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CFI random stall on decel/quick stop when hot

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    #16
    Originally posted by Hillbillycat View Post
    I could also think of the vacuum throttle kicker not doing it´s job quite right i.e. leaking. I can pull vacuum on this dashpot thing and the plunger extends. It DOES NOT hold vacuum, it just extrudes while a vacuum source is applied.
    The throttle kicker is supposed to leak some, atleast that was what I was told here. Not sure if the throttle kicker is supposed to do anything other than raise the idle when the AC is running. When fully functioning, the plunger doesn't move much either, maybe a couple millimeters.

    I just went and tested, I unplugged the throttle kicker and coldstarted the car with the AC kompressor kicking on immediately. It started just fine (not engaged on high idle). Of course the car idled very low as it was cold, but having the AC running or not actually affected the idle speed very little, and the car had no problem staying running with no choke/high idle and the AC on withouth the throttle kicker.

    Hot or cold, my car starts wayyyyy better with some throttle input.
    1985 Mercury Grand Marquis LS, "Maisa"
    1995 Chevrolet Caprice Classic STW, "Sally"

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      #17
      My '85 would never start hot without a smidge of throttle.
      1985 LTD Crown Victoria - SOLD
      1988 Town Car Signature - Current Party Barge

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        #18
        Originally posted by DerekTheGreat View Post
        My '85 would never start hot without a smidge of throttle.
        Same with mine. It likes 1/8 throttle or it’s not happy.


        Sent from my iPhone using Tapatalk

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          #19
          the SEFI cars work around this by fully opening the IAC when cranking. CFI you either have to do it manually or rely on the high idle system. The throttle kicker is vacuum operated, so it can't do anything until the engine is already running. Why they didn't use an electric one I don't know, but i think that did actually show up on the late v6 CFI cars. Idle control on these is kind of goofy. You set the speed with the throttle screw, but the only way the ECM can really do anything to change engine speed is to mess with ignition timing, so I guess its worth verifying that the timing is set correctly.
          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

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            #20
            I honestly think it has to do with the TPS- like the injectors aren't firing until that extra bit of voltage. My car wouldn't even cough like a carb'd car would. I did an experiment once when I was pissed at it- I was all like, "Piece of shit.. You're either going to start or you're going to kill the starter in the process." I felt sorry for it after 20 or 30 seconds of just cranking and toe'd in the throttle. It immediately lit off at that point. I don't think I ever checked timing on that rig. Was my first old car aside from the Fury, I was still learning which direction to tighten things and how to round off nuts at that point.

            THat is goofy, and I think V6 CFI stuff had it since '84. Strange that V8's did not.
            1985 LTD Crown Victoria - SOLD
            1988 Town Car Signature - Current Party Barge

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              #21
              Originally posted by DerekTheGreat View Post
              I honestly think it has to do with the TPS- like the injectors aren't firing until that extra bit of voltage. My car wouldn't even cough like a carb'd car would. I did an experiment once when I was pissed at it- I was all like, "Piece of shit.. You're either going to start or you're going to kill the starter in the process." I felt sorry for it after 20 or 30 seconds of just cranking and toe'd in the throttle. It immediately lit off at that point. I don't think I ever checked timing on that rig. Was my first old car aside from the Fury, I was still learning which direction to tighten things and how to round off nuts at that point.

              THat is goofy, and I think V6 CFI stuff had it since '84. Strange that V8's did not.
              Yeah, it feels like I could crank and crank when cold, touching the throttle is like suddenly the engine is getting spark again. Though easier with a bit of throttle, my car does often start with just a turn of the key when hot, or cooled down a bit.
              I like to joke to my friends about the CFI starting procedures and (sometimes) crappy idle. "Just like a fuel-injected engine should be!" Just the best when it fires up and rpm rises quite a bit, I let off the throttle, it immediately wants to die and I stab the throttle again, the engine bogs like all hell and shakes the everliving shit to stay running again.

              One day the CFI will go away... I think I've played it's games long enough.
              1985 Mercury Grand Marquis LS, "Maisa"
              1995 Chevrolet Caprice Classic STW, "Sally"

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                #22
                I remember when I first saw my '88. Opened the hood and saw all the SEFI goodness. All I had to do was twist the key no matter what weather and it just ran. I was in love. Now that I've had it good for so many years, I find myself looking back at CFI fondly. I think what I liked best is the old school look.
                1985 LTD Crown Victoria - SOLD
                1988 Town Car Signature - Current Party Barge

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                  #23
                  a dead spot in the TPS can make it not start, easy enough to check with a voltmeter.
                  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


                    #24
                    I have replaced the TFI connector with a Dorman one from Rockauto. So far no stalling but I only drove two times since the repair. Looks like it was actually the connector that was causing the random stall. It also had sputtered and stalled before the repair when I had slammed the hood shut. That sounded like a bad electric connection to me. So replacing the brittle, corroded connector was the first thing to do. The wires coming from said connector (especially the yellow SPOUT one) were heavily bended in multiple places right at the connector which could very likely have been broken inside the insulating.

                    BUT it is still stalling when coasting and shifting into neutral with AC on. Turn off the AC and it doesn´t kill the engine when shifting into neutral.......I definitely need to check the throttle kicker and vacuum to the device with running engine on/off AC. Maybe that curb idle is set too low or the kicker not working.

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                      #25
                      Originally posted by Hillbillycat View Post
                      BUT it is still stalling when coasting and shifting into neutral with AC on. Turn off the AC and it doesn´t kill the engine when shifting into neutral.......I definitely need to check the throttle kicker and vacuum to the device with running engine on/off AC. Maybe that curb idle is set too low or the kicker not working.
                      Sounds like your idle might be set a little too low. Hot engine and in gear, the idle should be about 600-650 rpm IIRC.
                      Why it stalls when shifting to neutral is completely beyond me...
                      1985 Mercury Grand Marquis LS, "Maisa"
                      1995 Chevrolet Caprice Classic STW, "Sally"

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                        #26
                        Yah when it coasts that throttle plunger thing should be getting vacuum and thus holding the throttle. Mine was like that, anyway. Have you verified correct EGR operation? CFI is pretty particular about that.
                        1985 LTD Crown Victoria - SOLD
                        1988 Town Car Signature - Current Party Barge

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                          #27
                          EGR valve is clean, holds vacuum when applied. PVS switch works as should, too.
                          How to verify proper operation other then that?

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                            #28
                            Originally posted by Hillbillycat View Post
                            How to verify proper operation other then that?
                            If starting and (mostly) running doesn't improve with the EGR valve vacuum line off and plugged, you're fine.
                            If the car runs better and smoother with the EGR off, leave it so and move onto other problems if still present. EGR is nice to have but it can cause a multitude of random issues when not working correctly.
                            1985 Mercury Grand Marquis LS, "Maisa"
                            1995 Chevrolet Caprice Classic STW, "Sally"

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                              #29
                              Makes no difference so I conclude EGR is fine. We´ll see if the stalling was cured by the new connector by time to come. Gotta check curb idle rpms with my meter - probably needs a tad of tweaking up.

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                                #30
                                Only thing I'd do is make sure the vacuum line going to it is routed right- so it opens when commanded to. My car was a F'd up- the EGR wasn't hooked up right, hence the initial ridiculously high idle to compensate.
                                1985 LTD Crown Victoria - SOLD
                                1988 Town Car Signature - Current Party Barge

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