DS23 EFI Running rich
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Thread: DS23 EFI Running rich

  1. #1
    Fellow Frogger! robo's Avatar
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    Default DS23 EFI Running rich

    Hi all, my DS23. EFI is running rich has anyone got any ideas on what can cause this or
    Does anyone know someone that has the diagnostic equipment to tune it?

    Iím in Melbourne.
    Cheers

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  2. #2
    Fellow Frogger! ds21bvh's Avatar
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    Hi Robo,
    Most likely a leaking cold start injector - I would check that first.
    Fuel rail pressure (too high) is another likely cause.
    Kind regards,
    Mark

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    Thanks Mark,

    My cold start injector has been discounted was like that when I got the car
    But the car starts fine when cold.

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    Quote Originally Posted by robo View Post
    Thanks Mark,

    My cold start injector has been discounted was like that when I got the car
    But the car starts fine when cold.
    If it was disconnected then, then its been running rich for some time.
    Cold start injector is a keen to the choke to old conventional carbys.

    JAJEA

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    A cheap piece of diagnostic equipment everyone with a D-jet should have is a 0-3 bar (or thereabouts) pressure gauge. Properly regulated fuel pressure is the single most important aspect of the D-Jet system, since the ECU makes all of its assumptions about how long to open the injectors based on a fuel pressure of 28.5-30.8 psi. The pressure regulator is adjustable, so if the car has run rich for as long as you have owned it, the P.O. may have adjusted the fuel pressure to be too high (possibly to hide another symptom such as lean misfire on acceleration caused by an inoperative throttle position sensor). That may also be the reason the cold start injector is disconnected - no need for it if the engine is always running essentially on "choke"

    You do want to address this issue since long-term running rich will have a very bad effect on the longevity of the engine - bore washing with fuel will cause the cylinders to wear out prematurely.
    JAJEA, dee see and robo like this.
    Cheers,
    John T.

    54 11BL; 61DS19 LHM (son's); 71DS21 BVH; 73SM 3.0; 73SM 2.7EFI; 73SM 3.0 (other son's); 74 Maserati Merak

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    Fellow Frogger! robo's Avatar
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    Quote Originally Posted by citroenthusiast View Post
    A cheap piece of diagnostic equipment everyone with a D-jet should have is a 0-3 bar (or thereabouts) pressure gauge. Properly regulated fuel pressure is the single most important aspect of the D-Jet system, since the ECU makes all of its assumptions about how long to open the injectors based on a fuel pressure of 28.5-30.8 psi. The pressure regulator is adjustable, so if the car has run rich for as long as you have owned it, the P.O. may have adjusted the fuel pressure to be too high (possibly to hide another symptom such as lean misfire on acceleration caused by an inoperative throttle position sensor). That may also be the reason the cold start injector is disconnected - no need for it if the engine is always running essentially on "choke"

    You do want to address this issue since long-term running rich will have a very bad effect on the longevity of the engine - bore washing with fuel will cause the cylinders to wear out prematurely.
    Thanks when I say the cold start injector is disconnected the fuel line has been plugged with a bolt the injector is still plugged in.
    Ive only just got the car on the road this week after 18 months so haven’t done to many miles.
    Where do you connect the gauge to check the pressure?

  7. #7
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    As others have noted, rich running is typically a symptom of the cold start injector leaking. As you have already ruled it out the next thing to check is the fuel pressure as noted above. Best place to hook a gauge on is the line to the coldstart injector.

    Next is the coolant temperature sensor is within spec. Remove the connector from the ECU and measure between pins 11 and 23. At 20deg C you should have a resistance of about 2500 ohm. If its wildly different from this, take the plug off and measure directly at the sensor. It is located in the cylinder head between the distributor and cylinder 1 inlet manifold. If you still get a wildly different reading then replace the sensor. They are readily available from citroen classics or most auto parts stores.

    If the coolant temp sensor checks out then have a very close look at the hoses to the manifold pressure sensor bolted to the firewall next to the heater box. Damaged hoses will cause it to read the wrong pressure and affects the mixture. Also have a look at the electrical connections and clean if necessary. The sensor is adjustable and they do go out of adjustment with time but dismantling / adjusting them is an absolute last resort.

    Next to check is the fuel injectors themselves. If its running the original Bosch ones then chances are they are leaking either from the injector body or the pintle valve. They can be cleaned and flow tested but note that they cannot be repaired easily. The cost of doing so far outweighs the benefits of keeping them. To test, remove the injectors from the inlet runners and place each one in a jar. Cycle the key a few times or jumper the pump relay to pressurise the fuel rail. No fuel should exit the injectors during this test. Even a small amount of dampness is cause for concern as they will leak more under the vacuum of the inlet manifold.
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    Quote Originally Posted by robo View Post
    Thanks when I say the cold start injector is disconnected the fuel line has been plugged with a bolt the injector is still plugged in.
    Plugging a high pressure fuel line with a bolt is a dangerous thing to do, since it is difficult to seal the threads completely, it will drip fuel sooner or later. As others have said, check the fuel pressure at the fuel line leading to the cold start injector. I would add that it is probably a good idea to replace the fuel line.
    robo likes this.
    Cheers,
    John T.

    54 11BL; 61DS19 LHM (son's); 71DS21 BVH; 73SM 3.0; 73SM 2.7EFI; 73SM 3.0 (other son's); 74 Maserati Merak

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    Quote Originally Posted by citroenthusiast View Post
    Plugging a high pressure fuel line with a bolt is a dangerous thing to do, since it is difficult to seal the threads completely, it will drip fuel sooner or later. As others have said, check the fuel pressure at the fuel line leading to the cold start injector. I would add that it is probably a good idea to replace the fuel line.
    I second the motion !!! Old fuel lines that have gone brittle with age and heat do not like being disturbed. There was some reference to fuel lines and fittings on this site a while back. From memory do not use ordinary work drive hose clamps. There are proper fuel injection fittings that are more wrap around in action so less likely to "bunch up" the hose. IIRC these fuel injectors have a barbed push on fitting adding to the initial security but also the drama of removing the now old and tough pipe.
    From personal experience always have more than a quarter of a tank of fuel. The fuel supply pipe in the transverse tank feeds from the right side of the car. The internal pipe is also short and will not be able to use the complete depth of the tank .. combined with our road cambers that are on the wrong side for the fuel supply line means a tank that appears to have plenty .... but the pipe just cannot deliver.
    The fifth injector is timed too in its action .. whether it is actually a function of heat or time I cannot recall. All of the above advice sounds valid to me.
    The additional air control valve is buried down next to the engine sump on the left side near the ( optional ?? ) oil cooler. A difficult device to access but also fitted with a thermo switch. These things are probably not functional any more due to internal corrosion...but the thermo switch hidden somewhere ( several different locations over model runs ) may be giving bad data to the computer .. hence it thinks it is permanently cold and running rich.
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    The thermotime switch is both time and temperature dependant. It's job is to ensure that the cold start injector is deactivated if the coolant temp is over 60deg C I think, can't remember the exact value. The other thing it does is limit its run time to 8 seconds or there about. It does this by removing the ground path for the injector. You will find it on the side of the block under cylinder 3 inlet runner. If it's failed it could cause the cold start injector to run continuously but as your coldstart injector has no fuel supply it should not be causing the problem.

    The temperature switch on the auxiliary air valve is for the dashboard light, it has nothing to do with the EFI system. The only two temperature sensors are the one I mentioned earlier and the one at the air filter. Unplugging the air filter sensor can cause the mixture to richen but nowhere near as dramatically as the coolant temp sensor.

    I think all EFI DS23s got the oil cooler. Seeing as you are in in that part of the engine bay, have a very close look at the oil pressure switch fitted to the cooler. If it looks oily I'd be thinking of changing it. When they fail the sump will be emptied in seconds with very little warning.

  11. #11
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    Quote Originally Posted by faulksy View Post
    The thermotime switch is both time and temperature dependant. It's job is to ensure that the cold start injector is deactivated if the coolant temp is over 60deg C I think, can't remember the exact value. The other thing it does is limit its run time to 8 seconds or there about. It does this by removing the ground path for the injector. You will find it on the side of the block under cylinder 3 inlet runner. If it's failed it could cause the cold start injector to run continuously but as your coldstart injector has no fuel supply it should not be causing the problem.

    The temperature switch on the auxiliary air valve is for the dashboard light, it has nothing to do with the EFI system. The only two temperature sensors are the one I mentioned earlier and the one at the air filter. Unplugging the air filter sensor can cause the mixture to richen but nowhere near as dramatically as the coolant temp sensor.

    I think all EFI DS23s got the oil cooler. Seeing as you are in in that part of the engine bay, have a very close look at the oil pressure switch fitted to the cooler. If it looks oily I'd be thinking of changing it. When they fail the sump will be emptied in seconds with very little warning.
    Thanks Guys, all that info is great and looks like I have a bit of work and investigating to do
    Will start with the fuel pressure,

    Hi Faulksy, I have another cold start injector I purchased from os thought it was NOS but turned up used I’m
    Thinking of reconnecting the one that’s on and see what happens then if it stays on I’ll change over this may tell if its the unit or the switch will it rev at a constant speed Till warms up? The thing is it starts easy without it making me think it’s getting too much fuel all the time.

  12. #12
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    Quote Originally Posted by faulksy View Post
    I think all EFI DS23s got the oil cooler.
    BVH and BVA injections got the oil cooler - BVM cars did not.
    Cheers,
    Mark

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    It's easy enough to check with a meter. When the engine is up to running temp there should be no voltage on the wires connected to the cold start. If there is then there is either a problem with the thermotime switch or the wiring to the coldstart injector.

    Assuming your auxiliary air valve is functioning, the engine should rev to 1000rpm or so when first started and progressively drop down to 800rpm or there about as the engine warms up. It depends if you have a manual or auto gearbox as to exactly how far the idle will drop. Is it running rich at idle or all speeds?

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    Fellow Frogger! robo's Avatar
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    Quote Originally Posted by faulksy View Post
    It's easy enough to check with a meter. When the engine is up to running temp there should be no voltage on the wires connected to the cold start. If there is then there is either a problem with the thermotime switch or the wiring to the coldstart injector.

    Assuming your auxiliary air valve is functioning, the engine should rev to 1000rpm or so when first started and progressively drop down to 800rpm or there about as the engine warms up. It depends if you have a manual or auto gearbox as to exactly how far the idle will drop. Is it running rich at idle or all speeds?
    It is definitely running rich at start up see pic but I’m not sure when warm can’t see any smoke when driving.
    I would like someone with a D to drive mine too see how it feels to them the last D I had was over 20 years ago
    And it had a carby.

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    IMG_1558231508.847390.jpg


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    Quote Originally Posted by robo View Post
    IMG_1558231508.847390.jpg


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    That alone is no real indicator of whether it is running rich. So many variables. How long has it been idling ? When did it last get decently hot enough to dry out the whole exhaust system ?
    A D with its transverse muffler and two long pipes will readily drip water from the exhaust.... water condensation alone is no indicator either.
    Better off using your nose. Does it smell rich ?
    What is its consumption like on the road ? My DS 23 automatic was never able to better 24 mpg, the DS 21 4 speed manual could regularly better 30 mpg .. both figures for open road cruising. The 23 automatic was quite a guzzler in traffic, but it was driving an air con too, in Brisbane heat and humidity.

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    I get this on starting mine up. Seems to be getting better with more regular driving and long runs.


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    [QUOTE=Secretsenor;1615373]I get this on starting mine up. Seems to be getting better with more regular driving and long runs.


    Yes mine is the same when warm its not blowing any black smoke i can put my hand under the exhaust and nothing but i need to put cardboard under it or my my drive is going to have a nice black spot. I haven’t given it a long drive yet as only just on the road
    And ironing out other issues like getting a bit hot when stopped the thermo fan is not working.

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