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Blinking check engine light???

Discussion in '80-Series Tech' started by Snorkel 1, Mar 1, 2007.

  1. Snorkel 1

    Snorkel 1

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    OK, this is worrying me a little. When I turn the ignition to "on" my engine light blinks 1-2 times a second. When I start the engine the light goes out. It starts and runs fine. It had sat unused for about 6 weeks and I had to jump start it the first time. Any thoughts?

    I have been sorting out a problem with my rear O2 sensor throwing a code recently (?? P0171 ??). At least I think it is my O2 sensor even though I have replaced it about 5-10k ago. I have not had much time to look into this lately.

    Thanks.
     
  2. dfmorse

    dfmorse

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    How old is Battery? What year '80? Is the charging system stock?

    ...
     
  3. Lugboot

    Lugboot

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    P0171 is System too Lean or Fuel Trim too Lean (Bank 1). The O2 sensor may have detected it but it may not be the O2 sensor that is faulty.

    Disclaimer: Yes, I pulled this from an OBDII DTC reference but it might help you.


    Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.
    Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
    You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.
    A code P0171 may mean that one or more of the following has happened:
    • The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
    • There could be a vacuum leak downstream of the MAF sensor.
    Possible solutions include:
    • In the vast majority of cases, simply cleaning the MAF sensor does the trick. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
    • Inspect all vacuum and PCV hoses, replace if necessary
    • Check for a dirty fuel filter and proper fuel pressure
     
  4. Snorkel 1

    Snorkel 1

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    The batteries are two years old or less and are red top Optimas. The charging system is basically Slee's dual batt setup without the disconnect switch in the cab. It has been working fine since it was installed two years ago so I think it should be OK. I did leave the key in the ignition (in the "off" position) accidentally for about 2-3 weeks of the 6 it was parked which I think is why it drained the batts :confused: . This has happed before but not to the point that it would not start.

    I will try these fixes and post the results. I have never checked the fuel filter in these. How do I check for a dirty fuel filter? I may just replace it anyway. It may have picked up some dirt from the aux tank install.

    Any thoughts on why the CEL would be blinking though? I don't remember seeing this talked about anywhere.

    Thanks for the input. I knew someone here would be able to help sort this out. :cheers:
     
  5. IdahoDoug

    IdahoDoug

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    Um, guess it's top secret, but I'll ask again since DF didn't get an answer:

    What year/engine are we talking about here???

    DougM
     
  6. landtank

    landtank SILVER Star

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    Lets work on the assumption we have a 95+ truck here.

    P0171 is the front sensor not the rear O2 sensor.

    The first thing I'd check is for a crack in the exhaust where the two down pipes merge from the exhaust manifold. These tend to crack and allow air to enter the system giving a lean error.
     
  7. Snorkel 1

    Snorkel 1

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    I had a signature on here but it disappeared. Sorry about that. here is the info:

    1997, 4.5L, supercharged, dual batts using Slee's setup, Toyota O2 sensors

    Let me know if anything else is needed. Thanks.
     
  8. Snorkel 1

    Snorkel 1

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    Would a crack be visible to the naked eye or probably not? If not how could I tell? There is no exhaust smell in the cab though.

    There was some rust on the surface the O2 sensors are mounted to. I cleaned them as best I could and I was confident they would mount clean but how would I know if there was a leak there. Put some soapy water on it while it is running before the exhaust gets too hot?