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How do I stop my car from running lean?

Discussion in 'Fox-Body Cobras' started by RyneLightning, Feb 9, 2010.

  1. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    I've done some research, and concluded that the backfiring, and the hesitation, and the slugish behavior of my engine is from running to lean, does this sound right? How do I fix my air/fuel ratio to stop it from running lean?

    Sometimes the car runs great, and just really gets up and goes, and then at other times, it almost dies down, or even goes slower @ WOT.

    Someone please help!
    I appreciate it.

    Ryne:shrug:
     
  2. RDJ

    RDJ ZERO shits given Established Member

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    With the amount of information you have provided, the only way to do it is to move it out of the gargage, look at it very sternly and say "you are not going back into the garage until you quit running lean!"


    seriously how is anyone supposed to help you with that pitiful amount of info? what gas are you using? what mods (if any) are on the car? what have you tried so far? what does your mechanic say?
     
  3. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    MODS INCLUDE:

    Stock 302 cobra motor - Recently Freshened up(less than 15k on it)
    - Heads; where changed to a pair of E7 heads that where ported significantly and had 1.94 / 1.60 valves installed. Valve springs where changed to some comp cams.
    - Heads also have 1.7 stud mount roller rockers (Yes the heads are converted to stud mount)
    - Cometic Head gaskets
    - Fuel Pressure Gauge on fuel rail
    - Adjustable Fuel Pressure Regulator
    - MAC long tube headers
    - Flow master mufflers
    - BBK off road H-Pipe
    - C&L 76mm MAF cal'd for 30lb injectors.
    - 30 pound injectors


    Thats all thats done to the engine
     
  4. 93Cobra#2771

    93Cobra#2771 SVT God Established Member

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    1. Has the condition just started or been present since the motor was freshened up?
    2. If it just started have you made any changes?
    3. Have you Checked for any engine codes?
    4. Did you get the correct sampling tube for the maf and the x3z computer specific for the Cobra?
    5. What is your fuel pressure set at?
    6. Have you checked for vacuum and exhaust leaks?
     
  5. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    I just bought the car last week. I also didn't do any of the mods, thats just all I know that is done to it. And I'll check that idle fuel pressure in the morning, its too cold to go out now. I'll try to run to autozone tomorrow at lunch and have that code ran too.
     
  6. Liv4Spd

    Liv4Spd New Member Established Member

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    :lol1:
     
  7. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    Fuel pressure @ idle is 28psi, and autozone doesn't run codes earlier then a 96.
     
  8. 93Cobra#2771

    93Cobra#2771 SVT God Established Member

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    But, you can actually get an older style code puller for under $20 bucks. You absolutely need to get the codes pulled, as it will help head in the right direction. Something as simple as an O2 not switching could be the issue (would ping a code) or something as complicated as an O2 reaching max fuel adjustment (vacuum or exhaust leak) can be found that way.

    Could be something mechanical, such as a burnt valve, or dirty maf element, etc. Lot of "could be's" happening, so we need to start eliminating possibilities. That starts with pulling the codes. :D

    Fuel pressure is a bit low, but not enough to cause what you have.
     
  9. buddha93

    buddha93 Well-Known Member Established Member

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    Ya, your about 10psi off on your FP, but like Richard said I'm not so sure it's the issue. I wonder if the previous owner cranked it down to overcome an issue of some sort.

    Those C&L meters can be a little quirky too, but once you clock to their sweet spot, they usually work fine.

    Like Richard said, I'd check the EEC for codes. You can use a simple jumper wire to read the codes via the light on the dash, but it can be a bit tricky if you've never done it before.
     
  10. 93Cobra#2771

    93Cobra#2771 SVT God Established Member

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    I'm figuring that the FP was dropped since the injector is so big for the the application. The most that car should have on it is a 24# injector. And C&L plus X3z is a mismatch at best, unless the EEC was swapped to the A9L family.

    From the description, it actually sounds more like it is running rich than lean. Have you pulled the plugs just to see what they look like? If running rich, they are going to be black and sooty, if lean they are going to be very white with specs of metal on the electrodes.

    You could even have an issue with a single plug or wire. That plays havoc with the fuel injection, as it tries to compensate for a single cylinder. I had a plug boot get hot enough to crack and cause an occasional misfire on that cylinder. Took me quite a while to track that one down, let me tell you. Intermittant problems are tough to tackle.
     
  11. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    The light doesn't stay on, it is always off when I crank it up, but then after about 10 minutes it comes on everytime, the guy said it is because of the full exhaust and it has no smog detection. As soon as I am able to, hopefully tonight, I'll check the plugs.

    But does it make sense for the car to not hesitate when it is cold, and then as it heats up get worse? Because it seems to always be WAY better before the engine heats all the way up.
     
  12. 93Cobra#2771

    93Cobra#2771 SVT God Established Member

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    That is normal for the CE light.

    Full exhaust with no smog will not trip the CE light. He was wrong.

    Makes perfect sense that it acts fine when cold. Car is not running off the o2 sensors at initial start up. As it warms up it goes closed loop and uses o2s to trim the injector pulsewidth.

    We will get this worked out. :)
     
  13. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    Alright, if I have time I'll check those plugs and update you tonight, but its looking like its going to be a LATE night. At any rate, I can check them tomorrow, and hopefully find somebody to pull the code for me tomorrow at lunch time.

    I'm not too knowledgeable about this engine yet (used to that lightning 5.4), but are you leaning towards the o2 sensors being bad?
     
  14. 93Cobra#2771

    93Cobra#2771 SVT God Established Member

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    To little info to lean toward anything right now. There is a method to my madness. :)
     
  15. buddha93

    buddha93 Well-Known Member Established Member

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    Yep, gotta agree with that.....lol!

    Whatever you've got going on, it doens't sound to hard to figure out. It sounds like it only be a few things. I don't think it's your O2's though, but it's hard to say for sure. Even if it's throwing codes, sometimes those will lead you down the wrong path.

    The FP setting makes me think the previous owner was trying to "tune" something out and common sense would tell you it was rich somewhere.

    While the 30's are a bit big for that application, if it's tuned right they won't present any issues. The EEC will adjust and all's good. For example, I run 50's on the street with no problems whatsoever. It idles and drives like stock and even passes a sniffer test here in Missouri.

    I think Richards call on the Cobra processor and the C&L is the right assumption. You need to take a look at the sampling tube, verify that and verify what EEC is behind the kick panel.
     
  16. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    Me and my dad took it out a little while ago, and he suggests bad timing. I'm not sure about that, but could that also be a solution?

    And I am confused on the sampling tube...as in (what is it?) and (where is it located?). I'm going to pull the plugs tomorrow and see what they have to say, my suspision is that it is running rich, now that I am getting more into it, it feels like it is loading up.....IDK thought, time will tell.

    I'll keep you updated on what I see.
    Ryne

    THANKS GUYS!:beer:
     
  17. buddha93

    buddha93 Well-Known Member Established Member

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    Do the easy stuff first, like timing, plugs, etc. You don't have to pull every single plug, but 3 or 4 will give you a good idea.

    The sampling tube is in the meter itself....something unique to C&L's. If you have the stock EEC, the tube should be blue in color, number 102. That is for a 24lb injector, but is supposed to work with 30's and the Cobra processor.
     
  18. RyneLightning

    RyneLightning When The Blower Spins.... Established Member

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    WTF! Ok, I pulled the meter out, turns out it has the red sensor in it!!! That is for the 38lb injectors if i'm not mistaken, so does this mean that it is sending too much gas (hence it thinks its sending to 38s and it is really only sending to 30s?)
    Ill pull a couple plugs and post back in a few
    Ryne
     
  19. buddha93

    buddha93 Well-Known Member Established Member

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    F the plugs. Verify what tube you have with C&L, and I'd double check the EEC too. The red tube is the correct one if the car has an A9L. Is there a number stamped on it also?

    Honestly, and this is just my experience and opinion, I'd ditch the C&L and go with an electronically calibrated meter. The C&L's can and do work, but the other meters just work soooo much better and aren't as fickle when adding power adders and making other engine modifications.
     
  20. 93Cobra#2771

    93Cobra#2771 SVT God Established Member

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    x2 on that. The C&L's are the least favorable unit to go with. You also need to verify FOR SURE that you have 30# injectors. You ALSO need to verify which EEC you have, and visually inspect whether it is chipped or not.
     

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