edited December 24, 2011 by cal_look_zero Quote Link to comment Share on other sites More sharing options...
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