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Bump/Miss/Hesitation in engine

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    #1

    Bump/Miss/Hesitation in engine

    Hi all,

    '91 Grand Marquis w/ stock AOD tranny and stock remanufactured Jasper 302 engine. Not sure how to exactly say what is going on regarding is it a miss, hesitation, etc but this started last week while driving 75MPH on the interstate on a trip from VA to NC w/ cruise control engaged and A/C off. The engine felt like it had a bump in it where you could feel it inside the car and it started several hours into the trip, so the engine was good and hot. Could have been a miss or hesitation too. I coasted to 65MPH and it went away. On the return trip back from NC to VA driving 65MPH no problems at all. Then this week at 45MPH while the engine is cold but warming up it does it again only I don't have the cruise control on. It went away the further I drove. This seems to occur randomly while lightly feathering the throttle to maintain speed or under slight acceleration to gain speed. No check engine lights are on. Any thoughts on what may be causing this?

    Matt
    Tags: None
    #2
    Check engine LIGHT. Sorry, that irritates me to no end

    How many miles? Does it burn oil? Could be it needs valve stem seals, these lopos tend to foul out the cylinders closest to the firewall. Ashley's old '89 fouled out the driver's side plug and produced the exact same symptoms you described.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

    Comment

      #3
      12,000 miles on the remanufactured Jasper engine. It did use up some oil during the trip although I don't know why it would on a new engine? I had to add about half a quart when I got home.

      Comment

        #4
        Check the plugs and wires. Sounds like ignition misfire to me.
        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

          #5
          I'd definitely check the plugs/ignition like the others said. Also could be intermittent transmission slip, have had it present like this before.

          Comment

            #6
            Thanks. Will have to check the plugs and wires. The AOD does seem to slip on occasion when downshifting out of OD into 3rd while coasting not while accelerating. When it downshifts and you go to give it some gas the engine revs some before 3rd gear seems to engage fully. Have others experienced this at all?

            Matt

            Comment

              #7
              only if the tv pressure is really low.
              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

                #8
                Shall we assume you've checked/replaced your throttle valve bushing? If you're having AOD weirdness that's a definite place to check.

                Comment

                  #9
                  Yes, that bushing has been replaced in the past w/ the bronze one.

                  Comment

                    #10
                    could still have the pressure too low. If its shifting to overdrive under about 40 mph, its probably too low.
                    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
                      It upshifts fine, no problems there. Goes into OD right at 40 under normal conditions or if accelerating onto the interstate it will carry 3rd all the way to 55 before going into OD.

                      Comment

                        #12
                        Sounds reasonable then. When its in overdrive at 30-35 you're likely to get weird slip/shudder crap.
                        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

                          #13
                          When its in overdrive at 30-35 you're likely to get weird slip/shudder crap
                          Could this also occur at higher speeds even up to 75?

                          Comment

                            #14
                            technically yes, but the shudder issue is usually most pronounced between 35 and 45 mph. If the shudder is occurring at 75, then the shudder at 35-45 would be very noticeable. If it's the same-ish feeling up to 75, then it's probably fuel/spark related.

                            Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
                            rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

                            Originally posted by gadget73
                            ... and it should all work like magic and unicorns and stuff.

                            Originally posted by dmccaig
                            Overhead, some poor bastards are flying in airplanes.

                            Comment

                              #15
                              Yeah it's the same-ish feeling whether at 45 or 75.

                              Comment

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