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1999 Corolla P0171, what should I do next?

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  • #555976
    Bad_dudeBad_dude
    Participant

      Hello everyone,
      I have a 1999 Corolla VE. I just recently get the code P0171. Since this car does not have Mass Air Flow Sensor, what could it be?
      -Dirty IAVC?
      -Bad O2 sensor bank 1.

      Thanks.

    Viewing 11 replies - 31 through 41 (of 41 total)
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      Replies
    • #621458
      JohnJohn
      Participant

        What exactly have you done since your last post? Lets start from here again. banana:

        #621525
        EricTheCarGuy 1EricTheCarGuy
        Keymaster

          Yea, it’s been a while. What have you done since your last post?

          #621575
          A toyotakarlIts me
          Moderator

            If you still cannot find your issue, I recommend you take it to a shop that specializes in Asian makes that has a Toyota specialist… They can probably find the issue in less than an hour…

            Not trying to insult you, but P0171’s are not usually that hard to fix on a Corolla, and even easier on the 98 and 99 because they were non-vvt and had no MAF sensor.

            -Karl

            #643299
            Bad_dudeBad_dude
            Participant

              Sorry guys, I have not done squad. Smog is due in January. Got to find some time to fix it. I know it’s probably something easy. There’s no vacuum leak. I suspect the O2 sensor. I need to get my hands on a scanner to check the switching data on the sensor. Does the upstream goes out more often than the downstream one?
              Thanks.

              #646051
              Bad_dudeBad_dude
              Participant

                So I bought the Denso O2 sensor from Rock Auto, replaced bank 1 and the check engine light is back again. What is the next step? No exhaust nor vacuum leak that I could see. I guess only fuel injector and Fuel filter/pump in the gas tank.

                My wife took the car to a mechanic and he said for $350 he could fix the code with something call fuel pressure relay. I wonder if he means fuel pressure regulator?

                #650178
                Bad_dudeBad_dude
                Participant

                  If the air charge temperature sensor is bad, do you guys think it will give the code P0171? Air Charge Temperature Sensor

                  #886330
                  Chris ThurstensonChris Thurstenson
                  Participant

                    OK, I’m the new guy resurrecting the old topic.

                    I’ve been working on a 99 Corolla. I pulled the engine, replaced the rings, etc. The engine runs strong & doesn’t smoke. But it has the P0171 and is idling too high. I’ve replaced the PCV valve & most of the vacuum lines. I’ve tested for leaks with the carb cleaner trick. Nothing seems to indicate a vacuum leak. When I got the car it already had the catalytic converter removed and replaced with a piece of pipe. It also needs a muffler. The old one has some serious ventilation in it.

                    I have a decent Innova scan tool. It will give me live data. Part of the problem is I don’t know what the data means. I don’t have any way to know what the values should be.

                    Thank you for your input!

                    #886332
                    MikeMike
                    Participant

                      This page might give you some ideas. Hope it helps.

                      #886338
                      Billy AndrewsBilly
                      Participant

                        Sometimes you get lucky with a spray test, but to find vacuum leaks reliably, you need to smoke test.
                        What are your long term fuel trims at idle and at 2400-3000 RPM?

                        #886359
                        Chris ThurstensonChris Thurstenson
                        Participant

                          OK. Here we go. I’ve been driving it a few days. Interestingly, the fuel mileage has increased from 20mpg to 25mpg. Here’s the current codes:
                          P0420
                          P0420 (listed again for some reason)
                          P0441
                          P0446
                          So, this is different than when I started.
                          ECT 169
                          STFT B1(%) @ 2900rpm bounces all over the place between +2.3 & -3.9, at idle (1900rpm) it’s pretty steady at -11.
                          LTFT B1(%) @ 2900rpm pretty steady at -3.1, at idle (1900rpm) it stays at 0.
                          MAP (inHG) 10
                          Spark adv 16.5
                          TPS (%) 10.2
                          O2S B1 S1 (V) bounces all over from 0.090 to 0.565
                          STFT B1 S1 (%) 19.5
                          O2S B1 S2 (V) pretty solid around 0.895
                          STFT B1 S2 (%) 99.2

                          #886360
                          Billy AndrewsBilly
                          Participant

                            That is very different; you’re no longer showing a lean condition. The zero LTFT at idle definitely does not indicate a vacuum leak. Looking at what you have now, I’d say fix the evap problem and see if that fixes the performance problems. Then please install a cat.

                          Viewing 11 replies - 31 through 41 (of 41 total)
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