AFR ERRATIC. ANY THOUGHT?

Discussion in 'Fuel and Air Systems' started by swies, Mar 20, 2017.

  1. swies

    swies Wish I had more time.

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    Last fall I purchased a WideBand APSX D2. I installed it over the winter and with the motor running, it is all over the place. Flashes readings at all points if the readout. I went thru the calibration step and all went well.
    During trouble shooting (Engine off) I set the o2 sensor on the fender well. And it reads fine, as lean as possible. I put a fuel soaked towel on it and it goes full rich. It will do this all day if I want. It is the same with power/ground straight from the battery.
    Only thing I can think is the passthru I used is the same one that the tach signal wire uses? Is it possible I am getting some transient bleed? Or did I miss something else completely?
    All help is greatly appreciated.
     
  2. mario03srt

    mario03srt Hangin' with The Swamp Rat FABO Gold Member

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    Swies,

    The AFR will react to the o2 sensor "hunting" and it should swing back and forth. Especially at a cruise with a target of 14.7 Stoich. At idle it should go fronm 14.2 to 15.2 approx., at WOT is should be at a steady state to let's say 12.5 as the ecu is now in open loop and not trying to meet stoich 14.7. You should have a Bosch type on wide band sensor with a harness which plugs into a receptacle to you gage or other device then to the gage.

    FYI,

    Marion
     
  3. swies

    swies Wish I had more time.

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    I would understand if it was hunting. It is 'ALL' over the entire spectrum and will not settle at any rpm or temp. It is not just a 1.5-2 point swing. I do have the Bosch O2 sensor that came with the kit. Power and Ground were supplied direct from battery but do run through the same firewall pass through that the tach wire does from the distributor to the tach. I am thinking this may be giving me some EMR that is bleeding onto the AFR signal wire since it is reading Vdc.
     
  4. swies

    swies Wish I had more time.

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    Any help?
     
  5. mario03srt

    mario03srt Hangin' with The Swamp Rat FABO Gold Member

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    During Crusing/Idle or WOT? One should constantly range back and forth a lot. WOT should be fixed once the car starts to Eat!

    Also putting raw gas on the sensor is a no no. The sensor needs to get up to temp too, about 600 degrees off the top of my head.

    I have never experienced any elec interference issues and have always used Innovate products. One of their features in a Free Air Calibration, done in the exhaust when it is completely free of any residual fumes. This recals the sensor.

    Is this you first wide band afr gage? I have been using them for 17 years. on both NA and Boosted applications.

    Marion
     
    Last edited: Mar 21, 2017
  6. swies

    swies Wish I had more time.

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    I
    it is my first. I read on the innovate website the fuel rag test. So if it's a no no I won't do that again.
    My concern is it doesn't seem to be hunting. Just flashing all over the map. Not really up/down just hitting all points. Does not do it in key on engine off, just does it with key on engine on. If the O2 sensor needs to warm, how long should it take before it levels out some ?
    No thanks for the info. Always like to learn.
     
  7. mario03srt

    mario03srt Hangin' with The Swamp Rat FABO Gold Member

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    Well if they say that then it must be ok.
     
  8. plumkrazee70

    plumkrazee70 Well-Known Member

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    Can you post a video? I have never seen or heard of that much of a swing. Mario is right, a little swing cruising and at idle 14.7-15.2/4 is about right. Then WOT steady as a rock.

    Also where do you have your sensor? My only guess is a giant exhaust leak and even that doesn't seem like it would create a huge swing, but maybe just show leaner or richer.
     
  9. swies

    swies Wish I had more time.

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    I am at work but will try to get a video tonight when I get home and maybe get it posted in the morning.
    O2 Sensor is welded in 8-10 inches after collector. I have no exhaust leaks that I can tell. Certainly no Major Leaks.
     
  10. swies

    swies Wish I had more time.

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    I can't figure out how to post a video...
    But;
    After re-wiring the AFR away from the Tach signal, same problem.
    I did talk to Wide-Band and they believe my power is not clean enough and recommended installing a 3300mfd 50v capacitor between the +12vdc and ground wire. I ordered one up (2 for $3.89 on Ebuy) should be here Friday and we will see what happens.
    Getting irritating at this point. Wish I would have spent the extra $40 and got the Innovate or been told about this in the beginning. I noticed they have this info on their website now. It wasn't when I started with this issue.
    Until the caps come in, I will power the AFR with a spare battery and see if it will give proper readings then. No alternator / dirty power then.
     
  11. plumkrazee70

    plumkrazee70 Well-Known Member

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    Can't speak to dirty power. Not sure what that means. You either have 12v or you don't.

    To post a video, the easiest thing to do would be to upload it to youtube and then share the link. If you don't have a youtube account, send me a pm and I send you my email and can host it for you.
     
  12. swies

    swies Wish I had more time.

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    Installed the capacitor as described. No change. Guess I will get ahold of wide band again and see what they say.
     
  13. swies

    swies Wish I had more time.

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    Wide band have me my money back so I went ahead and bought the more expensive AEM X series.
    Guess that it the end of that and this thread.
    I will tackle the new unit on my build thread.
     
  14. mario03srt

    mario03srt Hangin' with The Swamp Rat FABO Gold Member

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    Good Luck!