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  • 2.0EFi engine idle speed

    We're still struggling with the engine idle speed. According to the manual a cold engine should start at + - 1300 rpm and at normal temperature reduce to + - 750 rpm. This is what we have : Cold engine starts at at 900 rpm, then goes to about 1200 rpm, then to about 1600 rpm and when warm reduces to about + - 1000 rpm but during traffic driving can go back up to 1600 rpm or down to + - 800 rpm. We've cleaned the throttle body, new idle valve, CO2 is perfect at 2.3%. Mechanic says he's followed tuning procedure by the book. What do you think we're missing ? I've posted this on the M & M OC too. Chris

  • #2
    Have you checked for any air leaks and coolant sensor? I'm also guessing the idle and any adjustments have been made? More info here http://www.maestro.org.uk/forums/showthread.php?t=21427
    Last edited by Jeff Turbo; 9th April 2021, 17:42.
    1958 Ford Consul Convertible. I love this car
    1965 Ford Zodiac Executive. Fab cruiser
    1984 MG Montego EFi in black. Digital dash, nearer completion
    1997 Jaguar Xk8 Convertible. Such a fab car
    2004 MGZT cdti. Great workhorse
    2004 MGZT V8. I love this car

    Comment


    • #3
      Originally posted by Jeff Turbo View Post
      Have you checked for any air leaks and coolant sensor? I'm also guessing the idle and any adjustments have been made? More info here http://www.maestro.org.uk/forums/showthread.php?t=21427
      Thanks for this, this is similar to what is in the factory manual, it's all stuff I can do myself :-) The CO2 is perfect at about 2.3% so I only need to faff about with throttle stop screw & potentiometer, I have the Fastcheck for this :-)
      Thanks
      Chris

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      • #4
        I even have a spare throttle body to practice with :-)

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        • #5
          Originally posted by Soulcharger View Post
          I even have a spare throttle body to practice with :-)
          No worries, Gary was excellent at problem solving
          1958 Ford Consul Convertible. I love this car
          1965 Ford Zodiac Executive. Fab cruiser
          1984 MG Montego EFi in black. Digital dash, nearer completion
          1997 Jaguar Xk8 Convertible. Such a fab car
          2004 MGZT cdti. Great workhorse
          2004 MGZT V8. I love this car

          Comment


          • #6
            Many thanks for that thread link. So I started all over again, CO at 2.4% did the idle valve on-off sequence then used the multi-meter on the potentiometer. According to the thread the reading should be 325mv mine was 008mv there's not much space to get a screwdriver there behind to loosen the screws so I jigged a pair of pliers with a posidrive head and taped the pliers tight............it worked. I got to 325mv very quickly, tightened the screws it changed to 324mv.....close enough finished off the process and I have to say the car drives a whole lot better than before. The throttle hesitation appears to have disappeared. I do own and have used an AR Fast Check unit but you need to keep getting under the dash and back out to car, with the multi-meter it's all done under the bonnet. Will do a double check tomorrow or Sunday, once again many thanks.

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            • #7
              Originally posted by Soulcharger View Post
              Many thanks for that thread link. So I started all over again, CO at 2.4% did the idle valve on-off sequence then used the multi-meter on the potentiometer. According to the thread the reading should be 325mv mine was 008mv there's not much space to get a screwdriver there behind to loosen the screws so I jigged a pair of pliers with a posidrive head and taped the pliers tight............it worked. I got to 325mv very quickly, tightened the screws it changed to 324mv.....close enough finished off the process and I have to say the car drives a whole lot better than before. The throttle hesitation appears to have disappeared. I do own and have used an AR Fast Check unit but you need to keep getting under the dash and back out to car, with the multi-meter it's all done under the bonnet. Will do a double check tomorrow or Sunday, once again many thanks.
              No worries, it's all on the forum somewhere and not the facebook page, glad it's sorted
              1958 Ford Consul Convertible. I love this car
              1965 Ford Zodiac Executive. Fab cruiser
              1984 MG Montego EFi in black. Digital dash, nearer completion
              1997 Jaguar Xk8 Convertible. Such a fab car
              2004 MGZT cdti. Great workhorse
              2004 MGZT V8. I love this car

              Comment


              • #8
                Originally posted by Jeff Turbo View Post

                No worries, it's all on the forum somewhere and not the facebook page, glad it's sorted
                I'll remember that :-)

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                • #9
                  I am also having a few problems setting my cold idle. The car has been set up to read 325mv and idles nicely when hot at 600-700rpm. However, when starting from cold it's very low. Maybe 500rpm or less. I have adjusted the throttle stop screw which raises it a little but don't want it to idle high when up to temp. Car has had a full service and the inlet cleaned out. I have also replaced the temp switch behind the stat and the stepper motor. Can anyone help?

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                  • #10
                    Originally posted by Wild Bill View Post
                    I am also having a few problems setting my cold idle. The car has been set up to read 325mv and idles nicely when hot at 600-700rpm. However, when starting from cold it's very low. Maybe 500rpm or less. I have adjusted the throttle stop screw which raises it a little but don't want it to idle high when up to temp. Car has had a full service and the inlet cleaned out. I have also replaced the temp switch behind the stat and the stepper motor. Can anyone help?
                    Have you tried reseting the idle when cold then seeing what the car does when warm? What year is your car?
                    Last edited by Jeff Turbo; 22nd April 2022, 15:31.
                    1958 Ford Consul Convertible. I love this car
                    1965 Ford Zodiac Executive. Fab cruiser
                    1984 MG Montego EFi in black. Digital dash, nearer completion
                    1997 Jaguar Xk8 Convertible. Such a fab car
                    2004 MGZT cdti. Great workhorse
                    2004 MGZT V8. I love this car

                    Comment


                    • #11
                      Check and clean coolant temperature sender. Had one where the connection was dodgy which made the engine think it was cold when the connection broke and correct when it was OK, so it kept bumping up the idle speed at strange times. It also richened up the mixture for the same reason.

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                      • #12
                        Originally posted by Jeff Turbo View Post

                        Have you tried resetting the idle when cold then seeing what the car does when warm? What year is your car?


                        Hi, do you mean follow the same procedures with idle valve, potentiometer and 30 second reset ? If so no I haven't. I've gone through a process of elimination, I read about the Lucas injection system and the crux of it said 'if one of the parts don't work - then it doesn't work at all'. We've replaced the fuel ECU with a new one, idle valve too, cleaned up throttle body am in the process this weekend of changing the temperature switch, transducer and short speedo cable. Then we know it's not a defect part and could be the wiring, there is a Bosch garage close by who will look at the wiring if it comes to that. I might well give it a go as you suggest when engine is cold see what that does, it's a 11/1986 car. At the moment the temp gauge is showing the temperature at just past the quarter stage whereas before it would show just before the 1/2 way. As you see from the photo (and this was best time, only once when it was this low) it's just under the 1000rpm, "normally" it'll hover around the 1000rpm.
                        Attached Files

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                        • #13
                          Mine is a 1986 Montego EFi

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                          • #14
                            Originally posted by fatjon View Post
                            Check and clean coolant temperature sender. Had one where the connection was dodgy which made the engine think it was cold when the connection broke and correct when it was OK, so it kept bumping up the idle speed at strange times. It also richened up the mixture for the same reason.


                            According to the various documentation I've read this seems to be the weak link in the system, we're changing this over the weekend. Click image for larger version

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                            • #15
                              Originally posted by Wild Bill View Post
                              Mine is a 1986 Montego EFi
                              Do you have these three adjustment screws in your throttle housing. They may have a cap on two and three
                              Attached Files
                              1958 Ford Consul Convertible. I love this car
                              1965 Ford Zodiac Executive. Fab cruiser
                              1984 MG Montego EFi in black. Digital dash, nearer completion
                              1997 Jaguar Xk8 Convertible. Such a fab car
                              2004 MGZT cdti. Great workhorse
                              2004 MGZT V8. I love this car

                              Comment

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