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Solid CEL, but car still starts. Need some advice.

Discussion in 'ECU's, Electronics, and Tuning' started by wikedeye, Feb 6, 2012.

  1. wikedeye

    wikedeye Well-Known Member

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    Today I went out to my car to go to the store and I got a cel. I jumped the harness and got a solid cel. I have had this problem before about a year and a half ago, but when it happened before I was not able to start the car. I had to replace the ecu when it happened the first time. From what I can gather from searching the problem, the car would not start if the ecu was bad. I may be wrong about that. I have turned the ignition on and pulled the map sensor and tps sensor, one at a time, to see if that had any effect on the cel. It did not. I also notice a slight hum coming from somewhere in the engine bay. It sound like some kind of an electrical hum. It comes on when the ignition is turned on and it stays on after the fuel pump has primed. I can not locate the hum. I have tried using various types of tubes and other magnification methods to track down the sound, but I have been unsuccessful. Also the fuel pump does prime. One thing that I did notice is that the timing belt seems a little loose. I don't know if this would cause a cel light come on and stay on, but I will fix the tension tomorrow and see what happens. I looked through the helms for some help, but I don't have the ecu adapter for testing. I also do not know anyone locally with another ecu to try. If anyone has any advice it would be greatly appreciated
     
    Last edited: Feb 6, 2012
  2. wikedeye

    wikedeye Well-Known Member

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    Any suggestions as to what causes a solid cel? I could really use some help narrowing down the causes.
     
  3. Fernpatch

    Fernpatch Member

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    Have you checked all your relays for the humming sound? also does your car still have all of the evap system intact? I have seen the purge solenoids start humming a weird tune before. Usually caused by a bad ground for the ecu or a failed ecu.
     
  4. wikedeye

    wikedeye Well-Known Member

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    No on the evap system.

    Do you mean the relays in the under hood fuse box? I am pretty sure that it is coming from the middle of the fire wall, or at least that is as far as I have been able to narrow it down. I will check the relays in the fuse box to be sure.
     
  5. TurboMirage

    TurboMirage YEEAAAHHH VIP

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    was your climate fan on? in the dash?
     
  6. wikedeye

    wikedeye Well-Known Member

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    No the ac and heat were off.
     
  7. wikedeye

    wikedeye Well-Known Member

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    I made a paper cone so I could hear better and now I am pretty sure that the hum is coming from the fuel rail area. I still can't find the source, bug I am closer.
     
  8. wikedeye

    wikedeye Well-Known Member

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    Well it seems to be an intermittent problem. I started doing some troubeshooting. I checked the injectors and they were working. I checked the timing and it was extremely rich. I pulled up the helms and started testing the ecu. I went through the flowchart and ended up with the conclusion that the ecu was bad. So I disconnected it and pulled the cover to do a visual inspection. Everything looked good, so I pulled the chip out of the zif to inspect it. It looked good as well. I put it all back together and hooked it back up and now there is no code and the car runs like it did before. I dont think that I really did anything to fix the problem, but the problem is gone for the time being.

    One thing that I noticed while testing the ecu is that the flowchart indicated that there was a short in the service connector. I tested for continuity between the d4 and the connector and the d22 and the connector and they both tested fine, but I still get 5v when I test the d4 and d22 together with the service connector jumped. According to the helms I should not get any volts with that scenario. Is it possible to show continuity, but still have a short? The reading was flickering between 0 and 1 on both wires.
     
  9. eg4drgsr

    eg4drgsr New Member

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    Humming is coming from IACV, I have the same problem. Trying to figure out whats causing it to hum, I have no CEL, but did and got rid of them all.. very confused.. sorry if this thread is kinda old, just found it interesting..
     
  10. wikedeye

    wikedeye Well-Known Member

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    Thanks for the tip. I figured out the cel and now the humming is gone.
     
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