Announcement

Collapse
No announcement yet.

EEC III CFI rough idle on cold start

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    EEC III CFI rough idle on cold start

    Anyone here intimately familiar with EEC III CFI? The Mark VI has been idling really rough on a cold start for awhile now. I've been ignoring it because 1. I don't drive it that often 2. You give it the tiniest bit of throttle and it goes away until you let off the pedal, one good 1/4 to 1/2 throttle rev and it goes away until the next cold start. It idles just fine when the engine is started warm, the only thing I've tried it adjusting the idle up and down slightly with the adjustment on the throttle kicker solenoid, that doesn't seem to make a difference. It doesn't do it when the weather it cold because the choke takes over. Should I have it set so the electronic choke still engages in hot weather?
    2002 Mercury Grand Marquis LSE, Sylvania Zevo LED Headlights, MSD Blaster Coils, K&N Cold Air Intake, Dual Exhaust, 3.27's - Dally Driver

    1983 Lincoln Continental Mark VI, Smog Delete - Summer Cruiser


    ​

    #2
    Yeah, since these don't actually compensate the A/F ratio when cold, the choke pull-off mechanism should still engage when started cold. Doesn't it have a high speed position and then a lower speed position as it warms up? If so, try and adjust it so it sets to the lower idle speed. EDIT: It may be sweaty hot out there to you, but the engine is still very much cold at those ambient temps.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

    Comment


      #3
      Its just a high idle mechanism, might need to engage even in warmer weather. Should be able to loosen it and rotate to adjust how long it takes to drop out.
      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


        #4
        I currently have it set to not engage in this warm of weather. I’ll mess with it and find where it engages and see how it goes.
        2002 Mercury Grand Marquis LSE, Sylvania Zevo LED Headlights, MSD Blaster Coils, K&N Cold Air Intake, Dual Exhaust, 3.27's - Dally Driver

        1983 Lincoln Continental Mark VI, Smog Delete - Summer Cruiser


        ​

        Comment


          #5
          Depending on your results, it might be better off that way.
          1985 LTD Crown Victoria - SOLD
          1988 Town Car Signature - Current Party Barge

          Comment


            #6
            I moved it to where it just grabs the first notch on the choke. It's definitely better now, it wasn't a huge deal anyway just a minor annoyance.
            2002 Mercury Grand Marquis LSE, Sylvania Zevo LED Headlights, MSD Blaster Coils, K&N Cold Air Intake, Dual Exhaust, 3.27's - Dally Driver

            1983 Lincoln Continental Mark VI, Smog Delete - Summer Cruiser


            ​

            Comment


              #7
              With my EEC-IV CFI cars, which mechanically work the same way and just have a smarter brain behind the operation, they want the high idle mechanism to operate even in hot weather.

              The 85 is straight up broken; 5 to 10 seconds of a tiny bit of throttle pedal helps it behave better when allowed to come back to idle. The 84 seems to work fully correctly, and it'll rev pretty high at whatever setting it drops on even in hot weather (haven't looked at it/don't remember, but I think it's the second-lowest setting). Tapping the pedal will then drop it by another setting, and then the final drop comes after a couple minutes of running (which ISTR is done by the computer via vacuum to force it to drop even if the choke thermostat hasn't gotten there yet).

              There is no choke. The CFI unit just happens to use choke-style idle controls and uses a choke thermostat as a form of mechanical timer.

              I don't think it's accurate to say the computer is unable to compensate for cold starts by adding fuel. Adding fuel (and playing with timing) is actually all it can do. The problem is it needs more air, and since this system does not have an IAC or electronic throttle stepper, the ways it is able to obtain more air are kind of archaic.

              Current driver: Ranger
              Panthers: 83 GM 2dr | 84 TC | 85 CS
              | 88 TC | 91 GM
              Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
              Gone: 97 CV | 83 TC | 04 Focus | 86 GM
              | Junkyards

              Comment


                #8
                Yes, no choke, but if I remember right it's still labeled "Choke pull-off mechanism" or something like that.

                I do think it's accurate to say that about the computer, as that was my conclusion with my '85. Adding more fuel when cold is all it would need to do when cold, not more air. That's what a choke does in carb'd car; fuel flow stays the same but it reduces the air flow coming into the carb, thus richening the mixture. Something about being cold and the fuel condensing on the intake runners and dropping out of suspension within the air, science, science stuff I don't fully understand ect. You can get around that by increasing the velocity at which the air/fuel mix flows through those intake runners, which is exactly what Ford chose to do with V8 CFI. You can prove this by taking one of your carbureted cars, disabling the choke such that it's wide open and then starting it cold. Hold the throttle such that once it lights off, it's approximately winging at about 2000 rpm. It'll run just fine. More RPM in addition to more fuel seems nice, as that promotes more oil flow and probably reduces the chance of valvetrain noise.
                Last edited by DerekTheGreat; 07-21-2022, 06:58 AM.
                1985 LTD Crown Victoria - SOLD
                1988 Town Car Signature - Current Party Barge

                Comment


                  #9
                  You're correct that more fuel is needed for a cold start, for reasons related to those you listed. However, CFI is already able to add that fuel. It is not able to raise the idle speed by adding air. So the high idle linkage is serving the purpose of adding air, and the computer is going to give it [correct amount of fuel for the amount of open throttle]+[an additional amount of fuel based on the cold temperature].

                  Nothing about how the CFI throttle body works allows a mechanical or manual "enriching" function; all that "choke-ish" linkage is doing is adding air (and providing ability for the computer to cancel adding that air re: the pull-off). The computer does the rest.
                  Last edited by kishy; 07-21-2022, 09:55 AM.

                  Current driver: Ranger
                  Panthers: 83 GM 2dr | 84 TC | 85 CS
                  | 88 TC | 91 GM
                  Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
                  Gone: 97 CV | 83 TC | 04 Focus | 86 GM
                  | Junkyards

                  Comment


                    #10
                    I'd love to measure the exhaust mixture or look at fuel tables, but my experience and tinkering told me my '85 did not richen the mixture for cold starts or cold drivability. If it did, I'd suspect it would be able to sustain a much lower idle speed despite still being cold. For example, my 1989 K1500 has similar fuel injection set up, only it has an IAC and can enrichen for cold starts. When I start it even in the winter, it starts around 1300 RPM and comes right down to 1000 until it warms up to the point of closed loop operation. I've even unplugged the IAC, still runs when cold. SEFI stuff will run cold too, could be the difference between port fuel injection and traditional induction though. However, my '85 CFI would not idle lower than 1500 RPM when cold, so I compromised and adjusted the pull off linkage crap such that it idled around 1800, I believe the sticker on the fan shroud wanted it to go around 2,200 rpm, just absurd. If I tried to lower the idle while cold, I could hear it start to drop off due to running lean. The only thing I don't have to support this is the hard data of the actual fuel mixture. However, I feel I did a damn fine job tuning the carb on my '69 Plymouth. While I tinkered with that, same type of systems. At one point I had both cars at the same time and that's what helped speed me along to my conclusion about the lack of CFI to provide cold start enrichment.

                    However, I'd be convinced otherwise if someone showed me factory fuel tables from an EEC-IV and EEC-III V8 CFI ECM for both cold and hot running conditions. That or maybe you could even hook a wideband O2 sensor to your car and show me what it does cold vs warm at the same idle conditions. Or try this, start your '84 cold. Pop the air cleaner lid and use your hand as a rudimentary choke. See if you can take the idle down without it stalling. I don't know why I never tried that with my '85.
                    Last edited by DerekTheGreat; 07-21-2022, 12:14 PM.
                    1985 LTD Crown Victoria - SOLD
                    1988 Town Car Signature - Current Party Barge

                    Comment


                      #11
                      The fuel mix is very much influenced by the air and coolant temp sensors. If those are bad though, it won't get the fuel mix right and there is no way for it to correct until the coolant sensor reaches whatever point is required for it to start looking at the oxygen sensors.
                      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


                        #12
                        I'm sure with CFI they do anything but help enrichen the fuel for cold starts/drivability.

                        Although I am going to run an experiment with my truck. Going to let it get up to temp, unplug the IAC and then try and start it & drive it the next morning. If it behaves like my CFI car did, then there's fuel for the fire which suggests CFI does enrichen the fuel mixture for cold starting/drivability. However, with the way my CFI car behaved, it wouldn't even idle in park at less than 1500 RPM when cold before sputtering and dying. My truck already idles at 1000 RPM when cold with zero issues. Riddle me that..
                        1985 LTD Crown Victoria - SOLD
                        1988 Town Car Signature - Current Party Barge

                        Comment


                          #13
                          My CFI was rich on cold starts, tbh it was rich everywhere
                          Seriously though my CFI ran alright when cold, just had to keep it from stalling with some throttle.
                          1985 Mercury Grand Marquis LS, "Maisa"
                          1995 Chevrolet Caprice Classic STW, "Sally"

                          Comment


                            #14
                            The longer this thread persists, the more I am glad I've never had a CFI experience.

                            *queue rust free CFI wagon at a reasonable price near me*
                            1990 Country Squire - weekend cruiser, next project
                            1988 Crown Vic LTD Wagon - waiting in the wings

                            GMN Box Panther History
                            Box Panther Horsepower and Torque Ratings
                            Box Panther Production Numbers

                            Comment


                              #15
                              Oh I'd snatch another EEC-IV CFI car in a flash if I had the cash haha. I'm just genuinely curious and now not so convinced of my previous position. Science will commence! My car ran great once it was where Ford wanted it, just had to fight the brakes with how eager the car was to move when cold. Once it was off the choke-pull-off gizmo & warm, it was great, loved driving it and it was pretty miserly on fuel. Would bark the tires from a stop. Miss that car, may it rest in peace.

                              Maybe there was something wrong with my car. Kishy, what's the lowest RPM your '84 will maintain when started cold?
                              Last edited by DerekTheGreat; 07-22-2022, 10:20 AM.
                              1985 LTD Crown Victoria - SOLD
                              1988 Town Car Signature - Current Party Barge

                              Comment

                              Working...
                              X