DS23 EFI not revving
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Thread: DS23 EFI not revving

  1. #1
    BVH Roger Wilkinson's Avatar
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    Default DS23 EFI not revving

    Hello folks,

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    I started my DS23 EFI today for the first time in a couple of years. I put a good battery in it and it took a lot of cranking but eventually started and idled fine. But it would not rev. Step on the throttle: nothing. Pull on the throttle butterfly: nothing. Any ideas?

    Thanks,
    Roger

  2. #2
    1000+ Posts gerrypro's Avatar
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    Corrosion on the throttle angle sensor tracks?
    This unit that is on the throttle butterfly shaft can be dismantled. Some circuit board cleaner will remove the corrosion from the tracks and clean the contact points of the wipers. It is really just like one bog old fashioned rheostat.
    Cheers Gerry

  3. #3
    1000+ Posts Ken W's Avatar
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    There is a throttle stop switch that brings in the idle circuit and a ladder contact on the throttle butterfly that adds extra injection pulses on throttle advance to simulate a accelerator pump. Maybe the throttle stop switch is staying closed and not opening when the butterfly is opened.

    Cheers, Ken

  4. #4
    Fellow Frogger! citroenthusiast's Avatar
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    Can you be more specific about the symptom? If you open the throttle butterfly does the engine quit running or does it continue to idle? Any popping or sputtering?

    The MAP sensor should compensate for the throttle clicker malfunction (albeit there would be hesitation that would affect driveability). Remember, engine speed is determined by how much air you can get air into the cylinders. If you are getting enough air into the cylinders to rev, then either the engine will speed up (combustible mixture) or it will quit running (non-combustible mixture).

    If the car continues to idle properly with the throttle butterfly wide open, then I would look for an obstruction in the intake system that is preventing air from getting into the cylinders. Did a mouse get in and build a nest inside the intake?
    Last edited by citroenthusiast; 6th July 2018 at 01:31 AM.
    JohnW likes this.
    Cheers,
    John T.

    54 TAV Legere; 61DS19 LHM BVH (son's); 71DS21 BVH; 73SM 3.0; 73SM EFI (Megasquirt); 73SM 3.0 (other son's)

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    Or a hornet/mud wasp?

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    Also check exhaust for obstruction.

  7. #7
    BVH Roger Wilkinson's Avatar
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    Quote Originally Posted by citroenthusiast View Post
    Can you be more specific about the symptom? If you open the throttle butterfly does the engine quit running or does it continue to idle? Any popping or sputtering?
    It ran at a steady idle no matter whether I opened the throttle butterfly with the accelerator pedal or directly with my hand. I could feel air being sucked into the air intake but did not investigate further. I could drive it slowly and carefully on a concrete floor by feathering the clutch pedal but it was developing very little power.

    Thanks for the tips; keep them coming. Meanwhile, I will keep investigating.

    Roger

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    I had the same problem with mine and solved it with a new fuel filter. Have you checked what pressure the rail is at with the engine running? IT should be 28-30 PSI or roughly 2Bar.

    The throttle position sensor is really badly named, it doesn't actually tell the ECU how open the throttle is. All it does is send out of phase injection pulses to the injector drivers.

    Are all the cylinders firing? might be worth cleaning the trigger points in the base of the distributor.

  9. #9
    Real cars have hydraulics DoubleChevron's Avatar
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    Hi Roger,

    check the wiring. Upto the manifold pressure sensor (and plumbing). I'm pretty sure Djet throttle spindle doesn't have any switches or idle indicators. All it does is send a square wave when the throttle is opened (ie: it tells the injection calcuator to temporarily richen the fuel ... like the accelerator pump on a carby).

    Did I mention the wiring You have had a battery in and out right ?? Check the wiring ... it all there being moved around on the battery frame. The bosch wiring harness are shit qaulity. I'm leaning towards fuel pressure given it won't rev. Does it lean out and die as you open the throttle The fact it idles tells me the cacluator is working, the injectors are working, the injectors have a good earth, the fuel pump is working .... the temp senders have signal etc.

    Forgive the dumb suggestion ........................... There is petrol in the tank right

    seeya,
    shane L.
    'Cit' homepage:
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    Yay ... No Slugomatics


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  10. #10
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    Hello Roger,

    I got to know my fuel injection system far too well a few years ago. So here are my pennies worth...just some idle jottings really

    1 If your throttle valve is truly opening (have you checked that there is not something physically broken or something blocking it as others suggest?), and there is no response then I wonder why the engine does not stutter and stall (too lean).

    2 Still on throttle body. To make things a bit easier, disconnect the duct from throttle body to air-cleaner. Now you can see if it is actually opening and you can hear if the "suck" changes as you open it. You can further check the the throttle body by turning ignition on (dont start engine) and then turning the throttle body with your hand. You should hear about 20 clicks from the injectors

    3 Assuming nothing is broken on the throttle body, then it next suggests to me to check the MAP sensor, the larger sensor on the firewall Perhaps the vacuum line to it is blocked or has a leak (good idea to check that). Disconnect the vacuum line that runs from the throttle body to the MAP sensor. Leave it attached to MAP sensor and suck on it. No repsonse suggests something amiss with MAP sensor

    4 Still on MAP sensor. You can follow the instructions in various publications to do some other basic checks on this sensor. Better to substitute a MAP sensor that you know works to see if that is problem. I can send you the publications if you send me an email address. They are easy to follow. A first would be wiring (there are 4 leads to MAP sensor). Are they all sound (mine were not). And if you can, trace/check the wiring back to ECU

    5 Could it be a problem with fuel. Yes. Two years ago I installed a pressure gauge (they are cheap) in the fuel line that runs to cold start injector. Now I could see what was going on with fuel delivery. . And it revealed all sorts of strange things like fuel pressure being spot on until you opened throttle at which point it fell to zero. Eventually I cleaned out tank, replaced filter near pump and even replaced pump. I don't think replacing pump was really necessary. And still there was air in the line and funny pressure readings until, by itself, it started to work properly (i.e. maintain a constant and set pressure of about 2.2 bars)

    6 Could the ECU be faulty.. Yep. But check all the other things first. They don't cost much money

    Whewww

    Cheers
    ian
    Dave Rogers likes this.
    Blueduck (aka Ian Downie)
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