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Running lean condition (2nd try)

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  • Running lean condition (2nd try)

    Guys,

    As mentioned before in this thread: http://www.s14.net/forums/showthread...&threadid=6018

    I am trying to find out why I see AFR's going up to 20 at part throttle. I have checked the fuel pump (very low noise level) under the rear seat, cap, rotor and spark plugs. All are in excellent condition AFAIK.

    The question remains if somebody can have a look at my MAXX controller log file and tell me if the DME is getting the right value of fuel to inject when the engine is running lean.

    On several occasions in the log file you will see the trottle% at 12.5 to 12.9% (closed throttle) and idle at around 850-950 rpm with an AFR of 19.. Other instances show a lean condition at around 1250 to 1750 rpm...

    I have uploaded the log file for your scrutiny at: http://www.xs4all.nl/~adwo/Alpha-N%2...s/04052123.ZIP

    I have a feeling the adjustable FPR I installed is going south, but would like to be sure!

    Thanks in advance!!

    Adwo

    Forgot to mention: the log file is sorted by RPM (low --> high)
    Last edited by Adwo; 05-26-2004, 01:51 AM.

  • #2
    Adwo,
    please read my post above Lambda


    Goodbye M3, you served me well.

    Comment


    • #3
      Try checking for leaks in the exhaust. Even downstream of the O2 sensor can affect it! It's gotta be sealed.

      Stan

      Comment


      • #4
        @Uwe,

        The Techedge unit I have is working flawlessly and has no influence on the DME, it's stand alone...

        @Stan,

        Thanks for the advice. However, the car stumbles and hesitates when the lean condition is appearing, so it's not the sensor, but something else...

        Regards,

        Adwo

        Forgot to mention I have a catless Evo 2 so the normal O2 sensor is not present...

        Comment


        • #5
          what happens when you richen up the mixture via the MAXX software?

          It still stays lean regardless?

          Comment


          • #6
            I have not tried that yet. What can you achieve by doing that? (as the car is running correctly after I shut down and restart the car..). The Maxx unit is not the problem...

            The syptoms occur a couple of minutes after start up, no difference in engine hot or cold. In the log file you will see that the Maxx unit is always sending around the value of 42 to the DME when the AFR goes to 20 (in other instances it's at 14.7 AFR with the same 42 sent to the DME).

            That's why I think it's a fueling problem caused outside the Maxx unit...

            Adwo

            Comment


            • #7
              Originally posted by Adwo
              I have not tried that yet. What can you achieve by doing that? (as the car is running correctly after I shut down and restart the car..). The Maxx unit is not the problem...

              The syptoms occur a couple of minutes after start up, no difference in engine hot or cold. In the log file you will see that the Maxx unit is always sending around the value of 42 to the DME when the AFR goes to 20 (in other instances it's at 14.7 AFR with the same 42 sent to the DME).

              That's why I think it's a fueling problem caused outside the Maxx unit...

              Adwo
              I understand....my car was doing that for a while...i couldnt figure out what it was. I replaced my FPR, ICV, Fuel Pump Relays, Throttle body gaskets, Injector seals.

              It would run fine in the mornings and then in the afternoon after sitting in the sun all day it would run way lean at any partial throttle or below 4k rpm.

              This problem seems to have gone away since i re-installed my evo aibox and put the air temp sensor in it and got the maxx fully tuned on a dyno.

              Check your connections again...make sure nothign is loose.

              My car is still running slightly wierd...im going to get the injectors balanced and blueprinted. See if that helps at all.

              Looking at my spark plugs, my car appears to be running very well now though. I only have issues at low rpm big throttle input.

              Comment


              • #8
                Adwo, Id be happy to look at your log file but please
                send me the ORIGINAL one, not an edited version.

                the first thing I noticed is that your car comes up
                to revs after first start very slowly.

                I know you have 284/276 cams whether or not you
                notice too much when adjusting the bypass,
                it does have an effect on the AFR, ICV setup map,
                and fuel map at idle rpm. it takes a few tries to get this
                setup right so that its correct on cold and warm start.

                if you want to send a log file where you are driving
                at part throttle and have the lean condition you can
                do that too. please send the map along with the log file(s).

                I just setup up holgers engine on tuesday and it ran really
                well, but he had the same problem with idle at cold.
                We have to set it a few times before its right and you cant
                do it when the engine is already warm.

                John
                PS. we have his FPR set at 4.6 bar. I have the maps for it.
                Last edited by John; 05-26-2004, 08:56 AM.

                Comment


                • #9
                  John,

                  Thanks for the offer. I screwed the original log file, so I will have to make another one.. Will take some time as I am reinstalling the hoses the the carbon box and replacing the brake fluid...

                  I assume you mean Holger with the Evo 2? Would be interesting to have his map for comparison...

                  Is your Matlab application an exe or do you need the complete Matlab software... Because that's rather expensive! ;-)

                  Adwo

                  Comment


                  • #10
                    no it was his blue race car. but it only has 284/284 schrick
                    cams. that engine with a CR gear box and 3.73 diff
                    and given its stripped, made it pull nice.

                    if I do a graphical plot of your log file then yes thats with
                    matlab app I wrote but its not a big deal. very simple
                    tool actually. perhaps one of your friends
                    has matlab anyway all the tool does is plot
                    various selected signals over a common time axis
                    or in mulitple plot windows and allows things like zoom
                    and pan. Its just a quick way to compare signals graphically.
                    if you know what you are looking at, you can also just look
                    at the plain numbers.

                    John

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