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    #3 spark plug chalky black... and misses

    its just the #3 spark plug thats chalky black like its running rich, and your can feel it missing at lower RPM's, and up in the high revs you don't notice the miss in that cylinder. distributer is a year old and plug wires are a few months, all good pieces too, checked the contacts in the cap and it all looks good.

    I am suspecting a leaky injector causing it to run rich... And at high revs i don't notice the miss so much because of the increased demand for fuel vs the missing at low revs when its getting way more fuel than it needs? I did have 1 of the 19lb injectors before the build that was sticking before i cleaned it out, so i wouldn't be surprised if that was the culprit.

    is thier any way of testing this injector out while its in the car to see if its stuck open? Or will i have to take off the plenum and just swap the injector.
    Finally have an on the books porting/custom fab business!
    HO bottom end,GT40Ps,cut/welded/ported upper+lower GT40 intakes,Comp XE258 cam,MS3X megasquirt computer,8 LS2 coils,2 dry systems + a 3rd wet,3 core rad w fans..1100hp Lentech WR AOD,custom 4" aluminum/moly Dshaft,custom rear/back half chassis adjustable 4link,wilwood 4 piston,moser 9" axles,locker, M/T 30x12's,4 staged fuel pumps,100lbs sound insulation,power/remote everything,2000W sound.4480lbs. 4.5s 0-60,12.8 1/4


    #2
    Originally posted by merc91 View Post
    its just the #3 spark plug thats chalky black like its running rich, and your can feel it missing at lower RPM's, and up in the high revs you don't notice the miss in that cylinder. distributer is a year old and plug wires are a few months, all good pieces too, checked the contacts in the cap and it all looks good.

    I am suspecting a leaky injector causing it to run rich... And at high revs i don't notice the miss so much because of the increased demand for fuel vs the missing at low revs when its getting way more fuel than it needs? I did have 1 of the 19lb injectors before the build that was sticking before i cleaned it out, so i wouldn't be surprised if that was the culprit.

    is thier any way of testing this injector out while its in the car to see if its stuck open? Or will i have to take off the plenum and just swap the injector.
    Could do a fuel pressure test.
    Could also do a cylinder balance test with the computer...
    You know how to run a self test right?

    Comment


      #3
      After the Engine ID code (light flashes 1/2 the amount of cylinders in the engine) You can step on the brake pedal and rotate the steering wheel. As for the dynamic response check, the SEFI cars such as our cars, and the mustangs, do not have a dynamic response check. Instead, we have the ability to do a cylinder/injector balance test, which will numerically kill each injector to check for a drop in engine RPM. To do the balance test, the regular running test should have already been completed. That means, the light isn't flashing any more codes/repeating any codes. After the light has stopped flashing, step on the gas slightly, and then take your foot off of it. The idle of the engine should increase. It is now in cylinder balance test mode. Do not do anything to change the engine rpm or it will stop the test. It will go through each injector. You will notice that the engine will appear to run rough during this test. This is normal as one cylinder is being killed each time. After it has shut off each injector, the idle will return down to normal, or close to normal, and flash a code at you.
      The corresponding codes to the cylinder balance test are as follows:
      *--------------------10 (Cyl 1 has failed)
      **-------------------20 (Cyl 2 has failed)
      ***------------------30 (Cyl 3 has failed)
      ****-----------------40 (Cyl 4 has failed)
      *****----------------50 (Cyl 5 has failed)
      ******---------------60 (Cyl 6 has failed)
      *******--------------70 (Cyl 7 has failed)
      ********-------------80 (Cyl 8 has failed)
      *********------------90 (All Cylinders pass!)
      *********..*********--------99 (Engine has not learned to idle)

      Comment


        #4
        Swap the injector and see if the symptom follows the injector. If you put it on cylinder 1 (for example) and cylinder one then gets the issue, you have an injector issue.

        85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
        160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
        waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

        06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

        Comment


          #5
          Originally posted by johnunit View Post
          Swap the injector and see if the symptom follows the injector. If you put it on cylinder 1 (for example) and cylinder one then gets the issue, you have an injector issue.
          He just wants to check it without taking it all apart...
          but this is a good idea too.

          Comment


            #6
            ah, yeah. forgot how much more involved pulling an injector is on an EFI 5.0 than the 4cyl cars where most of my EFI experience is.

            85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
            160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
            waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

            06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

            Comment


              #7
              unplug the injector and see what happens
              Builder/Owner of Badass Panther Wagons

              Busy maintaining a fleet of Fords

              Comment


                #8
                she's burried way under the plenum with my heter hose tucked in thier also so i'll have to take the plenum off anyways to unplug the harness. I know its just #3 running rich and the electrical ignition all seems ok so that pretty much just leaves the injector i'm thinking.

                I had no idea about the self test thanks, i'll check it out and run the test on my mustang A9P computer and see if anything turns up.
                Finally have an on the books porting/custom fab business!
                HO bottom end,GT40Ps,cut/welded/ported upper+lower GT40 intakes,Comp XE258 cam,MS3X megasquirt computer,8 LS2 coils,2 dry systems + a 3rd wet,3 core rad w fans..1100hp Lentech WR AOD,custom 4" aluminum/moly Dshaft,custom rear/back half chassis adjustable 4link,wilwood 4 piston,moser 9" axles,locker, M/T 30x12's,4 staged fuel pumps,100lbs sound insulation,power/remote everything,2000W sound.4480lbs. 4.5s 0-60,12.8 1/4

                Comment


                  #9
                  sigpic


                  - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

                  - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

                  - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

                  Comment


                    #10
                    Originally posted by merc91 View Post
                    she's burried way under the plenum with my heter hose tucked in thier also so i'll have to take the plenum off anyways to unplug the harness. I know its just #3 running rich and the electrical ignition all seems ok so that pretty much just leaves the injector i'm thinking.

                    I had no idea about the self test thanks, i'll check it out and run the test on my mustang A9P computer and see if anything turns up.
                    good luck!

                    Comment


                      #11
                      it may be worth it to go to crappy tire and grabe one of them 40dollar ford code readers, for OBDI. i had one before i got my more expensive scanner. it will do cylinder blance tests.

                      1981 Mercury Marquis Brougham 2-Door 302/ 5-speed -special blend (GMGT)
                      1987 Lincoln Mark VII 5-speed (Errand runner)
                      1989 Mercury Grand Marquis (Base Runner)
                      2007 Lincoln Town Car Signature Limited (Hustlyn)
                      2011 Ford Crown Victoria Police Interceptor (Down with O.P.P)

                      Comment


                        #12
                        Originally posted by marquisman View Post
                        it may be worth it to go to crappy tire and grabe one of them 40dollar ford code readers, for OBDI. i had one before i got my more expensive scanner. it will do cylinder blance tests.
                        Yeah, but a wire grounding the pigtail and a check engine light will do it for cheaper. Granted it takes longer, but it's free

                        Comment


                          #13
                          The only kind of code reader I'd buy is one with a digital display. A lot of the cheap ones either have an LED that you count the blinks on, or a beeper that you count the tones on. Its exactly the same as grounding the wire, only it costs more.
                          86 Lincoln Town Car (Galactica).
                          5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                          91 Lincoln Mark VII LSC grandpa spec white and cranberry

                          1984 Lincoln Continental TurboDiesel - rolls coal

                          Originally posted by phayzer5
                          I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                          Comment


                            #14
                            the one i was talking about has the digital display. and it come with the book that lists all codes. was the best 40bucks i spent, when i got into EFI panthers

                            1981 Mercury Marquis Brougham 2-Door 302/ 5-speed -special blend (GMGT)
                            1987 Lincoln Mark VII 5-speed (Errand runner)
                            1989 Mercury Grand Marquis (Base Runner)
                            2007 Lincoln Town Car Signature Limited (Hustlyn)
                            2011 Ford Crown Victoria Police Interceptor (Down with O.P.P)

                            Comment


                              #15

                              FTW
                              2020 F250 - 7.3 4x4 CCSB STX 3.55's - BAKFlip MX4
                              2005 Grand Marquis GS - Marauder sway bars, Marauder exhaust, KYB's
                              2003 Marauder - Trilogy # 8, JLT, kooks, 2.5" exhaust, 4.10's/31 spline, widened rear's, metco's, addco's, ridetech's 415hp/381tq
                              1987 Colony Park - 03+ frame swap, blown Gen II Coyote, 6R80, ridetechs, stainless works, absolute money pit. WIP

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