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    #1

    Rough start when hot

    My 90 Grand Marquis has had this problem from time to time where it'll start up and run fine when it's cold but if I park the car when the temp gauge is around the M in "NORMAL" it starts to have problems, not every time, but enough worry me. Now, if I start it right back up after parking, it's fine, but if I go into the store for forty five minutes or something and come back out, that's when it happens.

    I turn the key and it cranks a few times like normal, then fires up, BUT it immediately starts to sputter out and die. If I start it up and give it a couple good revs, it'll sound kind of rough at first, but eventually it evens out and starts running fine again. Recently my wife has been driving the car and it did it to her but it REALLY didn't want to start back up again. Eventually I told her to start it up and continually press the gas pedal down just a little bit and leave it for five seconds, give it a good rev, then let off the gas. It worked, she drove home with no noticeable changes in the vehicles performance.

    It seems like it's not getting enough gas, I don't know though, fuel pump, tank, and filter are two years old. Bum fuel Pump? TFI module? ECT? Any help pointing me in the right direction, or away from the wrong directions, would be very much appreciated!


    Oh yeah, and I've also been noticing my AC wanting to cut out sometimes when the temp gauge is on M and the problems almost definitely occur if I park it when the AC is out. Might be unrelated.
    Last edited by BuffaloRider; 05-09-2015, 11:04 AM.

    Tags: None
    #2
    Could be either or a bad temperature sensor. Check the ofi mirror is the sticky for info on testing them.

    posting from mah phone. plz to be forgiving bad speeling.
    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

      #3
      Well damnit, too damn busy today to even get into it.

      The more I read the more things it could be. Maybe a faulty fuel injector is leaking excess fuel into the combustion chamber or something. If that's the case, maybe I'll get to the bottom of it when I take my upper intake manifold off this summer. But that wont be til we get a car for my wife to drive.

      I might be able to check for a vacuum leak today, that always causes shit to act funny, right?

      Comment

        #4
        Can, but usually doesn't affect starting. I'm voting on coolant or air temperature sensor. Couple minutes with a voltmeter will tell you. Usually when they are off, its off enough that you know even without any means of measuring temperature. if it shows the coolant is being either extremely cool or very hot, its probably bullshit. Same with the air, its not likely to be more than 50 degrees F hotter than outside temperature, and its pretty much guaranteed to not be colder than outside air.

        http://www.grandmarq.net/oldfuelinjection/page10.html


        ACT and ECT are the ones you're after. With the engine running and fully warmed up, coolant should be in the 190-200 range, and air temp is probably somewhere around 120-160.
        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 have that problem with my 88... the ACT heat soaks and needs a few turns to pump in enough air to cool it off enough to fire right. This is usually in August though when it's 100+ outside and the coolant is at least 200F when I shut off. (typically 210-ish.) Usually don't have that issue in the cooler months.

          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

            #6
            I couldn't find any noticeable vacuum leaks, for the record.

            I'll have to look into the ACT and ECT to see if that's the culprit. I have a multimeter but I honestly don't know how the hell to use it properly, and I won't have time to mess with anything for a few days anyways so I can take that time to figure out what I'm doing. Testing electronic components for volts and stuff is like alien talk to me, forgive my ignance. That's partially why I've been putting off a 3g swap and headlight upgrade for so long.

            Comment

              #7
              Originally posted by BuffaloRider View Post
              I couldn't find any noticeable vacuum leaks, for the record.

              I'll have to look into the ACT and ECT to see if that's the culprit. I have a multimeter but I honestly don't know how the hell to use it properly, and I won't have time to mess with anything for a few days anyways so I can take that time to figure out what I'm doing. Testing electronic components for volts and stuff is like alien talk to me, forgive my ignance. That's partially why I've been putting off a 3g swap and headlight upgrade for so long.
              pull the plug with the car off (preferably cold first, then warm it up and test again) and put the meter on OHM (resistance) setting of 20K and measure across the pins. Doesn't matter which pins. The sensor is a resistor that varies with temperature. Compare to the charts on the Old Fuel Injection mirror:
              ECT Chart: http://www.grandmarq.net/oldfuelinjection/page28.html
              ACT Chart: http://www.grandmarq.net/oldfuelinjection/page29.html

              The temps you'll be looking for with the ECT are whatever the outside temp is when "cold" and then operating temp after driving around a bit (190-210). If it's close to the chart on both counts, the sensor is fine. The ACT should be the outside temp when cold and the outside temp +20 or so when warm IIRC. If the ACT shows exactly the same as the ECT when hot, it's sensing the intake manifold instead of the air and should be changed.

              If either do not change value, are shorted (below 1 ohm), or open (over 200K ohms), they're bad and should be changed.

              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

                #8
                Or for a few bucks you could change both sensors. Not a fan of just replacing parts but if they are original and you can get OEM or good aftermarket ones.....


                "Hope and dignity are two things NO ONE can take away from you - you have to relinquish them on your own" Miamibob

                "NEVER trade your passion for glory"!! Sal "the Bard" (Dear Old Dad!)

                "Cars are for driving - PERIOD! I DON'T TEXT, TWEET OR TWERK!!!!"

                Comment

                  #9
                  Thanks for the links sly!

                  Originally posted by miamibob View Post
                  Or for a few bucks you could change both sensors. Not a fan of just replacing parts but if they are original and you can get OEM or good aftermarket ones.....
                  That's what I figured, I've already got them paid for and shipped. But, I do need to learn to use a multimeter sometime though, so I've been messing around with that and stuff. I set it to ohms, 20k, touched the black to one pin, and the red to the other pin, and it wouldn't change, still read 1, on both the ACT and ECT. If i touch the probes together it changes to 0, but when put to the pins on the sensors, nothing. I'm probably doing something wrong lol

                  I'll figure it out and update this thread when I get the new sensors in and see what that does for me.

                  Comment

                    #10
                    Originally posted by BuffaloRider View Post
                    Thanks for the links sly!



                    That's what I figured, I've already got them paid for and shipped. But, I do need to learn to use a multimeter sometime though, so I've been messing around with that and stuff. I set it to ohms, 20k, touched the black to one pin, and the red to the other pin, and it wouldn't change, still read 1, on both the ACT and ECT. If i touch the probes together it changes to 0, but when put to the pins on the sensors, nothing. I'm probably doing something wrong lol

                    I'll figure it out and update this thread when I get the new sensors in and see what that does for me.
                    The way you described what you did sounds like correct procedure to me. As long as the metal probes of the meter were each touching one of the pins on the sensor you should have read something that was within the range these guys were telling you. It sounds like you have a digital multimeter. That 1 that shows up if the test leads/probes are not touching anything, should be on the left of the screen iirc. It basically tells you that the resistance being measured is too high for the range that you are in. Since 20k is what these guys told you to set the meter to, it sounds like that sensor is in need of replacement.
                    Just for grins, if you set it to a higher range (not sure if there is a higher range in this case, 200k?) and you get a reading then you are definitely outside of the acceptable value range, based on what these guys have said, and replacing that sensor would be the correct call.
                    Last edited by VicCrownVic; 05-13-2015, 08:45 AM.
                    Vic

                    ~ 1989 MGM LS Colony Park - Large Marge
                    ~ 1998 MGM LS - new DD
                    ~ 1991 MGM LS "The Scab"
                    ~ 1991 MGM GS "The Ice Car"

                    Comment

                      #11
                      Or set the meter to a higher range for a good test. Since you have ordered them you should be set (assuming one or both of them were the original issue).


                      "Hope and dignity are two things NO ONE can take away from you - you have to relinquish them on your own" Miamibob

                      "NEVER trade your passion for glory"!! Sal "the Bard" (Dear Old Dad!)

                      "Cars are for driving - PERIOD! I DON'T TEXT, TWEET OR TWERK!!!!"

                      Comment

                        #12
                        Originally posted by miamibob View Post
                        Or set the meter to a higher range for a good test. ...
                        LOL, that's what I was trying to say in my last line. I felt kind of silly saying it since it will not be of much benefit for troubleshooting, but it will be a good step to become a little more familiar with how the multimeter works.
                        Vic

                        ~ 1989 MGM LS Colony Park - Large Marge
                        ~ 1998 MGM LS - new DD
                        ~ 1991 MGM LS "The Scab"
                        ~ 1991 MGM GS "The Ice Car"

                        Comment

                          #13
                          Originally posted by VicCrownVic View Post
                          LOL, that's what I was trying to say in my last line. I felt kind of silly saying it since it will not be of much benefit for troubleshooting, but it will be a good step to become a little more familiar with how the multimeter works.
                          +1. Just wanted to make sure it got through.


                          "Hope and dignity are two things NO ONE can take away from you - you have to relinquish them on your own" Miamibob

                          "NEVER trade your passion for glory"!! Sal "the Bard" (Dear Old Dad!)

                          "Cars are for driving - PERIOD! I DON'T TEXT, TWEET OR TWERK!!!!"

                          Comment

                            #14
                            +1 set to 200K... if it's cold where you are, the resistance may be over 20K when cold.

                            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
                              Originally posted by miamibob View Post
                              +1. Just wanted to make sure it got through.
                              Yeah, sometimes it needs to be beaten into my big dumb head lol.

                              Comment

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