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Lean Misfire, O2 sensors?

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    #1

    Lean Misfire, O2 sensors?

    Yummy. I've noticed a drop in mileage recently. I also noticed a bucking during deceleration. Anyway, I hooked up an exhaust gas analyzer to Vicky and exhaust shows lots of oxygen. Air fuel ratio is about 19.2:1 which is very lean. The analyzer is also picking up hydrocarbons in the exhaust. Before you think it's a vacuum leak, it's not. I have 19.5 inches of vacuum steady. For whatever reason, the computer isn't adding the necessary fuel, or can't add the fuel. We added some propane to the intake, and the car idled much smoother, and the a/f ratio went more rich than lean. Tomorrow I'm gonna see what the O2 sensors are doing, see if they're responding or not. So my question is, if the O2 sensors do turn out to be bad, can I use the O2 sensors from a Lincoln Mark VII (new of course)? Those ones are the ones that have the longer wires right? If the O2 sensors are bad, I was gonna just put the Mark VII sensors on there so I can run them on the new exhaust set up that needs longer wires anyway. Thanks.
    ~John
    Tags: None
    #2
    Autozone sells o2 wires in various lengths specific for our cars.
    ~David~

    My 1987 Crown Victoria Coupe: The Brown Blob
    My 2004 Mercedes Benz E320:The Benz

    Originally posted by ootdega
    My life is a long series of "nevermind" and "I guess not."

    Originally posted by DerekTheGreat
    But, that's just coming from me, this site's biggest pessimist. Best of luck

    Originally posted by gadget73
    my car starts and it has AC. Yours doesn't start and it has no AC. Seems obvious to me.



    ​

    Comment

      #3
      Originally posted by 87gtVIC View Post
      Autozone sells o2 wires in various lengths specific for our cars.
      How long would I need? I'm planning on a setup that includes the motorsport headers and an offroad mustang h pipe, if that helps for length.

      Comment

        #4
        Not sure but I know I seen 15, 10 and 19 inch ones available. Buy big and make sure the harness is not laying on anything hot?
        ~David~

        My 1987 Crown Victoria Coupe: The Brown Blob
        My 2004 Mercedes Benz E320:The Benz

        Originally posted by ootdega
        My life is a long series of "nevermind" and "I guess not."

        Originally posted by DerekTheGreat
        But, that's just coming from me, this site's biggest pessimist. Best of luck

        Originally posted by gadget73
        my car starts and it has AC. Yours doesn't start and it has no AC. Seems obvious to me.



        ​

        Comment

          #5
          Originally posted by 87gtVIC View Post
          Not sure but I know I seen 15, 10 and 19 inch ones available. Buy big and make sure the harness is not laying on anything hot?
          True. Funny though, we were talking about Autozone today in school with how everything can be fixed with an o2 sensor and their vast assortment of o2 sensors.
          And running the car on the dyno was fun!!

          Comment

            #6
            86 has specific oxy sensors, and I'm not entirely sure you can get them in longer lengths. The sensor itself is actually the same as any other 3 wire, but the plug is different. I found that out when I bought 88 Mark VII sensors and they wouldn't plug in. If you change the O2 harness out to an 88-89 one, it works. Its just a short Y shaped thing with two oxygen sensor plugs, the ground connection, and the larger connector to the ECM harness.
            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

              #7
              Originally posted by gadget73 View Post
              86 has specific oxy sensors, and I'm not entirely sure you can get them in longer lengths. The sensor itself is actually the same as any other 3 wire, but the plug is different. I found that out when I bought 88 Mark VII sensors and they wouldn't plug in. If you change the O2 harness out to an 88-89 one, it works. Its just a short Y shaped thing with two oxygen sensor plugs, the ground connection, and the larger connector to the ECM harness.
              Oh. The O2 harness will plug into the main harness though right? Would the '86 Mark VII have the same long wire sensors?

              Comment

                #8
                Was the car idling with an afr of 19.2? If that was with it driving, that is dangerously (and I mean dangerously) lean.

                If its at idle, thats lean, but most stuff runs lean at idle.
                **2012 Ford Mustang Boss 302: 5.0/ 6 spd/ 3.73s, 20K Cruiser
                **2006 MGM,"Ultimate": 4.6/ 2.73/ Dark Tint, Magnaflows, 19s, 115K Daily Driver
                **2012 Harley Davidson Wide Glide (FXDWG):103/ Cobra Speedsters/ Cosmetics, 9K Poseur HD Rider
                **1976 Ford F-150 4WD: 360, 4 spd, 3.50s, factory A/C, 4" lift, Bilsteins, US Indy Mags, 35s Truck Duties

                Comment

                  #9
                  Originally posted by P72Ford View Post
                  Was the car idling with an afr of 19.2? If that was with it driving, that is dangerously (and I mean dangerously) lean.

                  If its at idle, thats lean, but most stuff runs lean at idle.
                  Was running lean on the dyno, and at 2500rpm, in neutral as well. We added some propane and the engine idled much smoother. A/F ratio was much better. Tested the O2 sensors today, they're retarded. So I'm gonna need a new set.

                  Comment

                    #10
                    Originally posted by 86VickyLX View Post
                    Oh. The O2 harness will plug into the main harness though right? Would the '86 Mark VII have the same long wire sensors?
                    yes and probably. Or, you could get generic sensors with no plugs and splice the plugs from your sensors on, giving you approximately double length sensors that are plenty long enough to do whatever you need.
                    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

                      #11
                      can you measure fuel psi?

                      Comment

                        #12
                        Originally posted by jayh View Post
                        can you measure fuel psi?
                        Yes, with it running it's 30psi. The fuel flow rate is also good.

                        Comment

                          #13
                          30 psi with or without vacuum? should be 30-35 with, and 40-45 without.
                          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
                            Originally posted by gadget73 View Post
                            30 psi with or without vacuum? should be 30-35 with, and 40-45 without.
                            Sorry. 30 with vacuum, 40 with the vacuum line on the regulator disconnected.

                            Comment

                              #15
                              while driving/under load?

                              Comment

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