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Thread: CEL light but no codes...?

  1. #1
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    Default CEL light but no codes...?

    'check engine' came on today.

    I've done the stomp test before on this car and it gave me codes, but now when i do it it flashes off for half a second then goes back on and just stays on.

    Suspected bad fuel pressure regulator, I've been getting lousy mileage lately - there is a new one on the way, but wouldn't it at least give me a code? Otherwise I don't notice anything and it idles fine. Hope it's not the cat... Ideas?

  2. #2
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    Default When my cat went bad this past year.......

    Quote Originally Posted by tim eh? View Post
    'check engine' came on today.

    I've done the stomp test before on this car and it gave me codes, but now when i do it it flashes off for half a second then goes back on and just stays on.

    Suspected bad fuel pressure regulator, I've been getting lousy mileage lately - there is a new one on the way, but wouldn't it at least give me a code? Otherwise I don't notice anything and it idles fine. Hope it's not the cat... Ideas?

    I at least got a code for the MAF. Check your voltage. Do you have a OBC to do this easily. Check you battery as well.

    JD

  3. #3
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    Quote Originally Posted by JD525IA View Post
    I at least got a code for the MAF. Check your voltage. Do you have a OBC to do this easily. Check you battery as well.

    JD
    I keep a pretty good eye on my new battery with the obc, almost daily... I will check but I'm 99% sure battery is good and that I run on 13.5+V. Thanks for the suggestion. I will check fuses then if it could be electrical, but all the codes that are listed here seem to have more to do with the ignition system and various sensors to the engine.... (?)

  4. #4
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    Default Some sensors like air flow and O2 (lambda) do show.....

    Quote Originally Posted by tim eh? View Post
    I keep a pretty good eye on my new battery with the obc, almost daily... I will check but I'm 99% sure battery is good and that I run on 13.5+V. Thanks for the suggestion. I will check fuses then if it could be electrical, but all the codes that are listed here seem to have more to do with the ignition system and various sensors to the engine.... (?)

    YEP - That was the code I got when my cat was going bad - 1215 - AFM/MAF.

    Made me say MF out loud.

  5. #5
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    ok so I just changed the plugs... cel gone (off).

    They are pretty filthy for 6 months I think. I am not a good plug reader, maybe there is something obvious to someone, maybe that is normal?

    I'm hoping it looks like lousy spark (I recently replaced the ignition coil, cap and rotor 1 year old, wires ? yrs) or low fuel pressure (changing FPR next week probably, fuel pump is good). Anyway, maybe the bad mileage is from dirty plugs too. Good excuse for a long, motorized egg hunt this weekend...
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  6. #6
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    Quote Originally Posted by tim eh? View Post
    maybe the bad mileage is from dirty plugs too. ...
    Dirty plugs and bad mileage are both symptoms. The plugs do look a bit sooty which means you are getting more fuel in the engine than it needs. Full set of trouble codes is here: http://www.e38.org/e32/bmw%20code%20defaut.pdf
    If you cant read the codes with the stomp test I'd suggest having them read with an interface or similar. The ECU cant 'know' you have changed the plugs or the FPR. So I think that CEL is going to come back again

  7. #7
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    Quote Originally Posted by whiskychaser View Post
    Dirty plugs and bad mileage are both symptoms. The plugs do look a bit sooty which means you are getting more fuel in the engine than it needs. Full set of trouble codes is here: http://www.e38.org/e32/bmw%20code%20defaut.pdf
    If you cant read the codes with the stomp test I'd suggest having them read with an interface or similar. The ECU cant 'know' you have changed the plugs or the FPR. So I think that CEL is going to come back again
    thanks wc... yeah I wasn't expecting the cel to go off when I changed the plugs but it did wtf. I was going to change them anyway and thought the old ones might have a clue. i should try to get a 1444 silly me i didn't think.

    So... too much fuel.... that can't mean weak spark also? If it was weak spark that would explain it, as the ignition coil was bad for most of the time these plugs were in there.

  8. #8
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    Quote Originally Posted by tim eh? View Post
    So... too much fuel.... that can't mean weak spark also? If it was weak spark that would explain it, as the ignition coil was bad for most of the time these plugs were in there.
    The electrodes look very 'white'. I'd expect them to look more yellow - like the tip of the one on the left. This is going to sound a bit silly, but it looks to me like they are not running hot enough. But if you had a weak spark I suppose that tallies. I'd want to know what the CEL meant. I'd run it in the dark to see if I could see any arcs that would drop the HT voltage and check the HT leads are in spec.

  9. #9
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    Quote Originally Posted by whiskychaser View Post
    The electrodes look very 'white'. I'd expect them to look more yellow - like the tip of the one on the left. This is going to sound a bit silly, but it looks to me like they are not running hot enough. But if you had a weak spark I suppose that tallies. I'd want to know what the CEL meant. I'd run it in the dark to see if I could see any arcs that would drop the HT voltage and check the HT leads are in spec.
    sorry... HT=?

    Yes I suppose it would be smart to check the wires (or dumb not to). I know for sure the coil was bad for a while.

    Will check resistance - silly question how dark does it have to be to see arcing?

    *- the plugs actually look more yellow than white... flash brightens things. That seems to check out then, thanks for that wc... will see about cel maybe it is unrelated.
    Last edited by tim eh?; 04-10-2009 at 07:58 AM.

  10. #10
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    The plugs look perfectly fine for an m20, You may have had one of you new plug wires not clipped on solidly causing a random misfire that triggered the code and after changing the plugs you now have the boots pushed down all the way... any number of possibilities, if it doesn't come back on don't worry about it.






    Quote Originally Posted by tim eh? View Post
    sorry... HT=?

    Yes I suppose it would be smart to check the wires (or dumb not to). I know for sure the coil was bad for a while.

    Will check resistance - silly question how dark does it have to be to see arcing?

    *- the plugs actually look more yellow than white... flash brightens things. That seems to check out then, thanks for that wc... will see about cel maybe it is unrelated.


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