Thought It Was Fixed Still Runnin Rich Code 91 Only

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by joedirt76, Mar 4, 2014.


  1. joedirt76

    joedirt76 Member

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    I don't think this is a normal problem ,this is gonna be long but please read and help , after lots of electrical test part swapping and replacing I am still running rich . as of now I am not using the pms it is on the bench stock computer only (a9p) , 36 # injectors replaced with 30# , correct calibration tube being used, maf properly cleaned , spark plugs are autolite 3924 gapped at .054 , base idle correct and tps at .99 , timing 14 degrees,o2 sensors replaced, o2 sensor harness completely continuity checked, all grounds checked and good , maf,map,and tps sensor checked and good . after all that I am pulling (code 91 only) and it just wont go away , ive cleared codes in ever fashion including battery disconnect to clear kam redrove reran test and 91 just wont go away , car starts and runs ok but is runnin rich enough the smell bothers u at idle , heres the kicker after parts replacement injectors , computer, plugs, and bypass pms ,the car ran so perfect I couldn't believe it !! but only lasted for that one run the next time I cranked 2 days later it was right back to runnin rich , please please help I am at total lost at this point , thanku in advance
  2. 84Ttop

    84Ttop They make new pistons every day, so why worry? SN Certified Technician Mod Dude

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    Are you using a C&L Meter?
  3. joedirt76

    joedirt76 Member

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    I am currently, I know everyone says there junk and pro-m supposed to be the way to go , due to lack of funds I haven't purchased one yet. I certainly don't know it all and hope to not offend anyboby in my lack of knowledge on some of this , but how can the meter alone throw that code , theres nothing electrical about it I would think maf sensor before the meter but then why not code 41 with it ?
  4. joedirt76

    joedirt76 Member

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    just to be clear my mass air flow is a 76mm c&l with tube 099 for 30# injectors , the meter itself that plugs into harness is a stock meter
  5. Grabbin' Asphalt

    Grabbin' Asphalt Mustang Master

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    IMO the meter is critical in the amount of air/fuel mixture, .....so it is the BIG part on the air side to determine the Fuel side, any screw up in that dept and problems abound.
  6. Bullitt347

    Bullitt347 man bewbs please...

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    The reason C&L meters have this issue is that they are trying to "trick" the stock MAF sensor into reading a certain amount of air flow. The stock sensor was calibrated for 19 lb/hr injectors, with the C&L meter, the sensor is still calibrated for 19 lb/hr injectors, but C&L is using a different sampling tube to get a different air flow across the sensor to offset the larger fuel injectors. Sometimes it is close enough, sometimes not so much.
  7. joedirt76

    joedirt76 Member

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    good explanation that makes sense , but how is a pro-m gonna solve the problem if im still using 30# injectors and the sensor is still calibrated for 19#
  8. Bullitt347

    Bullitt347 man bewbs please...

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    Because the Pro-M does not use a MAF sensor calibrated for 19 lb/hr injectors. They actually calibrate the sensor to the size injector you are using so there is no "tricking" of the sensor. The electronics inside the sensor have been changed (the air/fuel map or table is recalibrated) instead of changing how the air flows past the sensor.
    A5literMan likes this.
  9. joedirt76

    joedirt76 Member

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    ahhhhh haa, 10/4 guess ima have to invest your the first one who has explained it in a way that I understand , makes total sense now especially being it has always ran rich since the build , I will get one, and I will reply with a update to this thread as soon as installed !! thanks a bunch
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  10. Bullitt347

    Bullitt347 man bewbs please...

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    Glad I could help, keep us posted.
  11. joedirt76

    joedirt76 Member

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    was gonna wait till weekend to give better update , but bought pro-m 80 installed last night , put computer back in that I let sit on bench and decay in codes hookup up scanner cleared codes again and turned the key , right away running completely different and as much as I hate to say its worst after meter change,still running rich I didn't mess with it long only long enough to warm up and run a koer to pull codes , 91 is gone for now only pulled 3 others and that's the stuff unplugged egr,thermatic etc. but still running rich , im starting to wonder if im just overfueling somehow ,too much fuel pump,or jacked up regulator maybe ?
  12. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    What were the numeric codes?
  13. joedirt76

    joedirt76 Member

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    was in a hurry didn't write them down ,but I do remember 94, I will have better update and info this weekend ! work has me tied down till then
  14. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    to clarify, you now have a pro m meter calibrated for 30# injectors along with 30# injectors?
  15. joedirt76

    joedirt76 Member

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  16. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    do ou have a wideband o2 sensor and an afr gauge?
  17. joedirt76

    joedirt76 Member

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    No , just replaced o2's with new stock Bosch ones
  18. joedirt76

    joedirt76 Member

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    Was gonna try next checking my fuel pressure with different gauge just to confirm if pressure is correct or not , right now I have small gauge tapped right into pressure regulator but want to rule out if that gauge is defective or not
  19. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    If no wideband how are you sure its rich?
  20. joedirt76

    joedirt76 Member

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    FUMES, bout died lastnite just letting it warm up lol

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